EP2193362A2 - Capteur de charge en suie - Google Patents

Capteur de charge en suie

Info

Publication number
EP2193362A2
EP2193362A2 EP08804980A EP08804980A EP2193362A2 EP 2193362 A2 EP2193362 A2 EP 2193362A2 EP 08804980 A EP08804980 A EP 08804980A EP 08804980 A EP08804980 A EP 08804980A EP 2193362 A2 EP2193362 A2 EP 2193362A2
Authority
EP
European Patent Office
Prior art keywords
temperature
sensor device
hot wire
measuring
particles
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Withdrawn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
EP08804980A
Other languages
German (de)
English (en)
Inventor
Gerald Hauser
Günther HAUSER
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.)
Hauser Andreas
Original Assignee
Hauser Andreas
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 Hauser Andreas filed Critical Hauser Andreas
Priority to EP10160088A priority Critical patent/EP2500719A1/fr
Publication of EP2193362A2 publication Critical patent/EP2193362A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/06—Investigating concentration of particle suspensions
    • G01N15/0656—Investigating concentration of particle suspensions using electric, e.g. electrostatic methods or magnetic methods

Definitions

  • the invention relates to a sensor device for determining electrically conductive and / or electrically charged particles contained in a gas stream, in particular soot particles in the exhaust gas stream of a diesel engine, comprising at least two electrodes to be arranged in the gas stream.
  • Another aspect of the invention relates to a sensor device for determining a mass flow of a medium comprising a heatable temperature sensor, preferably a hot wire, which is arranged so that it can be placed in the mass flow, a control or control unit, which is formed, the heatable temperature sensor preferably to heat the hot wire in a first measurement phase to a certain temperature above the temperature of the mass flow and to determine the mass flow, preferably by measuring a voltage which is required to maintain this particular temperature of the hot wire.
  • a heatable temperature sensor preferably a hot wire, which is arranged so that it can be placed in the mass flow
  • a control or control unit which is formed
  • the heatable temperature sensor preferably to heat the hot wire in a first measurement phase to a certain temperature above the temperature of the mass flow and to determine the mass flow, preferably by measuring a voltage which is required to maintain this particular temperature of the hot wire.
  • Soot charge sensors are known in various structural configurations.
  • a method for measuring particles contained in a gas stream usually provides in the prior art that the particles between see two electrodes deposit. From a certain amount of deposited particles, resistance bridges between the electrodes cause a resistance change. This change in resistance between the electrodes is measured.
  • DE 195 36 705 A1 shows a method and a device for the quantitative determination of soot particles in an exhaust gas stream with a measuring capacitor of a shell and an inner electrode. Between the electrodes, an electric field is established, which, when it is flowed through by a gas stream with electrically conductive or charged particles, is influenced. The voltage between the two electrodes is kept constant by a suitable control device, so that a charging current must flow between the electrodes and the voltage source. About this charging current is closed to the amount of particles contained in the gas stream.
  • DE 198 17 402 C1 shows a sensor arrangement which functions according to a similar principle and which provides heating of the sensor in order to thermally destroy particle deposits.
  • DE 10 2004 039 647 A1 shows a soot charge sensor with a measurement capacitor through which an exhaust gas flow flows, in which the measurement signal is processed by a charge amplifier with DC coupling. Furthermore, this soot charge sensor provides a third electrode, which charges the particles as a corona electrode.
  • DE 10 2005 016 395 A1 shows a soot sensor which determines the particle charge via a measuring resistor which is not insulated on its surface.
  • the particles deposited on the surface of the measuring resistor cause a resistance change according to the deposition amount.
  • DE 10 2004 043 121 A1 shows a sensor element for gas sensors for determining the concentration of particles in gas mixtures, which has at least one first and one second measuring electrode to which a voltage is applied.
  • the first measuring electrode is at least partially covered by a porous material which is permeable to the particles to be determined.
  • DE 103 19 664 A1 discloses a sensor for detecting particles in a gas stream, comprising two measuring electrodes arranged on a substrate made of an insulating material However, the measurement accuracy of these sensors is not sufficient for a number of applications and thus to be further improved
  • DE 27 18 474 C3 and DE 31 03 051 A1 show thermal or electro-cal flow meters with a PTC thermistor-powered probe and with a device for measuring and compensating the fluid temperature.
  • a quotient is formed from a The signal proportional to the current in the PTC thermistor and a signal which is proportional to the difference between the fluid temperature and a fixed temperature above the reference temperature of the PTC thermistor probe
  • two values are supplied to the inputs of a divider.
  • Another disadvantage of known solutions is high wear, inter alia, due to corrosion, in particular of the electrodes, and impairment of the resistance measurement by ash constituents, which permanently deposit on the sensor surfaces during particle combustion.
  • the existing solutions have the disadvantage that they measure the amount of particles.
  • an externally determined gas velocity is included.
  • this object is achieved by a sensor device for determining electrically conductive and / or electrically charged particles of the type mentioned above, in which at least one of the electrodes is completely embedded in a non-conductive material in the region to be arranged in the gas flow.
  • the non-conductive material may be, for example, a non-conductive potting compound, such as glass.
  • a complete embedding can be achieved by coating the at least one electrode or immediately surrounding it on all sides by the non-conductive material.
  • the complete embedding can be designed so that the at least one electrode is electrically insulated from its surroundings.
  • the at least one electrode can also be embedded in a casting process in a hardening, non-conductive material.
  • the embedding can be designed such that the electrode does not come into contact with deposits or is exposed to other wear-inducing influences, so that the life of the at least one electrode is extended and quality losses due to wear and corrosion and ash deposition are prevented or mitigated ,
  • the at least one electrode can be designed, for example, as a comb electrode, bifilar winding, electrode grid or bridge resistor. Furthermore, the electrode can be arranged on a support, for example of ceramic, which is embedded together with the at least one electrode in the non-conductive material. An optionally provided heater may be embedded together with the at least one electrode in the non-conductive material.
  • the sensor device comprises a measuring unit which is electrically coupled to the at least two electrodes and which forms the particles completely in a non-conductive state by measuring the change of a capacitive resistance by depositing particles on the at least one.
  • conductive material embedded electrode by means of alternating current, in particular higher-frequency alternating current to determine.
  • alternating current in particular higher-frequency alternating current
  • the frequency of the higher-frequency alternating current is preferably at least 200 kHz and can be increased up to approximately 30 MHz in order to further increase the measuring sensitivity.
  • this higher frequency is required because the capacitance changes are very small and can occur, for example, depending on the electrode area, in the order of 5 to 50 pF.
  • a certain capacitive resistance of the measuring arrangement can be determined. If soot particles deposit on the insulated surface of the at least one electrode, they form an electrically conductive coating which generates an additional capacitance in interaction with the electrodes located below the insulating layer. By measuring this change in capacitance, the amount of particles can be determined. The measurement of the amount of soot particles is therefore based on the measurement of the capacitive resistance. A measurement based on the ohmic resistance is eliminated by the complete isolation of the electrodes according to the invention.
  • a further aspect of the invention relates to a sensor device for determining electrically conductive and / or electrically charged particles of the type mentioned above, which is characterized in that at least one of the electrodes is coil-shaped and the measuring unit is formed, the particles over to determine a measurement of the change in an inductive resistance by flowing the at least one electrode of the particle-containing gas stream.
  • the at least one electrode may be formed as a cylindrical, cantilevered induction coil, in which the particles contained in the gas stream preferably flow through the coil axially and influence the inductance due to their permeable properties.
  • the coil may, for example, have a circular or quadratic cross-sectional shape. The axial flow through the coil is preferred because the inductive resistance changes very little when the particles flow past the outside of the coil, because then only the stray field of the coil is affected.
  • the coil is integrated in a high-frequency oscillating circuit with a certain resonant frequency. As soot particles pass through the coil shaped electrode, the inductance is detuned and a different resonant frequency occurs depending on the amount of soot.
  • the measurement of the amount of soot in g / h can be determined for example by means of a frequency count.
  • the coil may be superficially conductive or - for example, for corrosion protection - be embedded in a non-conductive material.
  • a conductive surface of the coil has a metrological effect only if the windings of the coil are so close to each other that can form soot bridges by deposition of particles. With sufficient spacing of the coil turns from each other, preferably a distance of about 2 mm or more, no metrologically relevant deposition occurs because particles are blown away by the exhaust gas flow.
  • the at least one electrode completely embedded in a nonconductive material has the form of a coil and the measuring unit is configured to completely divide the particles by depositing particles on the at least one non-conductive material by measuring the change in an inductive resistance to determine embedded electrode.
  • the electrode is designed in the form of a coil, which is integrated in a high-frequency resonant circuit with a specific resonant frequency. As soot particles deposit on the isolated surface of the electrode, the inductance is detuned and a lower resonant frequency occurs depending on the soot build-up. The measurement of soot deposition in g / h can be determined, for example, by means of a frequency count.
  • the invention can be further developed in that the measuring unit is designed to measure the change in the capacitive or inductive resistance via an interconnection in at least one measuring bridge, in particular a Wheatstone half or full bridge.
  • the resistance measured in the state without particle deposition can be compensated in a bridge circuit by an external, adjustable resistor. If soot particles deposit on the insulated surface of the sensor or flow through the coil-shaped electrode, they change the capacitance or inductance, which leads to an immediate detuning of the measuring bridge.
  • the invention can be further developed by a heating control unit, which is electrically or thermally coupled to the at least two electrodes and designed to at least partially eliminate the deposition of particles by heating the sensor device, in particular to a thermally destructive temperature.
  • the heating to a thermally destructive temperature of the particles is preferably carried out by a constant temperature control of the heater, since the exhaust gas stream usually has lower temperatures and cools the heater.
  • the burning temperature of preferably at least 650 ° C can be maintained. Depending on the gas temperature and gas speed, this may require, for example, a heat output of up to 150 watts.
  • the sensor device comprises a heating control unit, the sensor device can be cleaned automatically, without an external access to the sensor device is needed, which would require, for example, the removal of a sensor.
  • the electrode When forming the electrode as a cylindrical coil through which the gas stream flows, burn-out by burning is possible, but not necessarily required, since the particles are transported away from the gas flow with sufficient spacing of the coil windings and no deposition relevant to measurement forms on the coil.
  • the heating control unit is designed to initiate the heating upon reaching a predetermined value of the deposition quantity, the operating time or the measured particles.
  • the limit may be the amount of accumulated particle deposits.
  • the heating can be initiated even after a certain duration or operating time of the sensor.
  • the particles measured over the transit time can be used to determine a limit value and its achievement, for example via the integration of the measured particles over the runtime.
  • This limit is preferably determined by calibration. For example, with a constant soot emission, the course of the capacitive resistance is observed over time. First, the change of resistance is almost linear. With stronger deposition, the resistance change less and the slope of the curve is flatter. Preferably, the end of the linear range is set as a limit.
  • the invention can be developed by virtue of the fact that at least one of the electrodes electrically or thermally coupled to the heating control unit is designed to heat the sensor device and / or the sensor device comprises a resistance heater which is electrically coupled to the heating control unit and in particular meander-shaped resistance heater. to heat the sensor device.
  • the heating control unit cooperates with at least one of the electrodes, so that the electrode serves as a heating element for the sensor device.
  • the electrode consists of resistance material with a temperature-dependent resistance coefficient in order to be used as an electrical heater and to realize a temperature-related control.
  • the resistance heater it is advantageous to couple a separate resistance heater with the heating control unit.
  • it is advantageous to form the resistance heater meandering since a meandering arrangement of the resistance heating has no inductance, which could see the measurement result of the inductive resistance vertig-, but has only a capacity which is not hindering for the measurement ,
  • the invention can be developed by the fact that the sensor device is designed to determine the particles via a measurement of the change in an ohmic resistance by deposition of particles on at least one not completely embedded in a non-conductive material electrode.
  • This training combines the measurement of particles via the change of a capacitive and / or inductive resistance with the measurement of the Change of ohmic resistance.
  • the combination of different measurement techniques can contribute to increasing the measurement accuracy and reducing the probability of failure of a sensor device.
  • particles can deposit on at least one non-insulated part of at least one electrode.
  • the sensor device mentioned at the outset is characterized in that at least one of the electrodes is formed at least partially as a grating, in particular as a surface grating.
  • the measurement sensitivity can be increased significantly by the replacement of a measuring electrode, for example made of sheet metal, by an electrode grid and the setting time or the time constant can be significantly reduced.
  • the grid can be significantly increased field strength.
  • the measurement signal can be considerably amplified by this arrangement.
  • the measurement quality and measurement accuracy of the sensor can be significantly improved.
  • the grid is formed from at least one wire, in particular at least one tungsten wire.
  • the surface grid according to the invention may, for example, be a point-welded grid of thin tungsten wire, for example with a diameter of 50 ⁇ m.
  • the grid is formed as a fabric or braid.
  • a plurality of individual wires or a continuous wire can be arranged so that a plurality of wires or wire sections, which are aligned in different directions, are located within a certain surface section.
  • the grid is aligned in the longitudinal or transverse direction to the flow direction of the gas flow.
  • the sensor device for determining a mass flow of a medium of the aforementioned type is characterized by a measuring device for determining the temperature of the medium in a second measuring phase, preferably via a measurement of the resistance of a hot wire, in particular of the hot wire, a control unit.
  • the invention provides a temperature-controlled mass flow sensor.
  • a hot wire is heated by a quiescent current to a higher temperature than that of the mass flow. This higher temperature is kept constant. Depending on the gas velocity, heat is removed from the wire. Since the temperature of the hot wire is kept constant, the current through the wire increases. This current is calibrated, for example, in kg Ga masse / h and thus serves as a measure of the mass flow.
  • the control unit for heating the hot wire in a first measurement phase to a certain temperature above the temperature of the mass flow and for determining the mass flow by measuring a voltage, the is required to maintain this particular hot wire temperature may be identical to the control unit for controlling the hot wire in the first measurement phase to a temperature that is dependent on the temperature of the medium determined in the second measurement phase.
  • Decisive for the measurement of the mass flow is the constant temperature difference between medium and hot wire temperature.
  • the invention provides for determining the temperature of the medium in a second measuring phase, preferably via a measurement of the resistance of a hot wire, in particular of the hot wire, in the first measuring phase for determination the mass flow is used.
  • the measuring device for determining the temperature of the medium in the second measuring phase can be designed as any temperature sensor suitable for the field of application and is not limited to the determination of the temperature via a measurement of the resistance of a hot wire.
  • the correction unit can be designed to correct the mass flow determined from the voltage measured in the first measuring phase by a value dependent on the temperature determined in the second measuring phase.
  • a control unit controls the temperature to which the hot wire is to be heated in the first measurement phase.
  • the heating of the hot wire in the first measurement phase for determining the mass flow is carried out at a temperature dependent on the temperature of the gas flow measured in the second measurement phase.
  • the invention makes it possible to apply the principle of hot wire-based mass flow measurement in a wide temperature range by heating the hot wire to a temperature which is controlled as a function of the respective mass flow temperature, and in which the result corresponds to one of the respective gas flow temperature Value is corrected.
  • the invention offers the advantage of determining the mass flow required for indicating a particle concentration. This advantage is also evident in particular in combination with the mass flow sensor with a particle sensor, since in this combination no measured values have to be interrogated via other, external sources.
  • the invention offers the further advantage of being able to react very quickly to temperature changes and thus further improving the quality of the measurement result.
  • the measurement according to the invention of the mass flow at strongly fluctuating temperatures of the medium advantageously also permits a map-related exhaust gas recirculation required for the control of NO x emission, as provided for in the exhaust gas standard EURO VI.
  • the present invention provides the instantaneous mass flow and the temperature of the exhaust gas, from which the return rate required for the map-related exhaust gas recirculation can be determined.
  • the invention can preferably be developed in that the control unit is designed to perform the first measurement phase and the second measurement phase alternately.
  • the hot wire is heated to a certain temperature above the temperature of the mass flow alternately first in the first measurement phase and determines the mass flow via a measurement of the voltage required to maintain this particular temperature of the hot wire.
  • the temperature of the medium is determined, which is passed on to a control unit.
  • the control unit controls the heating of the hot wire to a certain temperature above the temperature of the medium determined in the preceding second measurement phase.
  • the temperature of the mass flow actually obtained in the second measuring phase is used in the first measuring phase in each case.
  • the output of the determined mass flow in the first measurement phase is corrected by a value that depends on the temperature of the mass flow determined in the second measurement phase.
  • the sensor device can be developed in that the sensor device comprises a heatable temperature sensor, in particular a first hot wire, for the first measurement phase and a temperature sensor, in particular a second hot wire, for the second measurement phase and the control unit is designed, the first measurement phase and the second Perform measuring phase continuously in parallel.
  • a heatable temperature sensor in particular a first hot wire
  • a temperature sensor in particular a second hot wire
  • the control unit is designed, the first measurement phase and the second Perform measuring phase continuously in parallel.
  • a separate sensor for the first measurement phase, a heatable temperature sensor, preferably a first hot wire, and for the second measurement phase any, suitable for the application temperature sensor, preferably a second hot wire
  • a separate sensor for the first measurement phase, a heatable temperature sensor, preferably a first hot wire, and for the second measurement phase any, suitable for the application temperature sensor, preferably a second hot wire
  • the invention may preferably be characterized be trained that the hot wire for determining the temperature is driven with a constant current. Furthermore, it can be achieved that the measuring sensitivity remains essentially the same over the entire temperature range.
  • the first and the second hot wire are controlled differently. While the first hot wire for the first measurement phase for determining the mass flow is controlled to a constant, above the temperature of the mass flow temperature and the voltage required to maintain this particular temperature of the hot wire is determined, the control is carried out in the second hot wire for the second Measuring phase for determining the temperature of the medium with a constant current according to the principle of a resistance thermometer.
  • the hot wire for determining the temperature with such a small constant current, in particular a current of 5-10 mA, is controlled such that the temperature of the hot wire is below the temperature of the mass flow.
  • the control takes place at the temperature heating wire with a very low, constant current, which produces as little as possible or only a very small heating effect. This is necessary in order that the change in the temperature of the hot wire depends as far as possible on the temperature of the medium surrounding the hot wire.
  • the current applied to drive the temperature heating wire is about 5-10 mA, while, for example, the quiescent current of the mass flow heating wire, depending on the medium temperature, can vary between 600 and 1600 mA.
  • the invention is preferably developed by the sensor device comprising means designed to control the temperature of the heatable temperature sensor, preferably of the hot wire, to determine the mass flow to a predetermined, in particular constant, difference from the temperature of the medium.
  • Decisive for the measurement of the mass flow is a constant temperature difference between medium and hot wire temperature.
  • the temperature of the hot wire is controlled so that it rises or falls with the temperature of the medium, so that the temperature difference between the hot wire and the medium always remains the same. If this temperature difference, for example, 100 0 C, this remains constant, even if the gas temperature z B from 400 0 C to 800 0 C increases.
  • the hot-wire temperature is thus controlled to a temperature of 500 0 C (at a gas temperature of 400 ° C) or 900 ° C (at a gas temperature of 800 0 C).
  • the temperature-controlled quiescent current of the hot wire is kept constant by a control circuit at each medium temperature, so that the heat dissipation by the mass flow, depending on the medium velocity, is the same at each temperature level.
  • the invention can be further developed by virtue of the fact that at least one hot wire consists of a material with the resistance temperature coefficient as constant as possible
  • Hot wires are preferably made of platinum. It is essential that the metallic material has a resistance temperature coefficient which is as constant as possible. If this is not the case, as for example in the case of tungsten, a linear linearization of the non-linear behavior must be performed and integrated into the sensor device.
  • the invention can be further developed in that at least one hot wire consists of a material with the highest possible mechanical strength.
  • a high mechanical strength increases the longevity of the sensor design. Since the hot wire typically has a very small diameter and at the same time, for example, must withstand the exhaust gas pulsations in the exhaust pipe of a diesel engine, the mechanical strength is of great importance for preventing hot wire failure, for example by tearing or breaking. This is of particular importance when the sensor device is used, for example, in the exhaust system of vehicles, where an expansion or a repair of the sensor device would be associated with a high outlay. For example, tungsten has a very high mechanical strength, but also a disadvantageous nonlinear resistance temperature behavior.
  • the sensor device comprises means which are designed to heat up at least one hot wire, at least for a short time, to a temperature at which particles deposited on the hot wire are thermally destroyed.
  • a hot wire has a temperature lower than the combustion temperature of the particles, particles can deposit on the hot wire. This deposit degrades the heat transfer from the medium to the wire. It is therefore advantageous to heat the wire prior to a measurement by brief increase in current to a particle thermally destructive temperature, so that any deposits burn to clean the hot wire.
  • a circuit for controlling a sensor device for determining a mass flow of a medium wherein a first circuit arrangement comprises a variable resistor and at the temperature measuring point of the temperature change of the variable resistance corresponding voltage change is applied, via a line branch to a second circuit arrangement and a third circuit arrangement is guided; the second circuit arrangement comprises a further variable resistor which is controlled to a temperature dependent on the voltage change resulting from the supply line from the first circuit arrangement, and the third circuit arrangement comprises a measuring resistor and the voltage or voltage change applied to the measuring resistor is amplified, around the change in temperature of the variable chen resistance corresponding voltage change is corrected from the first circuit arrangement and output at a measuring point.
  • This circuit can be preferably developed by a first circuit arrangement comprises a variable resistor which is grounded and connected via the resistors to a positive voltage source and an operational amplifier, which picks up the voltage between the variable resistor and the resistor with its non-inverting input and with its inverting input connected to the resistor, and the operational amplifier at the temperature measuring point outputs a voltage change corresponding to the temperature change of the variable resistor, which is conducted via a line branch to a second circuit arrangement and the inverting input of an operational amplifier in a third circuit arrangement;
  • the second circuit arrangement comprises a further variable resistor which is connected to a positive voltage source via a resistor and a controlled switching element (pnp transistor) and is controlled via an operational amplifier and a resistor to the temperature obtained from the feeder branch of the first circuit arrangement the resistor between the feeder branch from the positive voltage source via the controlled switching element to the resistor and the connection between a measuring resistor in the third circuit arrangement is grounded, and the third circuit arrangement a measuring resistor which is grounded and connected to the variable
  • FIG. 1 shows a schematic cross section of an embodiment of a second aspect of the present invention
  • FIG. 2 shows a schematic plan view of a further embodiment of a second aspect of the present invention
  • FIG. 3 shows a schematic plan view of a further embodiment of a second aspect of the present invention
  • FIG. 4 is a schematic plan view of a further embodiment of a second aspect of the present invention.
  • FIG. 5 is a schematic view of a first embodiment of a first aspect of the present invention
  • FIG. 6 shows a schematic functional diagram of an embodiment of a third aspect of the present invention
  • Figure 7 a circuit of a third aspect of the present invention.
  • FIG. 1 shows a schematic cross section of an embodiment of a second aspect of the present invention with comb electrodes 301 which are mounted on a ceramic carrier 304. Below the ceramic carrier 304, an electric heater 305 is arranged. Comb electrodes 301, ceramic carriers 304 and heater 305 are molded into a nonconductive potting compound 302, e.g. Glass, embedded and completely electrically isolated.
  • a nonconductive potting compound 302 e.g. Glass
  • particles 303 deposit during operation of the sensor. These form an electrically conductive coating on the surface 306 of the non-conductive potting compound 302 and thus influence the capacitance of the comb electrodes 301.
  • the assembly 300 By heating the assembly 300 by the heater 305 to a thermally destructive temperature the particles 303, the assembly 300 is "burned", ie the assembly 300 is heated by the heater 305 until at least on the surface 306 of the non-conductive Potting compound 302 sets a temperature at which burn the deposited on the surface 306 of the non-conductive potting compound 302 particles 303. This temperature is maintained until the surface 306 of the non-conductive potting compound 302 deposited particles 303 are substantially burned and essentially no deposited particles 303 are more on the surface 306 of the non-conductive potting compound 302.
  • FIG. 2 shows a schematic plan view of one embodiment of the second aspect of the present invention according to FIG. 2.
  • the comb electrodes 401 which are arranged on a ceramic carrier 402, can be seen.
  • the arranged below the ceramic support 402 electric heater is not shown in this plan view.
  • Comb electrodes 401, ceramic carrier 402 and the Heater are embedded in a non-conductive potting compound 402, eg, glass, and completely electrically insulated
  • FIG. 3 shows a schematic plan view of a further embodiment of a further aspect of the present invention. It can be seen that the electrode 501 has a meandering shape and is arranged on a ceramic carrier 502. The electrode 501 may be formed as a high-resistance thin-film resistor.
  • FIG. 4 shows a schematic plan view of a further embodiment of a second aspect of the present invention.
  • the electrode 601 is arranged in the form of an induction coil on a ceramic carrier 603.
  • the electrode 601 and the ceramic carrier 603 and a meandering heater (not shown) optionally arranged on the underside of the ceramic carrier are embedded in a nonconductive potting compound 602 and completely electrically insulated.
  • the coil-shaped arrangement of the electrode 601 is incorporated in a resonant circuit (not shown) as an inductance.
  • a resonant circuit (not shown)
  • the inductance of the electrode 601 is detuned.
  • the assembly 600 can be cleaned as described analogously in Figure 1 of particle deposits.
  • FIG. 5 shows a schematic view of an embodiment of a first aspect of the present invention with an electrode holder 201 and an electrode 202 designed as a surface grid.
  • the surface grid is composed of several composed of individual wires 203, which are spot-welded at several points 204
  • This grid shape of the electrode allows a much higher field strength, which leads to a significant increase in the measurement sensitivity and an amplification of the measurement signal and at the same time reduces the response time or time constant.
  • FIG. 6 is a schematic functional diagram of an embodiment of a third aspect of the present invention.
  • a first hot wire 1 serves as a mass flow sensor and is regulated to a constant temperature in a first measurement phase.
  • a second hot wire 3 serves as a temperature sensor and is regulated to a constant current in a second measurement phase.
  • the temperature of the medium flowing through the sensor device is measured in the second measuring phase 5.
  • the mass flow is determined by the current required to maintain the constant temperature. 7.
  • First and second measuring phases run continuously and in parallel.
  • the temperature 5 measured in the second measuring phase via the temperature heating wire 3 is forwarded to the control 2 6. Since the regulation to constant temperature 2 thus depends on the current medium temperature, the determined mass flow 7 must also be corrected by a corresponding temperature correction value 8 so that the correct mass flow is output at the output mass flow 9. At the output temperature 19, the current medium temperature is output.
  • FIG. 7 shows a circuit of a third aspect of the present invention.
  • a first circuit arrangement 97 comprises a variable resistor 102 which is grounded and has a positive resistance across resistors 113-115 Voltage source 113 is connected.
  • An operational amplifier 104 picks up the voltage between the variable resistor 102 and the resistor 114 with its non-inverting input and is connected to the resistor 15 at its inverting input.
  • the operational amplifier 104 outputs at the temperature measuring point 110 a voltage change corresponding to the temperature change of the variable resistor 102, which is conducted via a line branch to a second circuit arrangement 98 and the inverting input of an operational amplifier 107 in a third circuit arrangement 99.
  • the second circuit arrangement 98 comprises a further variable resistor 103 which is connected via a resistor 111 and a controlled switching element 1 10 (pnp transistor) to a positive voltage source 109, and via an operational amplifier 105 and a resistor 112 to that of the feeder branch of the first circuit arrangement 97 temperature is controlled.
  • the resistor 112 is connected between the feeder branch from the positive voltage source 109 via the controlled switching element 1 10 to the resistor 11 1 and the connection between a measuring resistor 101 in the third circuit arrangement 99 to ground.
  • the third circuit arrangement 99 comprises a measuring resistor 101, which is grounded and connected to the variable resistor 103 of the second circuit arrangement.
  • a first operational amplifier 106 picks up the voltage between the measuring resistor 101 and the variable resistor 103 at its non-inverting input and represents a zero point 16 at its inverting input of the operational amplifier 106.
  • a second operational amplifier 107 corrects the amplified voltage applied to the non-inverting input of the measuring resistor 101 by the voltage change of the temperature measurement 110 applied to the inverting input, so that a temperature-corrected mass flow is output at a measuring point 108.

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  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)

Abstract

L'invention concerne un dispositif capteur destiné à déterminer une quantité de particules électroconductrices et/ou chargées d'électricité contenues dans un flux gazeux, en particulier une quantité de particules de suie dans le flux de gaz d'échappement d'un moteur diesel, lequel dispositif comprend au moins deux électrodes à placer dans le flux gazeux, au moins une des électrodes étant entièrement enrobée d'un matériau non conducteur dans la zone à aménager dans le flux gazeux. Un autre aspect de l'invention concerne un dispositif capteur destiné à déterminer un débit massique d'un fluide, comprenant un fil chaud conçu de façon à pouvoir être placé dans le flux massique, une unité de commande et de régulation conçue pour chauffer le fil chaud à une température déterminée supérieure à la température du flux massique, au cours d'une première phase de mesure, et déterminer le débit massique par la mesure d'une tension nécessaire au maintien de la température définie du fil chaud. L'invention est caractérisée par un dispositif de mesure destiné à déterminer la température du fluide, au cours d'une seconde phase de mesure, par une mesure de la résistance d'un fil chaud, en particulier du fil chaud, une unité de commande, conçue pour commander l'échauffement du fil chaud, au cours de la première phase de mesure, à une température qui dépend de la température du fluide déterminée au cours de la seconde phase de mesure, et une unité de correction conçue pour corriger le débit massique, déterminé à partir de la tension mesurée au cours de la première phase de mesure, d'une valeur variable avec la température, déterminée à partir de la résistance du fil chaud mesurée au cours de la seconde phase de mesure.
EP08804980A 2007-10-01 2008-10-01 Capteur de charge en suie Withdrawn EP2193362A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP10160088A EP2500719A1 (fr) 2007-10-01 2008-10-01 Capteur de charge de suie

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DE202007013735 2007-10-01
PCT/EP2008/063191 WO2009047195A2 (fr) 2007-10-01 2008-10-01 Capteur de charge en suie

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EP10160088A Division EP2500719A1 (fr) 2007-10-01 2008-10-01 Capteur de charge de suie
EP10160088.0 Division-Into 2010-04-15

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EP2193362A2 true EP2193362A2 (fr) 2010-06-09

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EP10160088A Withdrawn EP2500719A1 (fr) 2007-10-01 2008-10-01 Capteur de charge de suie

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WO (1) WO2009047195A2 (fr)

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DE102010042914B4 (de) * 2010-10-26 2012-05-24 Wachtel GmbH & Co. Bäckereimaschinen-Backöfen Messvorrichtung und Verfahren zur Erfassung von Verbrennungsluftbestandteilen

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DE3103051C2 (de) 1981-01-30 1985-08-01 Paul Walter Prof. Dr. Baier Vorrichtung zur Messung des Durchflusses eines strömenden Fluids
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WO2009047195A2 (fr) 2009-04-16
WO2009047195A3 (fr) 2009-06-18
EP2500719A1 (fr) 2012-09-19

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