DE102008009494A1 - Device for measuring concentration and/or size distribution of soot particles in diesel exhaust gas of diesel vehicle in workshops, has magnets exhibiting magnetic field to deflect particles to electrodes dependent on size - Google Patents

Abstract

The device has deflecting systems comprising an arrangement producing a magnetic field (14) from a permanent magnet and/or electromagnets. The magnets exhibit the magnetic field to deflect electrically charged particles (18, 19) to electrodes (20)dependent on size strongly different from a normal flight path. The electrically charged particles impinging the electrodes deliver respective charges to the electrodes. The electrically charged particles are deflected to the electrodes downstream to a flow direction of an exhaust gas stream (3).

Description

The The invention relates to a device for detecting the concentration and / or the size distribution of electrically charged Particles in gas streams, in particular of soot particles in diesel exhaust gases according to the preamble of the claim 1.

at Combustion processes and especially in the combustion of diesel fuel in diesel engines, the inevitable generation of Combustion particles such as soot particles in the Environmental discussion, since such particles harmful to health Can have effect. It therefore creates a high pressure to reduce such emissions, resulting in the creation of environmental zones to reduce particulate matter in cities as well as a retrofit obligation of existing vehicles and precipitation of equipment of new vehicles with particulate filters can. But also in the review of stoves or the like. Fireplaces, for example, with wood or pellets run as fuel, it turned out that In this case, high particulate emissions occur, which are the general Fine dust pollution come and this increase again significantly.

There at the same time the use of renewable raw materials and the Use of diesel vehicles for other reasons advantages and therefore be funded in principle should come, the capture and reduction of the resulting Fine particulate pollution is a high priority. It is therefore Various measuring methods have been developed, in particular the resulting soot particles in emissions from diesel engines recorded and thus controlled variables for a Reduction of emissions of the combustion process can be obtained can. Also, extensive research is on the concentration and the particle size distribution been hired in diesel exhaust.

The Most of the soot particles contained in diesel exhaust gases are in a size range between 0.05 and 1.0 microns Particle diameter, the so-called accumulation mode, with smaller Particles in the size range between 0.005 and 0.05 microns depending on the combustion parameters in the so-called nucleation mode and, depending on the sulfur content of the diesel fuel, can be contained in the exhaust even in high proportions. Become coarse particles with diameters greater than 1.0 μm also discharged, which are typically Rußwandablagerungen acts, which form in the exhaust system and through the exhaust stream can be solved and carried away. For measurement Such particle numbers and distributions are different measuring methods known.

The most commonly used method for the determination of Particle concentration is the so-called gravimetry, whereby the particles containing gas stream passed through a suitable filter material will be weighed and the particles accumulating in it. This elaborate, but in itself quite well controllable method has however, some influencing factors that cause that it is only suitable for laboratory use, with about the particle emissions of at Diesel engines can be determined. So are highly accurate measuring equipment to be calibrated, such as a particle scale, The filter materials may react with the to be filtered exhaust gas or the particles therein and the To be measured gas flow must be very finely controlled to a corresponding to obtain representative measurement. Therefore, this is suitable highly accurate and calibratable measuring methods not for the Field use.

Therefore have been a number of alternative measuring methods in recent years, partly also developed for field use, the briefly mentioned below.

The The most accurate determination of the amount of particles is achieved by combustion the particle on a filter in the oxygen flow, while the case resulting carbon dioxide are measured by IR spectroscopy can.

A Another method is to use the inert mass the particle. In the TEOM (Tapered Element Oscillation) and in the QCM (Quartz Crystal Microbalance) will be the detuning one with the Particle current impinged quartz oscillator measured by the additional particle mass is generated.

A Another possibility is to greatly increase the gas flow accelerate and so the low inertial forces reinforce the single particle. So-called. Niederdruckimpaktoren work on this principle. In general, those with the particle flow weighed impactor stages, whereby the particle mass size distribution can be determined cumulatively over the duration of the measurement. The weighing The impactor stages rely on the low particulate emissions, the z. B. occur in Euro4 vehicles, but longer Measuring times ahead. This disadvantage can be seen in ELPI (Electrical Low Pressure Impactor) can be avoided by removing the particles electrically charged before entering the impactor and the on the Impactor stage incoming current measured with an electrometer becomes. This allows the determination of the aerodynamic particle number size distribution at low temporal resolution.

One Another approach assumes the soot particles optically prove that they are the light in the visible wavelength range absorb almost completely. There are a number of Opacimeters and Extinktionsmeßgeräten to the Soot particle measurement can be used. A disadvantage of this However, the process is that the sensitivity of light absorption depends on the diameter of the particles. Therefore, about Particles artificially enlarged below a limit diameter, to optically detect these enlarged particles to be able to. This is the principle of the condensation nucleus counter (CNC / CPC), which with very good time resolution Gesamtpartikelanzahlen measure up.

Around Information about the size distribution too win, exists next to the impactor so-called SMPS (= scanning Mobility Particle Sizer), in front of the condensation nucleus counter an electric classifier (DMA = Differential Mobility Analyzer) is switched. The particles are electrically charged and then scherungsfrei as sheath flow to a clean air flow where. This gas stream is passed through an electric field, in which the particles according to their charge and size to get distracted. If a defined voltage is applied, you can only particles of a certain size class Leave DMA. This section of the particle size spectrum is then quantified in the condensation nucleus counter. A Variant consists in the already charged particles with a To measure electrometer. In contrast to the impactor is with this Measuring principle determines the electrodynamic number size distribution. Another system combines classifier and detector in one device. The DMA is divided in sections, with the individual Sections electrically isolated against each other and with an electrometer are connected. For each section, then a size class corresponds, the impinging electric current is measured, which is proportional to the particle number.

A Another way to measure particles is to use different ones rapid diffusion of the particles due to Brownian molecular motion exploit. In doing so, smaller particles diffuse faster than size. In the so-called diffusion batteries are networks or Apertures connected in series. In each stage of the diffusion battery the smaller particles are retained most proportionally, because they collide by diffusion with the net or the aperture and thus be withdrawn from the sample gas. From the particle decrease of From one step to the next, the size distribution can then be determined determine. The particles are i. d. R. again with condensation nucleus counters demonstrated.

Besides exist surface-based measuring methods in which the particle surface is loaded. The charges will be measured and thus deliver the measuring signal. Are available Devices in which the loading of the particles by diffusion of gas ions (DC) or by light (PAS) happens.

The currently used particle number measurement technology with devices, such as B. SMPS and ELPI, is only for the production of qualitative Statements on particle number and size distribution suitable, however, from the possibility of quantitative, so absolute measurement of these properties, far from it. About that In addition, one has to realize that the measured particle number is strong depends on the test conditions.

It shows up that for measuring the mass of particles only the gravimetry can be calibrated directly. Other methods are Can be calibrated indirectly via gravimetry or coulometry. A calibration to measure the number of particles is currently not possible. Furthermore, there are doubts regarding the reproducibility, which is crucial for registration measurements is. Here is the most for most devices Proof of sufficient compliance with the requirements respectively.

From the EP 1 540 308 B1 a device is known for measuring the concentration of charged particles present in a flowing gas, in which a first measuring electrode for measuring the particle charge is present. An ionizer charges the particles before passing through the measuring electrode, whereby the charged particles are deflected by a deflection electrode in such a way that they partially deposit on the measuring electrode and release their charge there, which can then be measured via operational amplifiers. By providing a plurality of measuring electrodes, a size distribution of the depositing particles can also be determined. A disadvantage of this device, however, is that in addition to the depositing on the measuring electrodes and the measuring electrodes in the gas flow only passing particles exert a significant influence on the measured values at the measuring electrodes, as between the only passing electrically charged particles and the charges on the measuring electrodes to interactions occurs and it comes to the measurement result falsifying charge shifts. Also, the velocity of the particles to be detected in the device according to the EP 1 540 308 B1 different, whereby also the measurement result deteriorating side effects for the actual measurement occur.

task The present invention is therefore a generic Device further develop such that a more accurate and more stable measurement of particle concentration and particle size distribution becomes possible.

The Solution of the problem of the invention arises from the characterizing features of claim 1 in Interaction with the characteristics of Oberbe handle. Further advantageous Embodiments of the invention will become apparent from the dependent claims.

The The invention is based on a device for detecting the concentration and / or the size distribution of electrically charged Particles in gas streams, in particular of soot particles in diesel exhaust, comprising a device for electrical charging the particle and one downstream of the device arranged for electrical charging deflection, with the the particles to at least one in the flow direction of the Gas flow downstream measuring device are deflected out. Such a generic device is further developed by the fact that the deflecting a magnetic field generating arrangement of a permanent magnet and / or a Electromagnets whose magnetic effect depends on the particles different in size from their respective size from their normal trajectory and to the at least one measuring device deflects, wherein the incident on the measuring device particles deliver their respective load to the measuring device. By using a magnetic field for deflecting the particles from their normal Trajectory through the device and the combination of a permanent magnet with constant and an electromagnet with variable adjustable magnetic effect can be achieved, on the one hand the deflection of the electrically preloaded particles almost completely takes place and therefore the deposition of these particles on the measuring device also with a high degree of efficiency. on the other hand is avoided by being misappropriated Particles which in the device of the prior art at the Although measuring device fly past, but nevertheless the measurement influence by a charge shift, no longer occur can and thereby the measurement with the inventive Device is much more accurate and accurate. Also is due the magnetic field effect the separation of the particles according to their size significantly improved, resulting in a classification of the particles easier and more reliable according to their respective sizes becomes. This will both the detection of the number of particles as well at the same time recording the size distribution the particle in the exhaust stream is improved and simplified. Also a substantially maintenance-free operation is possible, because the device without susceptible wearing parts gets along. It goes without saying that the inventive Device not only on the use for Rußerfassung limited to diesel engines, but always there where fine dust occur during combustion processes, if necessary with appropriate modification can be used.

In In a first advantageous embodiment, the magnetic field generating arrangement of a permanent magnet and / or a Electromagnets divert the particles in a plane along the the measuring device or the measuring devices one behind the other in Flow direction of the gas stream are arranged. By the advantageous linear and parallel alignment The measuring devices can thus be of small area possible embodiment of the measuring device or more Measuring devices achieved a high accuracy of the measurement method become.

Especially It is advantageous if the magnetic field for the deflection the particle is formed such that small particles, preferably in the range between 1 to 5 nm, stronger and larger Particles, preferably in the range between 5 to 10 nm, weaker to get distracted. Dependent on such a distraction from the particle size it is possible the various particles in the sub-stream to be detected due to their inertia targeted to distract so that they hit the downstream measuring device (s) and there deliver their charge so that the charge change can be detected well by measurement. The magnetic field effect ensures advantageous in combination with a focusing of the partial flow the particle about an upstream aperture then that the trajectory of the particles in the measuring device accurately set and adjust. This will be almost all particles are deflected towards the measuring device and caught there. In a particularly advantageous embodiment, in this case, the magnetic field the particles perpendicular to the flow direction of the gas stream distracted. In this case, the charge delivered to the measuring device the particles impinging on the measuring device are a measure of the concentration of the particles in the gas stream.

In a first advantageous embodiment, only one measuring device can be arranged in the flow direction of the gas behind the deflecting device. Such a low-cost and simply constructed device, the z. B. can be designed as a simple retrofit solution to existing diesel engines, it can be operated so that the deflection deflects the particles with a variable magnetic field effect from their trajectory. Such a variable magnetic field effect ensures that in each case only a subset of the penetrating particles is deflected with a defined particle size exactly to the measuring device depending on the currently acting magnetic field and incident on the measuring device. Particles of other particle sizes are deflected too strong or not strong enough and miss the one measuring device. These are not him summarizes. If one changes the strength of the magnetic field effect but now preferably periodically, so z. B. periodically sliding or periodically in some regions clocking a predetermined magnetic field strength range, then each other part of the different sized particles is deflected to the measuring device out and can be measured there. If the respectively detected particle size is then combined depending on the particular magnetic field strength and the resulting deflection of the particles, then a statement has been made about the number of particles of a particular size or a specific size range deposited on the one measuring device. With sufficiently fast tuning of the magnetic field strength range, in addition to the likewise determinable particle concentration, a timely statement about the size distribution of the particles can be obtained, which can then be used for example for controlling the combustion behavior of the particle generator, such as a diesel engine.

In In another embodiment, it is conceivable that more than one measuring device arranged one behind the other in the flow direction of the gas becomes. Such, metrologically more complex, but parallel and therefore more timely measuring device measures it each time a defined range of size distribution the particle to be detected and therefore can work more accurately. In this case, the deflection device is advantageous, the particles in a to deflect substantially constant magnetic field effect, so due to their persistence at the same time particles of all occurring Particle sizes affect different subrange the measuring device or a number of consecutively arranged depositing individual measuring devices. Now the number and the spatial arrangement of the staggered measuring devices chosen appropriately, so can have a larger Measuring range a precise division into collectives about the same size Particles take place. Such a device can be used as a workshop system used for adjusting diesel engines, the device only temporarily connected to the exhaust system of the diesel engine becomes. It is also conceivable to use such a device on a wanderer about for diesel engines of high-priced vehicles permanently to attach to their exhaust system.

Especially it is advantageous here that the resulting magnetic field from a superposition of a constant permanent magnetic Magnetic field and an adjustable electromagnetic magnetic field can generate. The permanent magnetic magnetic field can be chosen so that it alone sufficient Deflection of the largest particles produced in such a way that these particles are on the farthest from the upstream aperture distant measuring device one with several measuring devices Deposited equipped device. The distraction of smaller particles then requires the additional application of the magnetic field effect of the adjustable electromagnetic magnetic field making it stronger be distracted and located on the closer to the aperture Deposit measuring devices. When using only one measuring device The electromagnetic field can be between a maximum value and a minimum value are periodically controlled and the above described different deflection in each case different Effect particle sizes.

Especially favorable for achieving a high and consistent Magnetic field strength is when the cross-section of the device for the passage of the gas stream in the field of magnetic field effect rectangular is designed to be a high magnetic field strength in one to produce a relatively small air gap.

In Further embodiment, it is conceivable that the measuring devices Have heating devices with which the impinging particles periodically burned again and the measuring devices thereby cleaned can be. By heating the measuring device can the otherwise permanently depositing particles, in the long run would affect the effect of the measuring equipment, so be heated far, that these burn and thereby the surface the measuring equipment is cleaned. By a vote of this Heating processes with the periodic tuning of the magnetic field strength can be a stand alone measuring device before the measurement in each range of particle size before from each pre-deposited particles of a different size range be cleaned.

From It is also advantageous if the device for electrical Charging the particles has an ionization device. A Such ionization device can be charged, for example, from the same Are formed surfaces between which pass through the particles and in which they then advantageous simple electron charges They then later return to the measuring equipment submit.

It is conceivable in this case that at least one aperture is arranged in front of and / or behind the ionization device, which passes only a focused gas flow and in particular a limited to a constant flow rate of particles gas stream. Such a focus ensures that only a defined number of particles have to be processed by the measuring devices or the measuring device in the area of the measuring devices and thereby ensures definable and defined measuring conditions. In this case, in another embodiment, the aperture in front of the ionization device have a supercritical nozzle.

From It is particularly advantageous that the device in the bypass to the actual gas flow can be arranged and then only a partial flow of the Gas flow through the device flows. This will avoided that the measuring devices the entire particle flow z. B. have to process the exhaust system of a diesel engine and thereby the particle flows on metrologically meaningful Partial flows can be limited. Advantageous it is still, if this device via a Isokinetic removal device to the main flow of the gas stream is connected. As a result, it is ensured that the removal device a subset of the gas stream takes in the equally distributed all Particle sizes and particle distributions as in the original gas stream are present. This is the Partial flow passing through the device, representative for the main exhaust stream and therefore can for regulatory purposes be used in the generation of the main exhaust gas stream.

Farther an evaluation device can be functional with the measuring devices be connected, preferably based on amplifier circuits the number and / or distribution of the impinging particles or their Charges registered on the various measuring devices and evaluates. Such evaluation can about it In addition, the operation of the device, so about the Mag netfeldstärke and other possibly useful sensors or query to the various setting parameters of the device optimally to combine with each other.

Conceivable it is also that the evaluated signal of the number of particles and / or the size distribution of the particles as Controlled variable in the generation of the particles, in particular as a control variable in the exhaust gas control of a diesel engine or as a control value for a current particulate filter is used, already favorable to the emergence of the particles to influence or recognize when the effect of a particulate filter is not given properly.

From Another advantage is that the device is approximately at a factory Calibration, but also with possibly necessary controls can be calibrated gravimetrically.

A particularly preferred embodiment of the invention Device shows the drawing.

It demonstrate:

1 A schematic representation of the various functional assemblies of the device according to the invention with a plurality of measuring devices arranged one behind the other and their spatial arrangement relative to one another in a side view,

2 - An enlarged portion of the device according to 1 in the region of the generation of the magnetic field in the deflection device.

At the exhaust pipe 1 z. B. a diesel vehicle not shown is with flanges 2 fastened the device according to the invention, wherein from the exhaust gas flow 3 the diesel engine is a partial flow 4 via an isokinetic sampling 5 taken and over a byway 6 (Bypass) is passed. One as a supercritical nozzle 7 Adjustable aperture provides as a flow controller for a constant flow of exhaust gases containing all kinds of particles that originally come from the cylinders of the diesel engine and in the exhaust stream 3 are included. The nozzle 7 is adapted so that the signals can be optimally processed in the device and z. B. no overloading with particles 18 . 19 occurs.

The partial flow 4 the exhaust gases including the soot particles 18 . 19 go through an ionization path 8th that z. B. from the grounded pipe 6 and one on high voltage 9 lying central wire electrode 11 consists. The high voltage 9 is going through an implementation 10 the wire 11 fed. In the ionization section 8th become the particles 18 . 19 charged and usually with a simple electron charge.

The charged particles 18 . 19 pass through a beam-limiting aperture 13 in a magnetic field 14 a, which consists of a current-carrying coil 15 is formed, supported by a strong permanent magnet 16 and perpendicular to the plane of the drawing 1 directed into (arrow end 12 ). About the stream 17 through the coil 15 can the resulting magnetic field 14 be set to a certain value, leaving small particles 18 (eg 1-5 nm) strong and larger particles 19 (eg, 5-10 nm) weaker by the Lorentz force from its normal trajectory in the sub-stream 4 be deflected. In the 2 This area of the device is again shown in an enlarged plan view, with the narrow design of the tube 25 to ensure an equally strong magnetic field 14 over the whole width of the pipe 25 is guaranteed.

After the deflection of the particles 18 . 19 through the magnetic field 14 catch individual electrodes 20 the particles 18 . 19 on, a current flows into the respective electrode 20 by suitable amplifier 21 is amplified and an evaluation unit 22 is supplied. In this case, the electrodes 20 be operated with an electrical bias. The Si gnal 23 the evaluation unit 22 can then z. B. the engine management of the diesel engine z. B. be fed back as a controlled variable or as a measured value.

With a suitable arrangement of the electrodes 20 In terms of dimensions and number, all relevant data on the number of particles can be found 18 . 19 all mass areas are won simultaneously. In a not further illustrated embodiment of the device is instead of in 1 represented a total of four electrodes 20 only a single electrode 20 provided on which the particles 18 . 19 distracted by a time-varying magnetic field 14 hit and be measured. By changing the strength of the magnetic field 14 Other areas of the different particle sizes can always be deflected appropriately and thus time-staggered a measurement of all occurring particle sizes with only one electrode 20 will be realized.

The cross section of the pipe 25 in the area of the magnetic field 14 should preferably be designed rectangular in order to realize the highest possible magnetic field strength in a relatively small "air gap" can.

To the eventual heavy occupancy of the electrodes 20 with particles 18 . 19 can eliminate the electrodes 20 each with a heater 24 be provided that the accumulated soot particles 18 . 19 burns.

In this way, in particular, an online measurement of the emission of soot particles 18 . 19 of diesel engines, while data for mass-dependent soot particle distribution are obtained from which the intended function z. B. a soot particle filter of the vehicle can be detected.

• 1) einfacher Aufbau, die Vorrichtung kann mit zwei Flanschen 2 in jedes Abgassystem 1 aller Fahrzeuge eingebaut werden,
• 2) weitgehende Wartungsfreiheit,
• 3) vollständige Information über Partikelanzahl bei verschiedenen Partikelmassen,
• 4) die Vorrichtung kann als kostengünstige Version mit wenigen Messelektroden in alle Fahrzeuge eingebaut werden, aber auch als hochgenaues Messgerät mit entsprechend vielen Messelektroden und Kanälen zum Einsatz z. B. in Werkstätten konzipiert werden,
• 5) die Vorrichtung kann auch mit nur einer Elektrode betrieben werden, und die Daten über die Anzahl der Partikel 18, 19 mit unterschiedlichen Massen über eine Variation des von der Spule 15 erzeugten Magnetfeldes 14 erreicht werden,
• 6) Kalibrierbarkeit der Vorrichtung mittels Gravimetrie.

The device has the following advantages:

• 1) Simple construction, the device can with two flanges 2 in every exhaust system 1 all vehicles are installed,
• 2) extensive freedom from maintenance,
• 3) complete information about the number of particles at different particle masses,
• 4) the device can be installed as a low-cost version with few measuring electrodes in all vehicles, but also as a highly accurate measuring device with a corresponding number of measuring electrodes and channels for use z. B. be designed in workshops,
• 5) The device can also be operated with only one electrode, and the data on the number of particles 18 . 19 with different masses over a variation of the coil 15 generated magnetic field 14 be achieved
• 6) Calibratability of the device by means of gravimetry.

1

exhaust pipe

2

flange

3

Exhaust stream / flow direction

4

of removed Partial flow from exhaust gas flow

5

removal device

6

bypass

7

Aperture / supercritical jet

8th

ionization probe

9

supply high voltage

10

execution

11

wire electrode

12

magnetic field direction resulting magnetic field

13

beam- cover

14

resulting magnetic field

15

current-carrying Kitchen sink

16

permanent magnet

17

power current-carrying coil

18

small particle

19

size particle

20

measuring electrodes

21

amplifier

22

evaluation

23

unevaluated signal

24

heater

25

pipe

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1540308 B1 [0016, 0016]

Claims (37)

Device for detecting the concentration and / or the size distribution of electrically charged particles ( 18 . 19 ) in gas streams, in particular of soot particles ( 18 . 19 ) in diesel exhaust, comprising a device ( 8th ) for electrically charging the particles ( 18 . 19 ) and one downstream of the device ( 8th ) arranged for electrical charging deflection ( 15 . 16 ), with which the particles ( 18 . 19 ) to at least one in the flow direction of the gas stream ( 3 ) downstream measuring device ( 20 ) are deflected, characterized in that the deflection device ( 15 . 16 ) a magnetic field generating arrangement of a permanent magnet ( 16 ) and / or an electromagnet ( 15 ) whose magnetic effect ( 14 ) the particles ( 18 . 19 ) depending on their respective size different degrees from their normal trajectory and the at least one measuring device ( 20 ), whereby the measuring equipment ( 20 ) impinging particles ( 18 . 19 ) their respective charge to the measuring device ( 20 ) submit. Apparatus according to claim 1, characterized in that the magnetic field generating arrangement of a permanent magnet ( 16 ) and / or an electromagnet ( 15 ) the particles ( 18 . 19 ) deflects in a plane along which the measuring device ( 20 ) or the measuring equipment ( 20 ) in succession in the flow direction of the gas stream ( 4 ) are arranged. Device according to one of claims 1 or 2, characterized in that the magnetic field ( 14 ) for the deflection of the particles ( 18 . 19 ) is designed such that small particles ( 18 ), preferably in the range between 1 to 5 nm, stronger and larger particles ( 19 ), preferably in the range between 5 to 10 nm, are deflected more weakly. Device according to one of the preceding claims, characterized in that the magnetic field ( 14 ) the particles ( 18 . 19 ) perpendicular to the flow direction of the gas stream ( 4 ) distracts. Device according to one of the preceding claims, characterized in that before the arrangement of a permanent magnet ( 16 ) and / or an electromagnet ( 15 ) a gas flow limiting aperture ( 13 ) is arranged. Device according to one of the preceding claims, characterized in that the to the measuring device ( 20 ) discharged on the measuring device ( 20 ) impinging particles ( 18 . 19 ) a measure of the concentration of the particles ( 18 . 19 ) in the gas stream ( 3 . 4 ). Device according to one of the preceding claims, characterized in that only one measuring device ( 20 ) in the flow direction of the gas stream ( 4 ) behind the deflector ( 15 . 16 ) is arranged. Device according to claim 7, characterized in that the deflection device ( 15 . 16 ) the particles ( 18 . 19 ) deflects with a variable magnetic field effect from its trajectory. Device according to claim 8, characterized in that the variable magnetic field effect ( 15 ) is periodically changeable. Device according to claim 9, characterized in that the variable magnetic field effect ( 15 ) periodically sliding over a predetermined magnetic field strength range. Device according to claim 9, characterized in that the variable magnetic field effect ( 15 ) periodically scoring a predetermined magnetic field strength region in some areas. Device according to one of claims 7 to 11, characterized in that depending on the respective magnetic field strength ( 14 ) and the resulting deflection of the particles ( 18 . 19 ) the respective particle size of each on the one measuring device ( 20 ) depositing particles ( 18 . 19 ) is determinable. Device according to one of claims 1 to 6, characterized in that more than one measuring device ( 20 ) in the flow direction of the gas stream ( 4 ) is arranged one behind the other. Device according to claim 13, characterized in that the deflection device ( 15 . 16 ) the particles ( 18 . 19 ) at a substantially constant magnetic field effect ( 14 ) distracts from her trajectory. Device according to claim 14, characterized in that the different sized particles ( 18 . 19 ) at the substantially constant magnetic field effect ( 14 ) due to their inertia on different of the successively arranged measuring devices ( 20 ) deposit. Apparatus according to claim 15, characterized in that on each of the successively arranged measuring devices ( 20 ) deflected particles ( 18 . 19 ) of a certain size or size range from the gas flow ( 4 ) deposit. Device according to one of the preceding claims, characterized in that the resul magnetic field ( 14 ) a superposition of a constant magnetic permanent magnetic field ( 16 ) and an adjustable electromagnetic magnetic field ( 15 ). Device according to one of the preceding claims, characterized in that the cross-section ( 25 ) the device for the passage of the gas stream ( 4 ) in the region of the magnetic field effect ( 14 ) is rectangular in order to produce a high magnetic field strength in a relatively small air gap. Device according to one of the preceding claims, characterized in that the measuring devices ( 20 ) Heating devices ( 24 ), with which the impinging particles ( 18 . 19 ) preferably periodically burned down and the measuring devices ( 20 ) can be cleaned thereby. Device according to one of the preceding claims, characterized in that the device ( 8th ) for electrically charging the particles ( 18 . 19 ) an ionization device ( 11 ) having. Apparatus according to claim 20, characterized in that before and / or behind the ionization device ( 11 ) at least one aperture ( 7 . 13 ), which has only one focused gas stream ( 4 ). Device according to claim 21, characterized in that the diaphragm ( 7 . 13 ) the transmitted gas flow to a constant flow rate of particles ( 18 . 19 ) limited. Device according to claim 21 or 22, characterized in that the diaphragm ( 7 ) in front of the ionization device ( 11 ) has a supercritical nozzle. Device according to one of the preceding claims, characterized in that the device in bypass to the actual gas flow ( 3 ) and only a partial flow ( 4 ) of the gas stream ( 3 ) flows through the device. Apparatus according to claim 24, characterized in that the device via an isokinetic extraction device ( 5 ) to the main stream of the gas stream ( 3 ) is attached. Device according to claim 25, characterized in that the removal device ( 5 ) a part ( 4 ) of the gas stream ( 3 ), in which all particle sizes and distributions are distributed in the same way as in the original gas stream ( 3 ) available. Device according to one of claims 24 to 26, characterized in that the extracted subset ( 4 ) of the gas stream ( 4 ) only a small proportion of the total gas flow ( 4 ) includes. Device according to one of the preceding claims, characterized in that the device ( 8th ) for electrically charging the particles ( 18 . 19 ) a high voltage electrode ( 11 ) which is electrically isolated from the device ( 10 ). Device according to claim 28, characterized in that the high-voltage electrode ( 11 ) is arranged in a grounded region of the device, preferably a grounded pipe section. Device according to one of the preceding claims, characterized in that the device ( 8th ) for electrically charging the particles ( 18 . 19 ) charges with a simple electron charge. Device according to one of the preceding claims, characterized in that an evaluation device ( 22 ) functionally with the measuring devices ( 20 ), which is preferably based on amplifier circuits ( 21 ) the number and / or distribution of the impinging particles ( 18 . 19 ) or their charges on the various measuring devices ( 20 ) registers and evaluates. Device according to one of the preceding claims, characterized in that the evaluated signal ( 23 ) the particle number and / or the size distribution of the particles ( 18 . 19 ) as a control variable in the generation of the particles ( 18 . 19 ), in particular as a controlled variable in the exhaust gas control of a diesel engine is available. Device according to one of the preceding claims, characterized in that the evaluated signal ( 23 ) the particle number and / or the size distribution of the particles ( 18 . 19 ) can be used as a control value for a current particulate filtering. Device according to one of the preceding claims, characterized in that the measuring devices ( 20 ) are operable under an electrical bias. Device according to one of the preceding claims, characterized in that the device for retrofitting to existing producers of gas streams to be monitored ( 3 ), preferably usable on existing diesel engines. Device according to one of the preceding Claims, characterized in that the device as a measuring device for checking the particle number and distribution of the gas stream ( 3 ) in workshops or the like. Usable. Device according to one of the preceding claims, characterized in that the device can be calibrated gravimetrically is.