DE102017130981B3 - System for providing an aerosol - Google Patents

Abstract

A system for providing an aerosol comprises a particle generator (7) for generating a particle flow and a dilution system (8) for diluting the particle flow with dilution air. Downstream of the dilution system (8) is provided an outlet (11) and a particle supply device (24). Part of the flow of particles fed to the dilution system (8) is deliverable to the outlet (11), while another part of the flow of particulates supplied to the dilution system (8) is feasible to the particle supply means (24). In the dilution system (8) there is a pressure gradient to promote particle flow. In addition, a regulated proportional valve (26, 27) is provided between the dilution system (8) and the outlet (11), with which the pressure conditions in the dilution system (8) can be precisely adjusted.

Description

The invention relates to a system for providing an aerosol.

For emission monitoring of engines and vehicles, it is a legal requirement that the exhaust gases on a test bench or even under real conditions, e.g. on the road, and to investigate their composition in detail. Here, in addition to a variety of pollutant levels especially particulate matter of particular interest. The fine dust particles, for example, nanoparticles, can penetrate deeply into the lungs via the respiration and lead to considerable health impairments. In addition to the particles emitted by engines, particle emissions from other components, such as brake and tire abrasion, can be regulated in a similar manner in the future.

For detecting the particles, corresponding particle measuring devices are known, which are used in test stands or measuring systems equipped therefor. Not least due to legal regulations, particle measuring devices must be regularly maintained, checked and calibrated in order to ensure the required accuracy of measurements on a permanent basis. Examples of such legal regulations are, for example, UNECE Regulation No. 83, Rev. 5, series 05 or UNECE Regulation No. 49, Rev. 4, series 05 or the Global Technical Regulation (GTR) No. 15 etc. These regulations require, for example, a regular review of the systems every 12 months.

For the regularly required checking of particle measuring devices (test object), it is known to provide a particle generator which generates particles in a mass flow and transfers them to a carrier medium (air, nitrogen, etc.). With reference to the particle characteristics to be tested (particle concentration, number of particles, particle mass, opacity, etc.), this "aerosol" generated in this way is measured in parallel by a reference measuring device and also fed to the measuring device to be tested. By comparing the measurement results of the reference measuring device and the device to be tested, the device to be tested can be used, for example, as a reference device. be readjusted.

For the provision of the aerosol, it is usually necessary to dilute the aerosol generated by the particle generator. Thereby, changing external conditions, e.g. Air pressure or ambient temperature, but also not exactly reproducible operator influences (setting valves, rivers, etc.), leading to a change in the dilution effect and thus a change in the aerosol quality. The changing conditions may, in particular, lead to the aerosol to be provided by the system or a component in the system (eg classifier, reference measuring device) having variable and thus no longer constant or reproducible properties, which means the subsequent validation or calibration of the actual particle size. Measuring instruments difficult.

Although, due to the environmental influences changing measured values can often be corrected by appropriate correction calculations. An influence on the particle properties as well as on the working behavior of the relevant components, such as the particle generator, a classifier (also referred to as a classifier or classifier hereinafter) or a reference particle measuring device, can still be maintained to some extent.

From the DE 10 2014 104 849 A1 is a venturi thinner known, which is used in a particle generator for generating an aerosol. In a venturi thinner, particle-free air is passed through an annular gap concentrically disposed about an aerosol inlet nozzle where it creates a negative pressure. This negative pressure sucks through the aerosol inlet nozzle to an aerosol volume flow, which mixes in a mixing chamber with the particle-free air, so that the aerosol is diluted.

Another type of particle generator is in the US 4,764,057 A described.

The DE 10 2004 025 208 A1 deals with a method for determining characteristic properties of soot particles from combustion processes, which uses the determination of the blackening of a filter paper.

Finally, in the DE 36 17 232 A1 a device for generating a solid aerosol described by means of a rotating brush.

The invention has for its object to provide a system for providing an aerosol, in which (fully) automatically precisely defined and reproducible conditions for the generation and processing (dilution, classification, etc.) of a suitable aerosol or particle flow can be provided.

The object is achieved by a system for providing an aerosol with the features of claim 1. Advantageous embodiments can be found in the dependent claims.

The invention relates to a system for providing an aerosol, comprising a particle generator for generating a particle flow Dilution system downstream of the particle generator for diluting the particle flow with dilution air, an outlet downstream of the dilution system (for rejecting the unneeded particle flow, eg into a fume hood) and with a particle supply device downstream of the dilution system ( to provide the aerosol to be used). A portion of the particulate flow supplied to the dilution system is feasible to the outlet while another portion of the particulate flow is feasible to the particulate delivery device. Furthermore, a pressure measuring device is provided for measuring an actual value for the pressure at at least one point in the dilution system.

In the dilution system there is a pressure gradient, with a controllable proportional valve being arranged between the dilution system and the outlet. In addition, a control device is provided for adjusting the proportional valve as a function of the measured pressure value by the pressure measuring device and a predetermined pressure setpoint.

The dilution system is thus equipped with a device for detecting the pressure in the dilution system and a control device (control loop / control unit) with a pressure as a setpoint (pressure setpoint), the detected pressure as the actual value (pressure feedback) and the proportional valve as a manipulated variable. This design allows decoupling from the rest of the environment. The pressure in the dilution system can be adjusted independently of changing environmental conditions.

The particle generator produces an aerosol which, in the present system, can then be diluted in a completely controlled manner with respect to its pressures and flows. The dilution can - as will be explained later - one or more stages.

The particle generator is known per se in various embodiments and serves to produce particles in a polydisperse aerosol with a specific particle size distribution. The present system, because of its properties, is capable of cooperating with most of these common particle generators, e.g. within its design limits, to provide (regulate) any pressures and pressure gradients required to take the particles down to the dilution system (even with fluctuations in the aerosol flow).

Thus, in the system, the particle flow generated by the particle generator is passed through the dilution system. A portion of the diluted and conditioned by the dilution system in the desired manner and conditioned particle flow is fed to the particle supply device, through which the particle flow its original purpose, for example, a test bench or to be checked particle measuring instruments can be performed.

Another part of the particle flow can be led to the outlet. The particle flow is thus branched off from the particle flow coming from the particle generator. Optionally, the particle flow may already have been (partially) diluted in the dilution system.

Due to the consistently completed design of the particle-guiding system (in particular the controlled proportional valves) and by the control loops, it is possible to (automatically) adjust and regulate the conditions in the dilution system in a desired manner. In particular, it is possible, the pressure ratios in the dilution system always at a desired level (pressure setpoint) defined, and to keep constant, regardless of the ambient conditions such as ambient air pressure, ambient temperature, humidity, etc. Any location-related, but also changing environmental influences can be Balancing and thus decoupling from the environment by controlling the flow of particles to the outlet, as well as changing (interference) influences by components in the system.

The system allows the provision and dilution of an aerosol or even a particle-free gas flow under precisely defined conditions, whereby an influence due to environmental conditions (installation location, weather, air pressure, etc.) and other (disturbing) influences can be excluded or at least significantly reduced.

There is a pressure gradient in the dilution system. This means that the pressure gradient exists in particular between the inlet of the dilution system and a point of the dilution system located downstream of the inlet and thus drives the gas or aerosol flow. Downstream locations are in particular the connections to the outlet or the particle supply device.

With the aid of the pressure gradient it is possible to maintain the flow of the particle flow through the dilution system or even to control the flow / flow rates within the controllable pressure levels.

The pressure gradient may be effected, for example, by a pressure sink between the dilution system and the outlet. The pressure sink creates a negative pressure which acts on the dilution system and thus causes the particle flow from the particle generator through the dilution system. For example, between the dilution system with the corresponding proportional valve and the outlet from the system, a pump may be arranged which generates a vacuum and applies it to the dilution system. In this way, a mass flow is generated by the dilution system.

The generated with the help of the pump, negative pressure or negative pressure in conjunction with one or more other proportional valves and a suitable control and optionally volumetric flow meters or mass flow meters always equal negative pressure and thus the same conditions for the negative pressure dependent components (eg control of upstream allow dilution levels).

The output of the pump can be routed to the outlet into the environment or into a fume hood.

The pump may be used, for example, as a vacuum pump, in particular e.g. be designed as a rotary vane pump.

It is also possible to apply an overpressure (increased pressure) upstream from the dilution system, in particular at the particle generator, which then acts at the inlet of the dilution system, effects the pressure gradient and generates the mass flow through the dilution system.

Particle flow inside the dilution system is split at a suitable location so that part of the flow of particles flows to the particle delivery device and another part to the outlet.

The system can thus be completely decoupled from the environment. Only at the upstream particle generator on the one hand and on the downstream outlet on the other hand can connect to the environment exist. By contrast, the area of the dilution system is completely decoupled from the environment, so that environmental influences have no effect on the dilution effect inside the dilution system or on all components integrated in the system or coupled to the system (particle generator, classifier, mass flow meter, etc.).

The dilution stages are connected to ambient components exclusively by controlled manipulated variables (for example the proportional valves), which are regulated with appropriate setpoint specification and actual value measurement (device for detecting the pressure) as well as a control loop. This allows a consistent, independent of the environment and independent regulation of the pressures within the individual dilution stages (automatic, defined, precise, stable).
The control device which regulates the pressures in the dilution system by means of the proportional valve (or a plurality of proportional valves) can also be part of a higher-level control, eg a test rig control or the like. his. The respective desired values for the pressures can also be adjustable or stored in the control device.

The dilution can thus be carried out automatically under desired and precisely defined and reproducible conditions and, in particular, independent of variable external conditions, such as ambient temperature, air humidity, air pressure, installation location of the devices, etc. The large number of error influences on the dilution and all components can thus be reduced.

The dilution system may have a first dilution step and a second dilution step downstream of the first dilution step. It is also readily possible to provide further dilution stages in the dilution system.

The first dilution stage may be connected to the outlet via a first regulated proportional valve, while the second dilution stage may be connected to the outlet via a second regulated proportional valve. In this sense, each of the dilution stages provided in the dilution system can thus have its own regulated proportional valve leading to the outlet. Likewise, each of the dilution stages may have a unit for detecting the pressure in the dilution system and a control loop.

In particular, in the first dilution stage, a first pressure measuring device may be provided for measuring an actual value for the pressure at at least one point in the first dilution stage. Furthermore, in the second dilution stage, a second pressure measuring device may be provided for measuring an actual value for the pressure at at least one point in the second dilution stage.

In addition, the regulating device can be designed to set the respective first and second controlled proportional valve as a function of the actual pressure values measured by the respective pressure measuring devices and the respective predetermined desired pressure values.

By means of the individual proportional valves and controls assigned to the respective dilution stages, the pressure conditions inside the respective dilution stage can be adjusted or adjusted precisely and independently of the ambient conditions.

Regardless of whether a single-stage dilution or a multi-stage, for example two-stage dilution, should be made, the volumetric flows and the pressure levels of these rivers are so regulated that, for example, can be achieved ratios that correspond to defined constant standard conditions (usually 101.3 kPa - even at lower / deviating applied ambient pressures at the place of testing). Likewise, it is thus possible to achieve arbitrary pressure levels or to test a larger pressure range (e.g., stepwise).

In this way, the aerosol or the particle-free gas flow thus defined can be provided consistently for any measuring tasks, for example for the validation or calibration of a particle measuring device, without the properties changing due to variable environmental influences. It is therefore also possible for conditions to be generated at the supply device which otherwise would not be possible for the test object at the place of testing.

Irrespective of different flows provided by the aerosol source (particle generator) or different flows taken from the components to be tested or influenced by other components, the desired (equal) pressure in the respective dilution stage is always adjusted and any changes and disturbances are corrected. Thus, there are always defined, independent of the environment and other test conditions pressure conditions for the particle generator and the classifier, other accuracy-relevant components in the system and the test object and the reference.

In the first dilution stage, a pressure-controlled, environmental-sealed dilution may be performed that is not subject to ambient pressure. Independently of different flows provided by the aerosol source, the same pressure is thus always regulated in the dilution stage. This can be achieved always defined, separated from the environment and other test conditions pressure conditions.

Also in the second dilution stage, a pressure-controlled, completed by the environment dilution can take place, so that correspondingly defined, separated from the environment and the other test conditions pressure conditions are achieved.

Since the pressures in the two dilution stages can thus be regulated independently of the ambient conditions, it is also possible to control the flow between these stages, for example also by means of an intermediate particle classifier (eg a DMA - Differential Mobility Analyzer) To regulate the pressure difference between the two dilution stages, so that the thus adjusting flow reaches the desired value.

Thus, a classifier may be arranged between the first dilution stage and the second dilution stage for classifying the particles in the particle flow. For example, the classifier may achieve particle size classification or size selection. Corresponding devices are known, for example a DMA. This makes it possible to eliminate a monodisperse aerosol with a desired particle diameter from the aerosol generated by the particle generator. Depending on the equipment of the system, it is thus possible to obtain a model aerosol with particles of defined size (classifier) and with a set concentration (dilution) downstream of the dilution system.

The pressures in the two dilution stages can be regulated individually. In this way, the pressure gradient between the two dilution stages can be adjusted. For example, in the first dilution stage, a pressure value of 102 kPa can be set while in the second dilution stage a value of 101 kPa is set. Likewise, the first dilution stage can be adjusted to a pressure of 100 kPa, while the pressure in the second dilution stage can reach a higher value, for example 101 kPa, whereby the pressure increase can be assisted by a pump explained below.

Between the first dilution stage and the second dilution stage, a pump, in particular a Venturi pump can be provided. In particular, the venturi pump is capable of producing an additional positive pressure gradient between the first dilution stage and the second dilution stage. This also makes it possible, for example, to increase the pressure from one to the next dilution stage. For example, in the first dilution stage, a pressure of 90 kPa may be set, while in the second dilution stage an increased pressure in a variable range of 90-110 kPa is needed. This (variable) pressure increase can be effected by the Venturi pump.

At the same time, the Venturi pump can lead to pre-dilution because the ambient or dilution air supplied to it enters the gas flow.

In particular, the venturi pump may be provided between the classifier and the second dilution stage. The additional positive pressure gradient generated by the Venturi pump allows the flow to be regulated by the classifier (DMA).

A control device may be provided for regulating a gas flow serving as a set value between the first dilution stage and the second dilution stage. In this case, a gas flow measuring device may be provided between the first dilution stage and the second dilution stage, for measuring an actual value for the gas flow that can be fed to the regulating device. By the control device, the pump power of the Venturi pump can be adjusted so as to influence the actual value such that it approaches the desired value.

Thus, to control the flow through the classifier or the flow between the two dilution stages (set point), the actual value is the measured value of the gas flow measuring device (for example volume flow meter or mass flow meter), e.g. may be placed in the classifier or at another suitable location between the two dilution stages. The manipulated variable is the pumping capacity of the Venturi pump, which is used e.g. can be adjustable by a controlled proportional valve. The proportional valve may be provided in an ambient air supply line for supplying ambient air for operating the venturi pump, as will be explained later. By adjusting the pumping power of the Venturi pump, it is thus possible to adjust the gas flow between the two dilution stages in the desired manner and in particular also to cause an increase in pressure. By selecting the desired pressure values, a defined pressure gradient can be established between the dilution stages.

The arrangement of the classifier (also referred to as a classifier or classifier) and the Venturi pump between the first dilution stage and the second dilution stage thus allows the settings for the first dilution stage to remain unchanged during operation (and thus the conditions, for example for the particle generation, dilution and classification), while the settings (and thus eg the pressures) for the second dilution stage can be changed in a defined manner (and thus also, for example, the conditions of the test specimen).

The venturi pump can be particularly advantageous because it does not change the aerosol flow and in particular no particles can be deposited.

An ambient air supply may be provided, with an ambient air supply leading to the second dilution stage, for supplying ambient air to the second dilution stage. With the help of the ambient air serving as dilution air, the desired dilution effect can be achieved in the second dilution stage. Analogously, an ambient air supply can also be provided for the first dilution stage.

The term "ambient air" serving as dilution air is to be understood broadly in this context. The ambient air may be air from the environment, e.g. is supplied as compressed air. However, it is also possible to use e.g. Nitrogen serve as "ambient air".

For operation of the venturi pump, it may be particularly suitable that a further ambient air supply line is provided for supplying ambient air for operating the venturi pump.

In the leading to Venturi pump ambient air supply line, a mass flow measuring device and / or a proportional valve may be provided to adjust the flow of air to the Venturi pump and thus their pumping or pumping power.

In the ambient air supply line leading to the second dilution stage, a mass flow measuring device and a proportional valve can also be provided in order to adjust the flow of the ambient air to be supplied.

The ambient air supply line for the venturi pump may branch off from the ambient air supply line for the second dilution stage at a location downstream of its mass flow meter, which branch may be upstream of the proportional valve provided in the ambient air supply line for the second dilution stage.

This arrangement allows the ambient air to be supplied via the first ambient air supply line. Part of the ambient air is diverted with the aid of the second ambient air supply line after the measurement (or also regulation) of the volumetric flow and fed to the Venturi pump in order to drive it. The other part is fed via the first ambient air supply line directly to the second dilution stage as dilution air. The ambient air part used to operate the Venturi pump is fed, also passes after passing through the Venturi pump in the second dilution stage and rejoins together with the other ambient air part, which was supplied via the first ambient air supply line. In sum, therefore, the originally supplied ambient air remains the same, since the first divided dilution air streams are brought together again in the second dilution stage. This (total) dilution air flow can be determined by the mass flow measuring device previously arranged in the first ambient air supply line. With this configuration, the total dilution air flow thus always remains constant - for example, during changes in the flow into the Venturi pump (eg during the above-described active automatic control of the flow through the classifier by Venturi pump power). A change in the dilution factor in the second dilution step is thereby avoided.

A bypass to the outlet may be provided between the venturi pump and the second dilution stage and / or between the classifier and the second dilution stage. In particular, the bypass allows a portion of the supplied aerosol stream to be removed and discarded via the outlet. This can be adjusted by a proportional valve in the bypass. This is especially helpful if the supplied aerosol stream is highly concentrated and in the second dilution stage a very strong dilution air flow would have to be achieved in order to achieve the desired particle concentration at the end. By discharging a portion of the highly concentrated aerosol stream through the bypass, the remaining aerosol stream entering the second dilution stage can be more dilute, even though the dilution air fed to the second dilution stage should not be increased in volume.

The bypass causes an influence on the mass flow in the second dilution stage, since a part of the originally supplied mass flow is rejected via the outlet. For clarification of the measurement, it can therefore be meaningful that a mass flow measuring device is likewise provided in the bypass, in order to compensate for the mass flow in the second dilution stage on the basis of its measured value.

For example, there is often a requirement on a test bench to vary the particle concentration greatly for a linearity test of the test items (the equipment to be tested), which is usually realized by a strong increase in the dilution air flow and an associated high dilution of the particle flow (and thus actually unintentional strong changes eg the pressure and turbulence conditions in the dilution). In this case with bypass, to reduce the particle concentration, a corresponding portion of the aerosol downstream from the venturi pump (or classifier) and before the second dilution stage can be branched off and discarded via the bypass.

The particle providing means provided downstream of the second dilution stage may comprise a particle supply line for guiding the aerosol stream leaving the second dilution stage to a device to be supplied with the aerosol stream. The device may, for example, be a particle meter to be tested. In particular, the particle supply line can be coupled to a connecting device, which will be explained below, to which the device to be tested can be connected.

The system for providing an aerosol can be coupled to a device that can be connected to the system to be tested, wherein a connection device can be provided for connecting the device to be tested.

The device under test (e.g., particulate measurement systems in test benches) can be easily connected to the connector. The connection device can thus provide the necessary or sensible connection options in order to be able to connect the device to be tested to the system. Thereby, e.g. Hose couplings, connectors, screw connections, bayonet connections may be present. In addition, the corresponding conduction paths are provided to carry out the mass flows.

The connection device can have a plurality of lines to which the device to be tested can be connected.

The entire system may be in the form of a mobile unit. In particular, the unit can be accommodated in a frame, frame or cabinet which can also be displaced or, for example, moved on rollers. Thus all components can be accommodated in the rack or cabinet so that the system can also be routed to various devices and systems to be tested. It is therefore not necessary to take each time consuming construction and removal measures to check various devices to be tested.

Known dilution systems usually have an unregulated, closed scheme or an open, overflowing scheme. With closed systems, special care must be taken by means of manual adjustment that all volume flows match one another, so that a balance between the incoming and outgoing mass flows can be achieved. The currents are partly manually adjusted in order to avoid mutual interference. Even small changes in the components, for example due to a pump that does not deliver uniform pressure, can have a negative effect on the whole system, affecting the accuracy of the dilution. These changes usually need to be manually detected and corrected.

In contrast, it is provided in the system according to the invention that all parameters are measured automatically and subsequently adjusted automatically.

Overflow systems are open towards an outlet or the atmosphere. However, since the environmental conditions are variable, appropriate feedbacks are made to the gas flows in the system, which can also affect the accuracy.

In the system according to the invention, said problems can be solved by (its design with) a combination of venturi pumps, mass flow meters, proportional valves and e.g. a final provided vacuum pump and pressure measurement and control loops are avoided, so that it is possible to provide aerosol stable and independent of the external conditions and other disturbing influences.

• 1 eine schematische Übersicht über ein System zum Validieren von Aerosol- und Flussmessgeräten, mit einem erfindungsgemäßen System zum Bereitstellen eines Aerosols; und
• 2 eine detailliertere Teildarstellung des Systems zum Bereitstellen eines Aerosols von 1.

These and further advantages and features will be explained in more detail below by means of examples with the aid of the accompanying figures. Show it

• 1 a schematic overview of a system for validating aerosol and flow meters, with a system according to the invention for providing an aerosol; and
• 2 a more detailed partial view of the system for providing an aerosol of 1 ,

1 shows a calibration and validation system 1 for validating aerosol and flow meters in a device to be tested connected to the system. For the calibration and validation system 1 For example, the present system for providing an aerosol can be used, which is described below with reference to 2 is explained.

Most components of the system 1 are in a tempered cabinet 2 accommodated. The cupboard 2 For example, it can be mounted on rollers and thus easily movable to move it to the desired location for the respective calibration or validation operations.

At one on the cabinet 2 easily accessible connection device 3 is a device to be tested 4 connected. For this purpose, at the connection device 3 one or more lines may be provided, which - in the simplest case - have plug-in couplings, so that the corresponding line connections only need to be plugged.

The device to be tested 4 is over the connection device represented by a symbolic box 3 with the system 1 in the cabinet 2 connected.

If necessary, at the connection device 3 even more devices 5 , in particular other devices to be tested 4 be connected.

Furthermore, a control system controlling the entire system 6 intended. The control 6 on the one hand on the device to be tested 4 be provided. But it can also be part of the system 1 and in this case also in or on the cabinet 2 be housed.

The control 6 is capable of all components of the system 1 to control, for example, to perform different modes automatically. The modes may be, for example, an aerosol validation mode and a flow validation mode. It is also possible to switch over the various operating modes by means of the controller 6 done automatically. It is thus possible after connecting the device under test once 4 with the system 1 via the connection device 3 Automatically perform all calibration and validation operations in one go, without the need for any operator to undertake any change or even refurbishment in between. The different steps are controlled by the controller 6 performed sequentially without the need for assistance from an operator.

The control 6 In particular, it can also be designed to carry out the specific measuring and control tasks that occur in the system according to the invention for providing an aerosol.

Below is the system 1 and the main components are explained:

A per se known particle generator 7 produces a polydisperse aerosol with a certain particle size distribution. Because of one in the system 1 existing pressure gradient, the Example by one or more in 1 not shown pumps can be generated, the particle aerosol flow flows into a dilution system 8th , in which the particle flow can be conditioned and diluted. This is the dilution system 8th dilution air 9 supplied from the outside. In addition, a classifier 10 be provided, which classifies the particles more precisely to be able to excrete a monodisperse aerosol with desired particle diameter can. The classifier 10 For example, it may be a per se known differential mobility analyzer (DMA) for particle size classification and size selection. The desired particle selection can be performed using an electrostatic classification.

In the dilution system 8th may be provided one or more, in particular two dilution stages. The design takes place as needed for concentration adjustment and flux increase.

The invention relates to the system for providing the aerosol and thus in particular the design and the interaction of the particle generator 7 and the dilution system 8th , This system will be later based on 2 explained in more detail.

Downstream of the dilution system 8th Part of the mass flow becomes an outlet 11 while another part (reference numeral 24 ) as a model aerosol to a ball valve switching device 12 (also: ball valve unit) is performed. The ball valve switching device 12 is part of a switching device for switching the mass flow depending on the desired mode.

The ball valve switching device 12 allows a connection of a reference particle measuring device 13 , in the example shown, two reference particle measuring devices, a first reference particle measuring device 14 and a second reference particle gauge 15 having. The one to the reference particle gauges 14 . 15 guided mass flow can through a flow divider, not shown 13a be diverted.

The reference particle gauges 14 . 15 For example, you can use a Condensation Particel Counter (CPC) calibration that uses the count of counters to determine the count rates of the connected device being tested 4 compared to the reference particle measuring devices 14 . 15 is compared.

The other part of the model aerosol, which is not the reference particle measuring device 13 is passed, passes through the connection device 3 to the device under test 4 and there eg to the particle measuring device inside the device to be tested 4 , By comparing the counts of the reference particle gauges 14 . 15 on the one hand and the device under test 4 or a particle sensor therein, the latter can be validated or calibrated. Thus, either the meter is in the device under test 4 alone against the reference particle measuring devices 14 . 15 validated or calibrated or it becomes the particle dilution and particle losses in the device under test 4 in the whole or in detail with measured.

Other measuring methods are also possible, for example a VPR calibration (Volatile Particle Remover) for detecting particle losses via components in the system to be tested via corresponding count rates at the input and output of the component (change through ball valve changeover device).

The first mode described above with its various tests may also be referred to as aerosol validation mode.

For the (automatic) execution of the flow validation mode serving as a second operating mode, the controller switches 6 the ball valve switching device 12 in a suitable manner, so that a connection of a terminal of the device under test to a solenoid valve unit 16 is created. In addition, direct gas paths between device to be tested and solenoid valve unit may be provided. The solenoid valve unit 16 has solenoid valves that can open and close different flow paths, depending on the control provided by the controller 6 , With the solenoid valve unit 16 is a reference mass flow meter serving as a reference gas flow meter 17 coupled in terms of flow, in which one or more later described reference mass flow measuring devices are provided.

The one in the flow validation mode by the reference mass flow meter 17 Guided gas or mass flow is measured there precisely and then to a - through the valve units (of the test system and the device to be tested) - serially connected flow measuring component in the device under test 4 led, where also takes place a measurement of this mass flow. In this way, this can be done in the device being tested 4 provided and there serving as a gas flow meter mass flow device by comparison with the results of the reference mass flow meter 17 be validated or calibrated. Sequentially, a selection or all of the flow measurement components in the device under test can be checked.

In the 1 shown components for providing a suitable aerosol, in particular the particle generator 7 , the dilution system 8th and optionally also the classifier 10 are part of a system for providing an aerosol based on 2 will be explained in detail.

It should be noted that the use of the inventive system for providing an aerosol in the in 1 shown calibration or validation only represents an application example. The system for providing an aerosol can also be readily used in other systems where an aerosol of defined, consistent quality and consistent properties is required. The use of the system of 2 in a calibration or validation system 1 thus serves only the explanation, but not a limitation of the usability.

2 shows a more detailed structure of the system of 1 used system for providing an aerosol.

The particle flow from the particle generator 7 enters a first dilution stage 18 where ambient air is used as dilution air over a particle conditioner 19 is supplied. For better illustration is in 2 the dilution air flow is represented by bordered arrows, while the aerosol flow is symbolized by solid black arrows.

Downstream of the first dilution stage 18 is the classifier 10 (optional) provided behind which a venturi pump 20 to generate on demand a particular positive pressure gradient in the dilution system 8th is provided.

Downstream of the venturi pump 20 is a second dilution step 21 arranged. The dilution system 8th thus indicates the first dilution step 18 , the classifier 10 , the venturi pump 20 and the second dilution step 21 on.

For generating an aerosol stream in the dilution system 8th and a necessary pressure gradient is a pump 22 , For example, a vacuum pump such as a rotary vane pump, provided a mass flow to the outlet 11 promotes. The pump 22 has appropriate connections to the first dilution stage 18 and to the second dilution step 21 , as explained later, but also to the bypass 21 - 33 and optionally to another ambient air supply 28 (Pump vacuum control).

In addition, further supply of ambient air via a pressure reducer 23 and various mass flow meters (MFM) may be provided to monitor the respective mass flows. Thus, a complete control of the mass or aerosol flows is possible, so that finally a fully defined and controlled model aerosol flow in a particle delivery line 24 for further use (eg to the in 1 shown ball valve switching device 12 (Ball valve unit)) is promoted. The model aerosol flow in the particle delivery line 24 can also z. B. directly to the connection device 3 ( 1 ) and used there for further use.

The pump 22 is via a vacuum line 25 with the dilution system 8th or the dilution stages 18 and 21 in the dilution system 8th connected. In particular, each dilution stage 18 . 21 via a proportional valve with the vacuum line 25 connected, namely the first dilution stage 18 via a first regulated proportional valve 26 and the second dilution step 21 via a second regulated proportional valve 27 ,

For fine adjustment of the negative pressure or negative pressure in the vacuum line 25 is also an ambient air supply 28 provided in the one (regulated) ambient air proportional valve 29 is arranged.

Using the controlled proportional valves 26 . 27 . 29 and in 2 Not shown, but each provided pressure measuring devices thus the individual mass flows and pressures can be very precisely influenced and regulated to adjust the properties of the aerosol stream in the desired manner.

To control the various proportional valves and thus to regulate the individual pressures, a control device may be provided which, for example, also part of a higher-level control, eg a test rig control or the like. can be. For example, the controller is also suitable as a controller 6 in 1 , The respective desired values for the pressures can also be adjustable or stored in the control device.

Upstream of the pump 22 can also have a buffer tank 30 be arranged to allow any pressure fluctuations due to the pump 22 compensate.

Between the venturi pump 20 and the second dilution step 21 is a bypass 31 to the vacuum line 25 intended. In the bypass 31 is a bypass proportional valve 32 and a mass flow meter 33 arranged. Using the bypass 31 it is possible to discard a defined part of the aerosol stream, if a particularly high dilution in the second dilution step 21 should be achieved. The discarded part of the aerosol stream may be in the second dilution step 21 be compensated by additional dilution air again.

As already explained above, ambient air (dilution air) can be supplied via further feeds. For this purpose, one is to the second dilution step 21 leading ambient air supply 34 provided in which the pressure reducer 23 can be arranged. Downstream of the pressure reducer 23 may be a mass flow meter 35 be provided.

The ambient air supply line 34 conducts ambient air via a proportional valve 36 to the second dilution step 21 ,

From the to the second dilution step 21 leading ambient air supply 34 branches another ambient air supply 37 , with a mass flow measuring device 38 and a proportional valve 39 from. This additional ambient air supply 37 leads to the venturi pump 20 to get an airflow to the venturi pump 20 to direct the pumping action in the venturi pump 20 drives and gets in the venturi pump 20 with the aerosol stream from the classifier 10 mixed. In particular, the over the other ambient air supply 37 supplied dilution air to operate the Venturi pump 20 be used.

The ambient air flow is then passed over to the second dilution stage 21 leading ambient air supply 34 fed. Part of the ambient air flow is via to the venturi pump 20 leading further ambient air supply 37 diverted to operate the Venturi pump 20 used and in the second dilution stage 21 guided. The remaining part of the ambient air flow is via the ambient air supply line 34 directly into the second dilution stage 21 led, where the ambient air (partial) flows reunite, so that the mass flow measuring device 35 certain total air volume remains unchanged.

Upstream of the proportional valve 36 and downstream of the diversion to the venturi pump 20 leading ambient air supply 37 may be in the second dilution step 21 leading ambient air supply 34 another, in 2 Mass flow measuring device, not shown, may be provided.

Due to the different proportional valves, the pressure levels in the individual volume flows can be precisely adjusted. So it is possible with the help of the pump 22 and the ambient air proportional valve 29 the pressure level of the volume flow in the first dilution stage 18 with the help of the first regulated proportional valve 26 adjust. The flow rate to the classifier 10 can thus be kept at a constant level, even if the volume flows from the particle generator 7 vary.

That of the classifier 10 upcoming aerosol will be in the venturi pump 20 with dilution air from the ambient air supply lines 34 . 37 mixed. The volume flows of this ambient air supply are by appropriate volumetric flow meter (mass flow meter 38 ) and the proportional valve 39 regulated.

The venturi pump 20 therefore provides a precise and known dilute aerosol volumetric flow rate to the second dilution step 21 where a further dilution with additional dilution air (which also by mass flow meter and the proportional valve 36 is regulated) takes place.

By driving the venturi pump 20 It is also possible to control the gas flow between the two dilution stages 18 . 21 to set to a desired value. For this purpose, between the two dilution stages 18 . 21 one in 2 Gas flow measuring device not shown may be provided which serves to detect an actual value. The specified via a control device setpoint can then by changing the pump power of the Venturi pump 20 with the help of the regulated proportional valve 39 be achieved.

A further reduction in the number of particles or particle mass in the aerosol can be achieved by means of the bypass 31 be achieved.

The pressure level in the second dilution step 21 is dependent on the incoming volume flows by means of the second proportional valve 27 and the ambient air proportional valve 29 regulated, so that a constant volume flow 24 can be supplied with the model aerosol.

Claims (13)

A system for providing an aerosol, comprising - a particle generator (7) for generating a particle flow; - a dilution system (8) arranged downstream of the particle generator (7) for diluting the flow of particles with dilution air; - an outlet (11) provided downstream of the dilution system (8); and with - a particle providing means (24) provided downstream of the dilution system (8) for providing the aerosol for further use; wherein - a portion of the dilution system (8) supplied particle flow to the outlet (11) is feasible and another part of the dilution system (8) supplied particle flow to the particle supply means (24) is feasible; - A pressure measuring device is provided for measuring an actual value for the pressure at at least one point in the dilution system (8); - a regulated proportional valve (26, 27) is provided between the dilution system (8) and the outlet (11); and wherein - a control device is provided for adjusting the proportional valve (26, 27) in dependence on the pressure measured by the pressure measuring device and a predetermined pressure setpoint. System after Claim 1 in which - the dilution system (8) has a first dilution stage (18) and a second dilution stage (21) downstream of the first dilution stage (18); - The first dilution stage (18) via a first controlled proportional valve (26) is connected to the outlet (11); and wherein - the second dilution stage (21) is connected to the outlet (11) via a second regulated proportional valve (27). System after Claim 2 in which - a first pressure measuring device is provided in the first dilution stage (18) for measuring an actual value for the pressure at at least one location in the first dilution stage (18); and wherein - in the second dilution stage (21) a second pressure measuring device is provided for measuring an actual value for the pressure at at least one location in the second dilution stage (21). System after Claim 3 wherein the regulating device is designed to set in each case the first and the second controlled proportional valve (26, 27) as a function of the actual pressure values measured by the respective pressure measuring devices and respective predetermined pressure setpoints. System according to one of Claims 2 to 4 in which a classifying device (10) is arranged between the first dilution stage (18) and the second dilution stage (21) for classifying the particles in the particle flow. System according to one of the preceding claims, wherein for the generation of a pressure gradient in the dilution system (8) arranged between the dilution system (8) and the outlet (11) pressure sink, in particular a pump (22) is arranged. System according to one of Claims 2 to 6 wherein between the first dilution stage (18) and the second dilution stage (21) a pump, in particular a Venturi pump (20) is provided. System after Claim 7 in which - a control device is provided for regulating a gas flow serving as a set value between the first dilution stage (18) and the second dilution stage (21); a gas flow measuring device is provided between the first dilution stage (18) and the second dilution stage (21), for measuring an actual value for the gas flow that can be supplied to the regulating device; and wherein - by the control means the pumping power of the Venturi pump (20) is adjustable to influence the actual value such that it approaches the desired value. 9. System according to one of Claims 2 to 8th wherein an ambient air supply is provided, with an ambient air supply line (34) leading to the second dilution stage (21), for supplying ambient air to the second dilution stage (21). System after Claim 9 wherein a further ambient air supply line (37) is provided for supplying ambient air for operating the venturi pump (20). System after Claim 10 in which - a mass flow measuring device (35) is provided in the ambient air feed line (34) leading to the second dilution stage (21); and wherein - the ambient air supply line (37) leading to the venturi pump (20) branches off from the ambient air supply line (34) leading to the second dilution stage (21) at a location downstream of the mass flow meter (35). System according to one of Claims 7 to 11 in that a bypass (31) to the outlet (11) is provided between the venturi pump (20) and the second dilution stage (21) and / or between the classifier (10) and the second dilution stage (21). System according to one of Claims 2 to 12 wherein the particle supply means provided downstream of the second dilution stage (21) comprises a particle supply line (24) for guiding the second dilution stage (21) leaving aerosol stream to a device to be supplied with the aerosol stream.

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