WO2020074643A1

WO2020074643A1 - Cleaning and/or testing a gas-permeable item for use in the treatment of exhaust gas from an internal combustion engine

Info

Publication number: WO2020074643A1
Application number: PCT/EP2019/077478
Authority: WO
Inventors: Hanspeter Mayer
Original assignee: Ceramex Ltd
Priority date: 2018-10-10
Filing date: 2019-10-10
Publication date: 2020-04-16
Also published as: EP3636889A1

Abstract

The invention concerns a process for cleaning and/or testing a gas-permeable item suitable for use in the treatment of exhaust gas from an internal combustion engine, in particular a filter (3) or catalytic converter (2) in a motor vehicle. The item for said exhaust-gas treatment is arranged in a housing (1) with a gas inlet (4) and a gas outlet (5) in such a way that exhaust gas fed into the housing (1) via the gas inlet (4) at least in part passes the item suitable for exhaust-gas treatment before the exhaust gas leaves the housing (1) via the gas outlet (5). In order to achieve a particularly high level of efficiency, a provision is made according to the invention for a line (17) from a device to be connected to the gas outlet (5) and a further line (17) from the device to be connected to the gas inlet (4), whereupon using the device a fluid is led through the item via the lines (17) in order to test and/or clean the item. Furthermore, the invention concerns a device for the cleaning and/or testing of a gas-permeable item suitable for use in the treatment of exhaust gases from an internal combustion engine, in particular a filter (3) or catalytic converter (2) in a motor vehicle. The item for said exhaust-gas treatment is arranged in a housing (1) with a gas inlet (4) and a gas outlet (5) in such a way that exhaust gas fed into the housing (1) via the gas inlet (4) at least in part passes the item before the exhaust gas leaves the housing (1) via the gas outlet (5).

Description

Cleaning and/or testing a gas-permeable item for use in the treatment of exhaust gas from an internal combustion engine

The invention concerns a process for cleaning and/or testing a gas-permeable item suitable for use in the treatment of an exhaust gas from an internal combustion engine. The item for said exhaust-gas treatment is arranged in a housing with a gas inlet and a gas outlet in such a way that an exhaust gas fed into the housing via the gas inlet at least in part passes the item before the exhaust gas leaves the housing via the gas outlet.

Furthermore, the invention concerns a device for the cleaning and/or testing of a gas-permeable item suitable for use in the treatment of an exhaust gas from an internal combustion engine, in particular a filter or catalytic converter in a motor vehicle. The item for said exhaust-gas treatment is arranged in a housing with a gas inlet and a gas outlet in such a way that an exhaust gas fed into the housing via the gas inlet at least in part passes the item before the exhaust gas leaves the housing via the gas outlet.

A variety of processes and devices for the method of cleaning and testing of such items that, for example, are used in the treatment of exhaust gas from a motor vehicle, in particular filters, such as particulate filters, and catalytic converters, that was described at the beginning have emerged from the currently best-available technologies. Such items are commonly fixed within a housing in the exhaust tract of a motor vehicle. In order to clean and test such particulate filters, catalytic converters and the associated sheet metal parts using the processes of the currently best- available technologies, they are removed from the housing or a so-called canning and, following the cleaning or testing, are reinstalled in a housing, whereupon the items can once again be used for exhaust-gas treatment. This has proven to be very inefficient and expensive, especially since the housing is in most instances damaged during disassembly and items thus subsequently must be installed into a new housing. In addition, opening the housing frequently leads to leakages and structural weakening. This is the starting point for the invention. The task of the invention is to define a process such as is described at the beginning, which can be implemented

particularly efficiently.

In addition, a device such as is described at the beginning is to be defined, with which a process for cleaning and/or testing such an item can be carried out particularly efficiently.

According to the invention, the first task is accomplished by a process such as is described at the beginning, in which a line from a device is connected to the gas outlet and a further line from the device is connected to the gas inlet, whereupon using the device a fluid is fed through the item via the lines in order to test and/or clean the item.

As part of the scope of the invention it was identified that the laborious

disassembling of the item from the housing and re-installing of the item into the housing could be omitted if the cleaning and/or testing of the item were to take place in the housing. For this, a device is airtightly connected to the housing using lines, whereupon a fluid is transported through the lines into the housing and through the item using the device. Said fluid can take the form of a cleaning fluid and/or testing fluid in order to clean the item or record a quality of the item by flowing through it, in which one or more status values of the fluid or test fluid respectively are recorded before and after passing through the item. These status values, which can be used to assess a quality of the item or for testing respectively, can, for example, be a pressure, a particle load, a chemical composition and similar, which are measured or known prior to application to the item and are compared with the corresponding figures of the fluid once it has passed through the item. During the testing and/or cleaning process the item thus remains in the housing, in which it is also installed for normal operation in a motor vehicle. In order to clean the item, the fluid can take the form of a cleaning fluid, using in particular the density, pressure and temperature differences in the fluid. For example, the fluid can be made up of air or contain air. It goes without saying that the process can, at the same time, be used for both a single item as well as for multiple items arranged in the housing. Further, the process can, of course, also be implemented with housings that have multiple gas inlets and/or multiple gas outlets. It can then be provided that individual gas inlets or gas outlets are sealed in order to carry out the process. Alternatively, lines can, of course, be connected to all gas inlets and gas outlets in order to direct a cleaning and/or test fluid through the item or items.

It is beneficial if the item is cleaned using a cleaning fluid, which is introduced into the housing via the gas outlet, whereupon the cleaning fluid passes through the item in order to clean the item, whereupon the cleaning fluid flows out of the housing via the gas inlet. The fluid can contain cleaning fluid or be composed entirely of cleaning fluid.

It has become evident that relevant items such as filters, in particular particulate filters for diesel- or petrol-powered passenger vehicles, or catalytic converters can be cleaned particularly easily if a cleaning fluid is applied in precisely the opposite direction to that of exhaust gas flowing through the corresponding item during normal operation. For example, the cleaning fluid, which flows through the item in the opposite direction to that of exhaust-gas flow, can loosen contaminants located on the surfaces of the filter or convert them through a chemical reaction and then flush them out of the housing via the gas inlet, the same gas inlet through which exhaust gas flows into the housing under normal operation. Using the process according to the invention, the item can thus remain in the housing throughout the cleaning process.

In principle, the housing which is normally made of at least one metal can also be mounted in the exhaust tract of a motor vehicle. In this case, all that needs to be ensured is that the cleaning fluid flowing out of the gas inlet can escape. The housing can, of course, also be removed from the vehicle along with the items located within it in order to clean the items, which are commonly made of ceramic or metal and often have a honeycomb structure, at a location away from the vehicle. Thus, a provision may be made so that - prior to the cleaning and/or testing - the housing is removed from the exhaust tract of a machine with an internal combustion engine, in particular of a motor vehicle, in which the housing or rather the items for exhaust-gas treatment arranged in the housing were used for exhaust-gas treatment before cleaning and/or testing. Here, the housing is usually removed from the machine or motor vehicle respectively so the testing and/or cleaning can take place at a location away from the vehicle. In this case, the device for performing the process does not need to be transported to the machine in which the housing for exhaust-gas treatment is arranged.

However, a provision may also be made so that - during the cleaning and/or testing - the housing is arranged in an exhaust tract of a machine with an internal combustion engine, in particular of a motor vehicle, in which the housing or rather the items arranged in the housing were used for exhaust-gas treatment before the cleaning and/or testing.

In this case, the cleaning and/or testing can be performed directly at the machine and directly at the motor vehicle respectively, for example in a workshop or site, so that the laborious removal of the housing from the exhaust tract can be omitted.

Thus, the cleaning and/or testing of the items arranged in the housing, which have been contaminated through the treatment of exhaust gas in the exhaust tract of this machine prior to cleaning, and of the exhaust tract respectively can be achieved particularly easily. To this end, a cleaning aperture is normally provided in the exhaust tract upstream of the first item to be cleaned and/or tested in the direction of exhaust-gas flow or such an aperture is made, whereupon a line is connected to the cleaning aperture of the exhaust tract and thereby at least indirectly with the gas inlet of the housing, whilst a second line is connected to the exhaust end pipe of the motor vehicle or another aperture downstream of the housing in order to enable the flow of a testing and/or cleaning fluid through the one or more items whereby these are cleaned and/or tested in the process according to the invention.

This means, only one gas inlet and one gas outlet of the housing or one gas inlet aperture and one gas outlet aperture respectively need to be made accessible in order to supply the cleaning and/or testing fluid at one end and to lead away and analyse the contaminated fluid or rather the processing or testing gas after passing through the items or the objects to be tested at the other. Consequently, when cleaning is performed at the machine or at the vehicle, the device is usually brought to the machine or vehicle and the quality improvement is made directly at the machine. This may be particularly advantageous with large machines that are either difficult to move or not licensed for road traffic or not mobile at all.

The cleaning fluid may take the most different forms. It is beneficial if the cleaning fluid contains air or is made up of air, in order to implement the process particularly economically. In order to achieve effective cleaning, the cleaning fluid is usually moved through the item or items and, because of the flow and/or preparation, may have different density, pressures, and/or temperatures whilst passing through the item or items.

It is easily possible to clean the item or items in a particularly gentle way if the cleaning fluid is entirely gaseous. It has been shown, for example, that the cleaning of relevant items with water particularly washes out or damages the coatings that are crucial to the function of the item or items. In particular, this concerns vanadium, iron-zeolite, and copper-zeolite coatings which would be damaged by cleaning the item with water, so that following cleaning the catalytic reactivity would not be given any more or only to a very limited extent.

It is particularly advantageous if the cleaning fluid is dried before it is applied to the item. This reliably prevents damage to the coatings. In addition, this prevents a filter or catalytic converter substrate from absorbing moisture from the cleaning fluid.

The preferred provision is that the cleaning fluid contains a first fluid and a second fluid and that the second fluid is preferably added to the first fluid via a magnetic valve before the cleaning fluid is led into the item. For example, in addition to air, a further fluid can be applied to the item to clean it, with this second fluid containing components to regenerate a coating of the item or similar, for example. It goes without saying that more than two different fluids can be blended in the cleaning fluid.

Usually the cleaning fluid is applied to the item using overpressure. Thus, the cleaning fluid is pressed through the item that is to be cleaned and the resulting pressure waves are used for cleaning. Alternatively or to complement this, it is of course possible to have a process design where the cleaning fluid is sucked through the item in order to clean the item.

In order to loosen and flush out contamination on and in the item in a particularly efficient manner, a provision may be made for the cleaning fluid to be applied to the item using pulsed changing pressure, for example with a pulse frequency ranging from 0.01 Hz to 500 Hz, preferably ranging from 1 Hz to 100 Hz.

A provision may be made for a fluid flow which is applied to the item to be pulsed, that is to say pressure that is changing at a high frequency in terms of time is applied to the cleaning fluid that is fed to the item. Thus, the cleaning fluid may be fed to the item with varying pressure and/or varying volume flow. Here, a provision may be made for pulsation to take place in a supersonic range, so that pressure waves are led through the item, which loosen a load of the item, in particular the contaminants loaded on a filter, from cells and flush these out of the item via the cleaning fluid that is running in the opposite direction of exhaust-gas flow. Preferably, the fluid is applied in such a way that pressure waves are generated in the item which are reflected on and/or in the item, so that an overlap and reflection of pressure waves lead to an increased cleaning effect and an improved quality of the items.

It has been proven that applying the cleaning fluid to the item at supersonic speeds enables contaminants to be loosened particularly well. It may be sufficient for the cleaning fluid to exceed supersonic speed at least locally and for a limited period of time. For air at a temperature of 20^°C, this speed is approximately 343 m/s.

In addition, a provision may be made for the cleaning fluid to be heated or cooled to a defined temperature before the cleaning fluid is applied to the item. This allows defined chemical reactions which may contribute to the thermal cleaning of the item to be triggered, for example. Furthermore, this can cause physical reactions such as the drying of moisture or liquid in the item as well as the opening up of tears, in order to better see damage through wider tears. In particular, the cleaning fluid can be heated or cooled to a temperature of 100^°C to 900^°C in order to also be able to thermally clean the item and/or dry the item whilst the fluid is flowing through the item.

In order to run the cleaning fluid into the housing a pipe or similar which is connected to a pressurised chamber can be connected to the gas outlet of the housing so that the cleaning fluid is applied to the entire area of the gas outlet.

In order to clean specific individual parts of the item which is located in the housing, a provision may be made for the cleaning fluid to be applied via a probe which is inserted into the gas outlet. In this case, the cleaning fluid only runs from the probe when it is inside the housing, usually flowing in the direction of an end face of the item. A provision may be made for cleaning using the probe to be performed both via the gas inlet and the gas outlet in order to clean different end faces of the item or the end faces of different items. Accordingly, applying cleaning fluid in the direction of exhaust-gas flow might be appropriate, this is usually done for a catalytic converter that is located upstream in the direction of exhaust-gas flow. An end face of a filter that is located downstream in direction of exhaust-gas flow is usually cleaned using a cleaning fluid which is applied via a probe in the opposite direction of exhaust-gas flow.

For especially efficient, targeted cleaning of individual areas of the item it is advantageous if the probe has at least one nozzle, preferably several nozzles, in order to apply the cleaning fluid to individual areas of the item in a targeted manner. These nozzles can for example be mounted on one end of the probe and be freely pivoted and rotating respectively. This can be done using a particular electric drive for a nozzle outlet, for example. In principle, the nozzles can be of any desired design. Preferably, the nozzles used to apply the cleaning fluid are designed to provide different speeds, particularly supersonic speed. It is beneficial if the angle of the jet of cleaning fluid emitted from the nozzles is between 0° and 45°, preferably between 10° and 20° in order to flush out contaminants particularly effectively.

Alternatively or to complement this, the cleaning fluid can also be applied with peristaltic movements, particularly using a peristaltic robot which is inserted into the housing via the gas outlet. The peristaltic robot can then be moved to various coordinate positions in order to optimally clean a surface.

The fluid is usually designed as cleaning and/or testing fluid. To this fluid, in particular to a gaseous fluid, a further substance may be added, which can change the state of the cleaning and/or testing fluid. Thereby, an increase in energy can be caused by an exothermic reaction, for example, in order to thus utilise thermic effects in cleaning, drying and chemical treatment. Furthermore, a pressure wave can thereby be created which triggers an energy impulse that can be utilised for the cleaning and testing effect. Such a change of state can be made cyclically, in particular in pulses, or continuously.

Since the housing can be designed in the most different shapes depending on the car manufacturer, it is beneficial for the probe to be designed so that it is bendable and can rotate. This then means that even if there are bends in the housing between the item and the gas outlet, the probe can pass them in order to clean the item in a targeted manner.

A particularly efficient process can be achieved if a quality of the item is assessed during cleaning or at defined time intervals. Here, a quality of the item may be defined by assessing quality characteristics such as the particle catching rate, catalytic reactivity, gas storage capacity in the item or the loss of pressure via the item, for example. It goes without saying that it is also possible to measure several types of the quality and several of the above-mentioned quality characteristics. By testing the items in parallel to or after the cleaning process, particularly in a closed- loop process, it can be determined at what point the item has been sufficiently cleaned, so that further cleaning or quality improvement is not necessary and the process can be stopped. Should the item be damaged and cleaning not lead to an improvement in quality, this can also be determined through assessing the quality. In this case, too, cleaning can be stopped if no further improvement in quality is achievable. Preferably, the item is alternatingly tested and cleaned in order to be able to stop the cleaning process once a defined state of the item has been achieved and/or no further improvement in quality can be achieved or no further improvement in quality is measured.

For the quality of the item to be assessed, a provision may be made for a testing fluid to be led through the item in the direction of exhaust-gas flow or in the opposite direction of exhaust-gas flow and the quality of the item is then assessed looking at the difference in pressure between the pressure of the testing fluid at a point upstream of the item and the pressure of the testing fluid at a point downstream of the item. Since a loss of pressure through the item increases with increasing levels of contamination, this method allows for a quality of the item to already be assessed reliably during the cleaning process. This can be done independently of the cleaning of the item or simultaneously with the cleaning.

Alternatively or to complement this, a provision may be made for a quality of the item to be assessed by moving a testing fluid with a defined chemical composition through the item and a quality of the item is then assessed by looking at the chemical components of the testing fluid at a point downstream of the item. To this end, a testing fluid with a composition that corresponds to an exhaust gas which is applied to the item during normal operation can be chosen, for example, in order to determine the exhaust data that are achievable using the item in real operation in a vehicle. In this case, the testing fluid, which is usually gaseous and dry in order to prevent damage to the item, may contain propane gas, carbon monoxide, nitrogen monoxide, ammonia or similar. Then, a reduced or oxidised component of the testing gas can be measured at a point downstream from the item, in order to draw conclusions regarding the catalytic reactivity of the item or the storage performance of the item with regard to one or more gas components. Usually the testing fluid is supplied through the gas inlet and leaves through the gas outlet after it has passed through the item, so that the testing fluid passes through the item in the direction of exhaust-gas flow. However, it is also possible to apply a testing fluid, which is usually a testing gas, to the item in the opposite direction to that of exhaust-gas flow. In this case the relevant sensors need to be placed at the gas inlet of course, in order to assess a quality of the item by looking at chemical reactions and time-related effects.

In order to assess the particle catching rate or particle penetration of the item and thus to record a further type of the quality, it may be beneficial if one quality of the item is assessed by moving a testing fluid with a defined particle load through the item and a quality of the item is then assessed by looking at the particle load, in particular the particle mass or number of particles, of the testing gas at a point downstream from the item and/or the degree of blackening of a filter. A quality is then determined from a difference between the particle load of the testing gas before and after passing through the item. A defined number of particles within a defined volume or within a defined volume flow of the testing fluid can be considered to be a defined particle load. Usually, this also includes the definition of the particle size, which is within defined limits.

With state-of-the-art exhaust-gas-treatment tracts and exhaust-gas-treatment systems, they are often designed so that the exhaust gas flows in series through at least one catalytic converter, or at least one particulate filter, both to filter particles from the exhaust gas and to reduce nitrogen oxides as well as to oxidise

hydrocarbons and carbon monoxides respectively. A filter and a catalytic converter are often placed in a single housing. It has been shown that cleaning and/or testing of such an exhaust after-treatment system can be carried out in a particularly efficient manner if the fluid, which may be designed as a cleaning fluid and/or testing fluid, is fed into the housing via the gas outlet and flows in series through the at least two gas-permeable items suitable for use in the treatment of an exhaust gas arranged in this housing. Thus, the fluid usually enters the housing at the gas outlet, subsequently flowing through the item that is downstream in the direction of exhaust- gas flow in normal operation and then through the item that is upstream in the direction of exhaust-gas flow in normal operation and after that the fluid leaves the housing at the gas inlet. However, even with several items arranged in the housing, the fluid can, of course, also flow in the same direction as that of exhaust-gas flow. Thus, the preferred provision is for the at least two gas-permeable items suitable for the treatment of an exhaust gas in a motor vehicle to be arranged in the housing in such a way that the fluid flows through the items in series. Usually the items are spaced so that there is a free space between the items.

It has been shown that items which are arranged in the housing in series can be cleaned particularly effectively if the fluid is applied under high pressure, in particular at supersonic speed, and preferably with the angle of the jet ranging from 0° to 45°, ideally from 10° to 20°. To complement this or alternatively, the fluid can also be applied at high speed and/or with a state showing a high gradient of a state, for example pressure over time. The jet or a change of state, such as a pressure wave, then at least partially remains even after passing through a first item, so that cleaning of the downstream item is possible using a kinetic energy of the jet or with a changing direction of flow of the fluid, in particular of the cleaning fluid, or with changing pressure waves.

It may be provided that a first item is designed as a catalytic converter and a second item located downstream in the direction of exhaust-gas flow in normal operation is designed as a particulate filter or as a catalytically coated filter.

According to the invention the further task is achieved by a device of the type as described at the beginning which has two lines that can be connected to the gas inlet of the housing at one end, and the gas outlet of the housing at the other and that is designed in such a way that when a line is connected to the gas inlet of a housing and the further line to the gas outlet of this housing, a fluid can be fed through the housing using this device in order to test and/or clean the item located in the housing. Preferably, the device is designed to perform a process according to the invention. Usually, the lines can be airtightly connected to the gas inlet and the gas outlet, so that a fluid that is fed into the housing via the lines is mostly fed through the item and does not leak from the housing without passing through the item.

It is beneficial if the device is designed in such a way that it can feed a fluid which is designed as a cleaning fluid into the gas outlet and receive the contaminated cleaning fluid which is leaving from the gas inlet of the housing that is connected to the device. Usually, the device is designed to create an airtight connection of a line - that is connected to a compressor and/or a device for generating a velocity, pressure and/or temperature in the cleaning fluid and/or a space, in which overpressure can be generated using the device - with a gas outlet of the housing in order to feed fluid into the housing without loss. If the cleaning fluid is applied via a probe that is inserted into the housing, an airtight connection between the line and the gas outlet is not necessarily required, however, it is still preferred to have a generally airtight connection.

Usually, the contaminated cleaning fluid is filtered after cleaning the item that is to be cleaned, and dirt as well as pollutants are separated and collected.

Furthermore, the device may be designed to apply fluid which is designed as a testing gas to the gas inlet or the gas outlet as well as to analyse the testing gas which has passed through the item in the direction or in the opposite direction to that in which an exhaust gas passes through the item in a motor vehicle in normal operation. Usually, the relevant lines can also be airtightly connected to the gas inlet and the gas outlet.

It is advantageous, if the device has at least one sensor, preferably several sensors, with which the chemical composition of a fluid entering and leaving the housing and/or a pressure and/or a particle load, in particular a particle mass, a number of particles, a size distribution of particles, and/or a change to the spectrum of a radiating medium can be measured in order to assess a quality of the item.

The process is preferably preformed fully automatically. Therefore, it is beneficial if the device for the automated assessment of the quality of the item is designed based on measured values.

Further features, advantages and effects of the invention can be seen in the design example shown below. In the drawings which are referred to: Fig. 1 shows a housing with two items suitable for exhaust-gas treatment in a motor vehicle;

Fig. 2 shows a section of a further housing with two items suitable for exhaust-gas treatment;

Fig. 3 shows a device according to the invention;

Fig. 4 shows a pressure gradient that is achievable using a device according to the invention;

Fig. 5 shows a further device according to the invention;

Fig. 6 shows a further device according to the invention;

Fig. 7 shows a detail of a device according to the invention;

Fig. 8 shows two items during cleaning in a process according to the invention;

Fig. 9 shows a housing with three items suitable for exhaust-gas treatment in a motor vehicle in a schematic diagram.

Fig. 1 shows a housing (1 ), in which the usual two items suitable for exhaust-gas treatment in a motor vehicle are arranged and through which exhaust gas flows during normal operation of a motor vehicle with a direction of flow (6). Flere, a first item takes the form of a catalytic converter (2), usually a diesel oxidation catalyst. A second item, which is arranged downstream from the catalytic converter (2) in the direction of exhaust-gas flow (6), takes the form of a filter (3), usually a ceramic, coated particulate filter. The catalytic converter (2) and the filter (3) are firmly secured in housing (1 ) so that it would only be possible to clean these items outside of the housing (1 ) by destroying housing (1 ). Using the process according to the invention, it is possible to clean these items without destroying the housing (1 ), namely by feeding a cleaning fluid into the housing (1 ) via the gas outlet (5) of housing (1 ), whereupon the cleaning fluid passes through the items in the opposite direction to that of the exhaust-gas flow (6), in a direction of cleaning-fluid flow (8), whereupon the cleaning fluid flows out of the housing (1 ) via the gas inlet (4).

The cleaning fluid can consist of one or more components. A medium can also be included in the cleaning fluid, which causes an increase in energy in the form of a pressure wave or an increase in temperature as the result of a chemical reaction. Fig. 2 shows a further housing (1 ) with items suitable for exhaust-gas treatment arranged within it. This housing (1 ) takes the form of a multiple-pass arrangement, where along two possible flow paths (7) of an exhaust gas, provision has been made for catalytic converters (2) and filters (3), which operate in series in each flow path (7). Filters (3) and catalytic converters (2) arranged in such a housing (1 ) can also be cleaned using a process according to the invention without having to disassemble the items from the housing (1 ). Flere, a cleaning fluid can be fed into the housing (1 ) via the gas outlet (5), which then flows through the items and cleans them in the process, whereupon the cleaning fluid, which is usually loaded with ash, then flows out of the housing via the gas inlet (4).

Fig. 3 shows a diagram of a device for cleaning an item arranged in a housing (1 ) according to the invention, including a housing (1 ) with items to be cleaned

connected to the device. As is apparent, the device comprises a compressor (9) for compressing the supplied air, which is then fed into an air reservoir (10). In the air reservoir (10), the air is stored under overpressure in order to continually supply the process. Flere, the air reservoir (10) is provided with a heater (11 ), in order to allow the air to be brought to the desired temperature as needed. Thus, thermal cleaning of the items can also be achieved in a simple manner.

An air filter (12) is arranged downstream of the air reservoir (10) in order to filter contaminants (21 ) out of the air before the air is fed into the housing (1 ) to clean the items. A drying system (13) is positioned downstream of the air filter (12), in order to remove any moisture from the air, so that any damage to the coatings of the items can be easily prevented.

A secondary fluid supply (15) is provided, through which a secondary fluid can be fed, in order to improve the cleaning or testing effect of the fluid being fed into the housing (1 ), for example. The feed of the secondary fluid can be controlled using a magnetic valve (14). Flere, the cleaning fluid is thereby formed of a mixture of air and the secondary fluid, however the cleaning fluid can, of course, be comprised solely of air or another fluid, in particular a gas. A further main-line magnetic valve (16) is provided to control the flow of the cleaning fluid. Using the main-line magnetic valve (16), the cleaning fluid can also be applied to the gas outlet (5) of the housing (1 ) in a pulsing manner in order to create targeted pressure waves in the housing (1 ).

A line from the device is detachable and is airtightly connected to the gas outlet (5) of the housing (1 ) so that the cleaning fluid does not escape into the surrounding area.

Once the cleaning fluid enters the housing (1 ) via the gas outlet (5), the cleaning fluid then passes through the filter (3), whereupon the cleaning fluid passes the catalytic converter (2) in the housing (1 ), whereupon the cleaning fluid flows out of the housing (1 ) via the gas inlet (4).

The contaminated fluid or rather cleaning fluid then flows back into the device via a line (17) that is detachable and is airtightly connected to the gas inlet (4) of the housing (1 ), whereupon the contaminated cleaning fluid is guided into an exhaust-air duct (18) using an extraction fan (20). The cleaning fluid is guided over an exhaust- air filtration system (19) in order to clean it so that the decontaminated cleaning fluid can flow out of the device or be reused for cleaning. For cleaning the cleaning fluid, provision may be made in particular for chemical washers, filtration systems or activated carbon or flares for the flame cleaning of harmful substances.

Contaminants (21 ) carried out of the items and collected in the exhaust-air filtration system (19) can then be disposed of. As is apparent, the cleaning fluid used to carry out the process is fed through the housing (1 ) in the opposite direction to that of the exhaust-gas flow (6).

Due to the pulsing in the cleaning fluid created using the main-line magnetic valve (16), which can result in supersonic speeds in the cleaning fluid, pressure waves are guided into the exhaust system, through which the load on the filter is loosened from the cells in the filter (3) and can be carried away by the cleaning fluid flowing in the opposite direction to exhaust-gas flow (6).

The cleaning fluid can also be designed for use in regenerating the coatings of the filter (3) or the catalytic converter (2), in order to improve the catalytic effect of the exhaust-gas components and/or the storage capacity for ammonia, by removing the mechanical covers of the catalytic hubs and allowing contamination caused by inorganic compounds such as sulphur or phosphor to be undone. In addition, inner pores can be opened so that the inner catalytic surfaces are enlarged. Using a heated cleaning fluid also allows the products of reactions and polymers of Ad-Blue to be removed from the surfaces of the items suitable for exhaust-gas treatment. Furthermore, metallic components of the housing (1 ) can also be internally freed of rust and oily deposits.

Fig. 4 shows a pressure gradient (22) of the cleaning fluid at gas outlet (5). As can be seen, the pressure gradient (22) has several pulses or rather changes from a lower to a higher level of pressure and the change happens very quickly so that steep sides are achieved. Thus, supersonic shocks can be achieved in the cleaning fluid in order to clean the items particularly effectively. In particular, fast changes in the state of the cleaning fluid or the testing fluid can be achieved to create chemical and physical effects for the improvement of the level of quality of the component to be cleaned.

Fig. 5 shows a diagram of a further device according to the invention which is designed for the testing of an item that is arranged in the exhaust gas tract of a motor vehicle. To this end, using a compressor (23) that is usually controlled, a fluid that is designed as a testing fluid is fed with a defined overpressure via a testing-fluid filter (24), a drying device (13) and a line (17) that is designed as a testing-fluid supply line (25) which is connected airtightly with the gas inlet (4), via the gas inlet (4) into the housing (1 ) and through the one or more items to be tested. The testing fluid can have a defined chemical composition, a defined pressure and/or a defined particle load, for example. As can be seen, several secondary lines (29) are connected to the testing-fluid supply line (25) which are connected via magnetic valves (14) to supply containers (27) which contain additional media (26) used for testing. Depending on the type of quality to be assessed in the one or more items, several different additional media (26) can thus be added to the testing fluid in order to assess a chemical reaction of the items to one or more of the additional media (26), for example. The additional media (26) can be solid, liquid or gaseous and be intended for cooling, heating or triggering chemical or physical reactions in the item or rather the exhaust-gas system.

The testing fluid then flows through the items suitable for exhaust-gas treatment in the housing (1 ) in the direction of the exhaust-gas flow (6), the direction in which exhaust gas flows through the housing (1 ) during normal operation, and the testing fluid subsequently flows out from the housing (1 ) at the gas outlet (5). Using sensors (31 ) that are located at the gas outlet (5) or rather connected to the outlet, chemical components in the testing fluid, a pressure as well as a particle load can be measured in order to assess a quality of the item. To this end, provision can be made, as depicted, for a further line (17) that is designed as a testing-fluid discharge line (30) which is airtightly connected with the gas outlet (5) and to which

corresponding sensors (31 ) for the quality assessment of the item are connected. In order to discharge the testing fluid from the housing (1 ), provision is made here for an exhaust fan in the testing-fluid discharge line (30). All of the aggregates and sensors (31 ) are usually connected to a control unit (28) in order to carry out the process in a fully-automated manner and assess a quality of the items or rather be able to classify them automatically. However, manual or partly-automated operation is of course also possible. Using this device, a statement can be made on a loss of pressure via the exhaust-gas after-treatment system, which is arranged in the housing (1 ), on a catalytic reactivity that can be achieved with this, and on mechanical damage to the items arranged in the housing (1 ). To this end, relevant sensors (31 ) such as pressure sensors and gas sensors as well as possibly optical sensors (31 ) and/or particle sensors are arranged in the testing-fluid supply line (25) and/or the testing-fluid discharge line (30) or rather connected to them.

The device shown in fig. 5 can of course be combined with the device shown in fig. 3, so that it is possible to automatically switch between cleaning and testing the device or for testing and cleaning to also be carried out simultaneously. To this end, the testing fluid can also be moved through the housing (1 ) in the opposite direction to that of exhaust-gas flow (6). The cleaning process can then be ended in an automated manner based on a success of the cleaning or rather an improvement in quality that has been achieved. This alternating cleaning and testing can be used for process control in the form of a closed control loop in order to achieve a specific result or rather a desired level of cleaning as a result of the cleaning. Cleaning is usually only cancelled when one or more cancellation criteria have been met and is thus independent of time. If required, fixed process times can be set and different cleaning results can be achieved within certain operational limits.

Fig. 6 shows a device for the execution of a process according to the invention in an overview diagram of a compact system for the quality improvement of exhaust gas components. The device has an overpressure unit (32) which contains the

compressor (9) and the air reservoir (10) as well as a magnetic valve (14). Via a line (17), the overpressure unit (32) is airtightly connected to the gas outlet (5) of the housing (1 ) which has been removed from the exhaust tract of a motor vehicle or other machine with an internal combustion engine. A filter (3) and a catalytic converter (2) are arranged in the housing (1 ). The device is also designed to have a negative-pressure unit (33) which contains the extraction fan (20) and the exhaust- air filtration system (19). The negative-pressure unit (33) is connected airtightly to the gas inlet (4) via a further line (17) in order to clean the contaminated cleaning fluid leaving the housing (1 ) and to collect contaminants (21 ) so that they can be disposed of. As can be seen, the device has a mobile design so that it can be used very easily in workshops for cleaning exhaust-gas treatment systems, for example. This makes it possible to achieve a combination of overpressure before the housing (1 ) and negative pressure after the housing (1 ), which enables the contaminants (21 ) in the items that are arranged in the housing (1 ) to be removed very effectively. It goes without saying that the lines (17) can also be used as testing-fluid supply lines (25) and testing-fluid discharge lines (30), in order to assess the items that are arranged in the housing (1 ).

Fig. 7 shows a probe for carrying out a process according to the invention, which can be inserted into the housing (1 ) via the gas outlet (5) in order to clean individual areas of the item in a targeted manner. Using the probe (36), which is usually connected to the overpressure unit (32) or rather a compressor (9) via a line (17) and a magnetic valve that is not shown, the cleaning fluid can be applied to individual areas of the item at a small jet angle (35) of between 1 ° and 45°, preferably between 10° and 15° and at supersonic speed as well as pulsed if needed, in order to clean these areas in a targeted manner. The nozzles (34) are usually pivoting.

Furthermore, a camera or similar can be provided, in order to easily identify heavily contaminated areas and to clean these in a targeted manner using the probe (36). It goes without saying that the probe (36) can be moved in various spatial directions during the process. In particular, the probe (36) can usually be moved translationally in three spatial directions perpendicular to one another and be rotated around three spatial axes which are perpendicular to one another.

Fig. 8 shows a diagram of the cleaning of a catalytic converter (2) and a filter (3) which is designed as a particulate filter in a process according to the invention, using a nozzle (34) which can be mounted on a probe (36) according to fig. 7 with the cleaning fluid being applied to channels (38) of the particulate filter using a jet (37) with a small jet angle (35). As can be seen, the shape of the jet (37) is still clearly recognisable after it has passed the filter (3) or rather the channels (38), so that the jet (37) or rather the kinetic energy of it and the cleaning fluid, usually air, can even be applied to the catalytic converter (2) which can thus be cleaned particularly effectively. The catalytic converter (2) and the filter (3) are arranged in a housing (1 ) which is not shown here and the cleaning fluid is flowing through them in series so that both items can be cleaned at the same time.

Fig. 9 shows a diagram of a further housing (1 ), including items suitable for exhaust- gas treatment, with which the process according to the invention can be used. As can be seen, this housing (1 ) also has a gas inlet (4) and a gas outlet (5) via which an exhaust gas usually flows through the housing (1 ) during normal operation. In the housing (1 ), a catalytic converter (2) and two downstream particulate filters are arranged, so that during operation, exhaust gas flows into the housing (1 ) via a gas inlet (4). It subsequently flows along a flow path (7) in the direction of the exhaust- gas flow (6) and first passes the catalytic converter (2). The exhaust gas then passes in series through the two filters (3) before it flows out from the housing (1 ) via the gas outlet (5). There is an additional opening (39) between the catalytic converter (2) and the particulate filters. This can be used to supply substances (40) to the housing (1 ) for selective catalytic reactions during operation, in particular urea or rather so-called AdBlue. Since exhaust gas could also be supplied to the housing (1 ) via this opening (39) in order to clean it, this opening (39) is also considered to be a gas inlet (4) or gas outlet (5) respectively in accordance with this invention.

When implementing the process according to the invention, the additional opening (39) can thus be used for both supplying cleaning and/or testing fluid and

discharging a cleaning and/or testing fluid that has been supplied to the housing (1 ) via the gas inlet (4) or the gas outlet (5). However, provision may also be made so that the housing (1 ) as shown in fig. 9 is cleaned and/or tested by first closing the additional opening (39) and then supplying a cleaning and/or testing fluid to the housing (1 ) via the gas outlet (5) which subsequently first passes through the two filters (3) in series in the opposite direction to that of exhaust-gas flow (6) and then through the catalytic converter (2), after which the cleaning and/or testing fluid is discharged from the housing (1 ) at the gas inlet (4). Using a process and a device according to the invention, items suitable for exhaust- gas treatment such as filters (3) or catalytic converters (2) can be cleaned without having to be removed from a housing (1 ). This means a corresponding process can be executed much more efficiently than any process according to the currently best- available technologies, which requires the items to be removed from the housing (1 ).

Claims

Patent claims

1. A process for cleaning and/or testing a gas-permeable item suitable for use in the treatment of an exhaust gas from an internal combustion engine, in particular a filter (3) or catalytic converter (2) of a motor vehicle, which for said exhaust-gas treatment is arranged in a housing (1 ) with a gas inlet (4) and a gas outlet (5) in such a way that an exhaust gas fed into the housing (1 ) via the gas inlet (4) at least in part passes through the item suitable for exhaust-gas treatment before the exhaust gas leaves the housing (1 ) via the gas outlet (5), characterised in that a line (17) from a device is connected to the gas outlet (5) and a further line (17) from the device is connected to the gas inlet (4), whereupon using the device a fluid is fed through the item via the lines (17) in order to test and/or clean the item.

2. A process in accordance with claim 1 , characterised in that the item is cleaned using a cleaning fluid, which is introduced into the housing (1 ) via the gas outlet (5), whereupon the cleaning fluid passes through the item in order to clean the item, whereupon the cleaning fluid is discharged from the housing (1 ) via the gas inlet (4) with the cleaning fluid preferably being dried before it is applied to the item.

3. A process in accordance with claim 2, characterised in that the cleaning fluid contains a first fluid and a second fluid, with the second fluid preferably being added using a magnetic valve (14) before the cleaning fluid is led through the item.

4. A process in accordance with claim 2 or 3, characterised in that the cleaning fluid is applied to the item under a pulsed, alternating pressure.

5. A process in accordance with any of the claims 2 to 4, characterised in that the cleaning fluid is applied to the item at supersonic speed.

6. A process in accordance with any of the claims 2 to 5, characterised in that the cleaning fluid is applied using a probe (36), which is preferably designed so that it is bendable and/or able to rotate, inserted into the gas outlet (5).

7. A process in accordance with claim 6, characterised in that the probe (36) has at least one nozzle, preferably several nozzles (34), in order to apply the cleaning fluid to individual areas of the item in a targeted manner.

8. A process in accordance with any of the claims 1 to 7, characterised in that a quality of the item is assessed by moving a testing fluid with a defined chemical composition through the item, and a quality of the item is then assessed by looking at chemical components of the testing fluid at a point downstream of the item.

9. A process in accordance with any of the claims 1 to 8, characterised in that at least two gas-permeable items suitable for the treatment of an exhaust gas in a motor vehicle are arranged in the housing (1 ) with the fluid flowing through the items in series.

10. A process in accordance with claim 9, characterised in that a first item is designed as a catalytic converter (2) and a second item located downstream in the direction of exhaust-gas flow (6) in normal operation is designed as a particulate filter.

11. A process in accordance with any of the claims 1 to 10, characterised in that prior to the cleaning and/or testing, the housing (1 ) is removed from the exhaust tract of a machine with an internal combustion engine, in particular of a motor vehicle, in which the housing (1 ) was used for exhaust-gas treatment prior to cleaning and/or testing.

12. A process in accordance with any of the claims 1 to 10, characterised in that during the cleaning and/or testing, the housing (1 ) is arranged in an exhaust tract of a machine with an internal combustion engine, in particular of a motor vehicle, in which the housing (1 ) was used for exhaust-gas treatment prior to cleaning and/or testing.

13. A device for cleaning and/or testing a gas-permeable item suitable for use in the treatment of exhaust gas from an internal combustion engine, in particular a filter (3) or catalytic converter (2) in a motor vehicle, which for said exhaust-gas treatment is arranged in a housing (1 ) with a gas inlet (4) and a gas outlet (5) in such a way that exhaust gas fed into the housing (1 ) via the gas inlet (4) at least in part passes the item before the exhaust gas leaves the housing (1 ) via the gas outlet (5), characterised in that the device has two lines (17) that can be connected to the gas inlet (4) of the housing (1 ) at one end, and the gas outlet (5) of the housing (1 ) at the other and that is designed in such a way that when a line (17) is connected to the gas inlet (4) of a housing (1 ) and the further line (17) to the gas outlet (5) of this housing (1 ), a fluid can be moved through the housing (1 ) using this device in order to test and/or clean the item arranged in the housing (1 ) with the device being specifically designed for carrying out a process in accordance with any of the claims 1 to 12.

14. A device in accordance with claim 13, characterised in that the device is designed to feed a fluid which is designed as a cleaning fluid into the gas outlet (5) and receive the contaminated cleaning fluid which is leaving from the gas inlet (4).

15. A device in accordance with claim 13 or 14, characterised in that the device for the automated assessment of the quality of the item is designed based on measured values.