DE102017211822A1 - Method for determining a condition of an exhaust gas treatment element, device for a motor vehicle and system for exhaust gas treatment for a motor vehicle - Google Patents

Abstract

A method for determining a condition of an exhaust gas treatment element (100) for a motor vehicle comprises: - emitting microwaves (112) into a housing (102) of a further exhaust gas treatment element (101) located downstream of the exhaust gas treatment element (100), - receiving Microwaves having at least one property in response to the emission, - determining the state of the exhaust treatment element (100) in dependence on the at least one property.

Description

The application relates to a method for determining a state of an exhaust gas treatment element for a motor vehicle, in particular a method for determining a state of a particulate filter and / or catalyst. The application relates wieterhin a device that is designed to perform a corresponding method. The application also relates to a system for exhaust gas treatment for a motor vehicle.

Motor vehicles with internal combustion engines, such as petrol or diesel internal combustion engine or gas engine need to comply with the statutory emission limits various components for exhaust treatment, especially for exhaust aftertreatment. These include, inter alia, the three-way catalyst, the diesel oxidation catalyst, the nitrogen oxide storage catalyst, the SCR catalyst (Selective Catalytic Reduction), the diesel and Ottopartikelfilter and other elements. The individual elements can also be combined, for example a particle filter with SCR coating (SDPF).

It is desirable to provide a method for determining a condition of an exhaust gas treatment element for a motor vehicle, which enables a reliable determination. Furthermore, it is desirable to provide a device that allows reliable detection. In addition, it is desirable to provide a system for exhaust gas treatment for a motor vehicle, which enables a reliable determination of a condition of an exhaust gas treatment element.

The invention relates, in accordance with at least one embodiment, to a method for determining a condition of an exhaust gas treatment element for a motor vehicle and to a corresponding device, which is designed to carry out the method.

In accordance with at least one embodiment, microwaves are emitted into a housing of a further exhaust gas treatment element. The further exhaust gas treatment element is arranged downstream of the exhaust gas treatment element. Starting from the internal combustion engine, the exhaust gas initially flows through the exhaust-gas treatment element during operation and subsequently through the further exhaust-gas treatment element and in turn subsequently, for example, to an exhaust.

The microwaves are received with at least one property in response to the broadcast. A state of the exhaust gas treatment element is determined as a function of the at least one property.

The exhaust gas treatment element is for example a filter of an exhaust aftertreatment system of the motor vehicle. The filter is for example a particle filter, in particular a soot particle filter.

Alternatively or additionally, the exhaust gas treatment element is in particular a catalyst of an exhaust aftertreatment system of the motor vehicle.

According to further embodiments, the exhaust gas treatment element is alternatively or additionally a further component of the exhaust gas treatment system or exhaust gas after-treatment system of the motor vehicle, for example a control flap or another element.

The further exhaust gas treatment element is according to at least one embodiment a filter, for example a particle filter, in particular a soot particle filter.

Alternatively or additionally, the further exhaust gas treatment element is a catalyst. The further exhaust gas treatment element can also be another component of the exhaust gas aftertreatment system, which can be checked in particular by means of a microwave measuring system.

By means of the method it is possible to determine the condition of the exhaust gas treatment element, even if the exhaust gas treatment element itself is not directly equipped with a microwave measuring system.

According to the application, an electromagnetic wave in the microwave range is coupled into the housing by means of one or more high-frequency antennas. The metallic housing (Canning) represents an electrical cavity resonator. In response to the transmitted wave, a spectrum is recorded either in reflection or in transmission. The properties of the spectrum change with a change in the dielectric constant in the housing. Thus, it is also possible to determine damage and / or changes of an exhaust gas treatment element without contact during operation. Alternatively or in addition to the change in the dielectric constant, a change in the conductivity and / or losses is utilized as a measuring effect.

In a fully functional exhaust treatment element, the exhaust treatment element has no or no significant influences on the dielectric constant and / or the conductivity and / or losses of the further exhaust gas treatment element. Consequently, the at least one property of the microwaves is only from Operating conditions of the further exhaust treatment element influenced.

In the event of a faulty state of the exhaust gas treatment element, particles pass from the exhaust gas treatment element into the further exhaust gas treatment element arranged downstream. These particles have effects on the dielectric constant and / or the conductivity and / or losses of the further exhaust gas treatment element and thus on the properties of the spectrum of the microwave propagation. In the received microwaves these properties can be detected.

Thus, it is possible to close by means of the microwave measuring system of the further exhaust gas treatment element on the state of the upstream exhaust gas treatment element.

The particles that pass from the exhaust gas treatment element into the further exhaust gas treatment element may be soot or ash particles or other exhaust gas components. The particles may also be parts of the exhaust gas treatment element itself, which are broken off, for example, by the exhaust gas treatment element. For example, a broken splitter of the control flap enters the further exhaust gas treatment element and changes the dielectric constant there. The change in the dielectric constant and / or the conductivity and / or the losses has an effect on the propagation of the microwaves in the further exhaust gas treatment element.

Thus, it is possible by means of the method to determine even small defects in the exhaust gas treatment element, which can not be reliably determined conventionally, since they cause, for example, no detectable change in the back pressure behavior.

In accordance with at least one embodiment, a degree of damage is determined as the state of the exhaust-gas treatment element. Depending on how quickly the property of the received microwaves changes, it is possible, for example, to conclude on the degree of damage and / or the type of damage. For example, if there is little damage, the property changes only slowly. In a larger crack, for example in a filter, the property changes very quickly. If, for example, a part of the filter breaks off, an abrupt change in the property is initially detectable and subsequently a further increase, since, for example, soot particles are deposited in the further exhaust gas treatment element.

In accordance with at least one embodiment, the characteristic of the received microwaves is at least one of: amplitude, resonance frequency, quality, phase, transit time, gradient and jump change. Due to the change in the dielectric constant and / or the conductivity and / or the losses, at least one of the properties of the received microwaves changes. In the case of a fully functional exhaust gas treatment element, the received microwaves have, in particular, a different amplitude and / or a different resonance frequency and / or a different quality and / or a different phase and / or a different transit time and / or a different gradient and / or a different jump change Compared to a faulty functional state of the upstream exhaust treatment element.

In accordance with at least one embodiment, a state of the further exhaust-gas aftertreatment element is determined as a function of the received microwaves. For example, if the further exhaust aftertreatment element is a filter or a catalyst, a loading state of the further exhaust aftertreatment element is determined in order to determine a time for a regeneration.

In accordance with at least one embodiment, an ambient condition of the further exhaust gas treatment element is determined. The condition of the exhaust treatment element is determined as a function of the determined ambient condition. The ambient condition includes, for example, a temperature at the further exhaust gas treatment element. The ambient conditions may be other influencing factors which have an effect on the propagation of the microwaves in the further exhaust gas treatment element. Changes in the property of the microwaves that take place due to the determined environmental conditions can thus be distinguished from changes that are representative of the condition of the exhaust gas treatment element.

In accordance with at least one embodiment, an operating state of the further exhaust gas treatment element is determined. The state of the exhaust gas treatment element is determined as a function of the determined operating state. For example, the operating state comprises a defined predetermined activation of the further exhaust gas treatment element. For example, an operating state of the further exhaust gas treatment element is specified in which there is no change in the property of the microwaves when the exhaust gas treatment element is fully functional. If, nevertheless, a change in the property of the microwaves is determined, it is possible to conclude that the exhaust-gas treatment element is defective.

According to one aspect of the application, a system for exhaust gas treatment for a motor vehicle according to at least one embodiment has an exhaust gas treatment element. The system includes another exhaust treatment element disposed downstream of the exhaust treatment element. The system has a microwave measuring system. The microwave measuring system is coupled to the further exhaust gas treatment element. The microwave measuring system is configured to determine a state of the exhaust gas treatment element.

In particular, it is possible to carry out a method according to the application with the system according to the application. All features and advantages explained for the method according to the application apply correspondingly also to the device and the system and vice versa.

Further advantages, features and developments emerge from the following examples explained in conjunction with the figures. Identical, equivalent or similar elements can be provided across the figures with the same reference numerals.

• 1 eine schematische Darstellung eines Systems gemäß einem Ausführungsbeispiel,
• 2 eine schematische Darstellung eines Systems gemäß einem Ausführungsbeispiel,
• 3 eine schematische Darstellung von Frequenzverläufen gemäß einem Ausführungsbeispiel,
• 4 bis 6 jeweils eine schematische Darstellung eines Signalverlaufs gemäß einem jeweiligen Ausführungsbeispiel.

Show it:

• 1 a schematic representation of a system according to an embodiment,
• 2 a schematic representation of a system according to an embodiment,
• 3 a schematic representation of frequency characteristics according to an embodiment,
• 4 to 6 each a schematic representation of a signal waveform according to a respective embodiment.

1 shows an exhaust treatment system 111 , in particular an exhaust aftertreatment system of a motor vehicle. exhaust 103 , For example, from an internal combustion engine not explicitly shown, is in the system 111 introduced. Along the flow direction of the exhaust gas 103 is first an exhaust gas treatment element 100 arranged. Downstream of the exhaust treatment element 100 is another exhaust treatment element 101 arranged. After the further exhaust treatment element leaves exhaust 104 the system 111 , The exhaust 104 is in particular a part of the exhaust gas cleaned of emissions 103 ,

The exhaust gas treatment element is for example a filter, in particular a particle filter such as a soot particle filter. The exhaust treatment element 100 is alternatively or additionally a catalyst or a combination of a catalyst and a particulate filter. The exhaust treatment element 100 is alternatively or additionally another component of the system 111 , such as a control valve, which is designed, a volumetric flow of the exhaust gas 103 through the system 111 to control. Also other components as exhaust gas treatment element 100 are possible.

The exhaust treatment element 101 For example, it is arranged as close as possible to the internal combustion engine since higher temperatures prevail there. This can favor, for example, a passive regeneration. The exhaust treatment element 101 can also be located away from the engine. Further exhaust gas treatment elements, such as, for example, three-way catalytic converter, SCR and / or NOx storage catalytic converter, are therefore arranged downstream, in particular downstream of the internal combustion engine.

The further exhaust gas treatment element 101 is also for example a filter and / or a catalyst and / or a combination of filter and catalyst. The further exhaust gas treatment element 101 has a housing 102 on. The housing 102 is in particular a metallic housing. The housing 102 forms a cavity. The housing 102 is for example a cavity resonator for microwaves 112 or a waveguide.

According to one embodiment, the exhaust treatment element 101 a particulate filter and the further exhaust gas treatment element 101 an SCR catalyst.

In the case 102 is in the illustrated embodiment, an exhaust treatment module 106 arranged, for example, a filter module or a catalyst module. For example, the exhaust treatment element becomes 100 loaded during operation with various substances, for example with NH3 in an SCR catalyst and / or soot in a particulate filter.

For example, a loading state of the further exhaust gas treatment element by means of a microwave measuring system 113 determined. The loading state can be determined well with high-frequency measurement technology, in particular with microwaves. The microwaves are for example in a range between 300 megahertz and a few 100 gigahertz. To send and receive microwaves 112 are in the embodiment shown a first transmitting and receiving device 107 and a second transmitting and receiving device 108 intended. These are, for example, each high-frequency antennas, which are coupled to a corresponding exciter, such as an oscillator. The coupling can be electrical and / or inductive respectively. The microwaves are received, for example, after transmission or reflection.

For example, the device sends 107 the microwaves 112 out. In response, the device receives 108 the microwaves passing through the module 106 are transmitted.

According to a further embodiment, only a single transmitting and receiving device 107 intended. This first sends the microwaves 112 out in the case 102 be reflected and subsequently again from the transmitting and receiving device 107 be received.

A device 110 is planned. The device 110 is for example part of an engine control of the motor vehicle. The device 110 serves to evaluate the received microwaves or to evaluate a property of the received microwaves. In addition, the device can 110 also be designed to the transmitting and receiving devices 107 . 108 head for.

The property of the received microwaves, for example an amplitude, a resonant frequency, a quality or other properties change depending on the state of the module 106 , When fully functional exhaust treatment element 100 has the exhaust gas treatment element 100 no effect on a change in the property of microwaves 112 , For example, the exhaust gas treatment element 100 a particle filter. As a result, the exhaust gas faces the exhaust treatment element 100 no significant soot anymore. Only other emissions become a further exhaust gas treatment element 101 guided. These are the other exhaust treatment element 101 , For example, a catalyst, treated. Thus, the exhaust gas 104 exempt from exhaust and soot.

2 shows the system 111 at a faulty exhaust treatment element 100 according to an embodiment. Due to an error, for example, soot gets into the further exhaust gas treatment element 101 , A deposit 105 forms in the further exhaust gas treatment element 101 , The deposit 105 is due to the fault of the exhaust treatment element 100 caused. The deposit 105 changes the dielectric constant in the housing 102 , Thus, the property of the microwaves changing from the transmitting and receiving device also changes 108 be determined. Thus, by means of the microwave measuring system 113 an error of the exhaust treatment element 100 determined. The error causes, for example, that in the exhaust 104 Soot particles are included.

The deposit 105 leads for example to a higher half-width, lower frequency, lower quality and / or lower amplitude, as well as a change in phase and duration of the wave.

Also a higher temperature at the further exhaust gas treatment element 101 leads, for example, to a thermal expansion of the housing 102 and thus to lower frequencies. But this is for example the device 110 compensated by software. Also, further measured variables can be taken into account in the evaluation of the received microwaves, for example further temperatures, a moisture level, a loading state of the further exhaust gas treatment element 101 and other components.

The microwave measuring system 113 thus serves to determine a state of the further exhaust gas treatment element 101 and simultaneously for determining a condition of the exhaust treatment element 100 , In particular, it is thus possible to determine even minor damage.

Under normal conditions, as in 1 shown, the soot accumulates in the filter 100 and the remaining pollutants are in the catalyst 101 implemented.

Does it come to a filter damage, as in 2 represented so soot is located in the exhaust gas after the filter 100 as well as deposit 105 on the catalyst 101 accumulated, for example due to a physical deposition process. Thus, the losses increase in the resonator, for example in the housing 102 who is the catalyst 106 encloses. This has an effect on the microwave signals additive to the actual signal of the catalyst state.

3 shows frequency characteristics 121 . 122 and 123 according to an embodiment. The frequency curves 121 and 122 in this case correspond, for example, to a resonance in the reflection signal in the context of the loading state of the further exhaust gas treatment element 101 For example, the frequency response shifts from the frequency response 121 to the frequency response 122 , Within a normal function of the upstream exhaust treatment element 100 However, the change in the frequency response remains within a predetermined range 120 , For calibrated systems are the limits of the range 120 known as the normal operating area. In the event that several resonances are evaluated simultaneously, individual resonances can be especially for the error monitoring of the exhaust gas treatment element 100 to offer.

In case of failure of the exhaust treatment element 100 For example, soot accumulates on the catalyst 106 , Thus, there is an unusual change in the resonance behavior to the frequency response 123 , The frequency response 123 is outside the usual workspace 120 , Thus, the frequency history 123 clearly a malfunction of the exhaust treatment element 100 assignable.

As also follows from the 4 to 6 results, a temporal behavior of the change can be included.

4 shows a change in a waveform 131 to the waveform 132 at a small error according to an embodiment.

The waveform 131 corresponds to a normal working exhaust treatment element 100 , The waveform 131 is within the workspace 130 , For a small mistake, for example a small crack in the filter 100 , is only a very small amount of soot after the filter in the exhaust. A slow accumulation on the downstream arranged catalyst 106 leads to a slow steady increase of the signal curve 132 , For example, the error occurs at the time 136 on. The fault of the exhaust treatment element 100 caused increase is additive to the actual, the state of the catalyst 106 reflected signal 131 , so the waveform 132 the usual operating window 130 leaves.

5 shows a waveform 133 in a larger error according to an embodiment. A larger crack or an open channel in the filter 100 For example, leads to a higher amount of soot after the filter. The faster accumulation in particular compared with the embodiment according to 4 leads to a faster steady signal rise of the signal 133 , The normal operating window 130 is thereby quickly abandoned.

6 shows a waveform 135 when canceling part of the filter 100 according to an embodiment. A part of the filter or another element breaks off and becomes the exhaust gas element with the exhaust gas 101 , for example to the catalyst 106 carried. For example, the broken part remains at its front as part of the deposit 105 , In addition, soot goes after the filter 100 on. Due to the additional material of the filter 100 on the catalyst 106 it comes first immediately after the error 136 to a sudden change in the signal curve 134 , Then it comes by Rußakkumulation on the catalyst 106 to a steady further increase 135 ,

Due to the different courses of the signal course 131 , the waveform 132 , the waveform 133 and the waveform 134 it is possible for an error in the exhaust treatment element 100 close, and determine the nature of the error. In this case, in particular the time profile, for example, the gradient of the signal change is taken into account. In particular, both the signal level and the gradient are taken into account for determining the state.

Changes the waveform compared to the waveform 131 stronger than actually possible and leaves the area 130 , so there is a mistake in the exhaust gas treatment element 100 in front. According to one embodiment, a state determination for the exhaust gas treatment element 100 executed when defined operating conditions for the further exhaust gas treatment element 101 available. For example, a state is defined in which no ammonia enters the SCR catalyst 101 is injected. As a result, under normal operating conditions, the dielectric constant within the housing 102 should not change, the condition of the exhaust treatment element can be changed 100 determine well. If, nevertheless, a change, in particular stronger than the predetermined range 130 takes place, this leaves unwanted accumulation of the deposit 105 shut down. This is most likely due to a fault in the exhaust treatment element 100 caused.

With the method according to the application, the device and the system is thus possible, a malfunction of any exhaust treatment element 100 to be determined by means of the microwave measuring system 113 at the downstream further exhaust treatment element 101 is arranged.

Claims (11)

A method of determining a condition of an exhaust treatment element (100) for a motor vehicle, comprising: Emitting microwaves (112) into a housing (102) of a further exhaust gas treatment element (101), which is arranged downstream of the exhaust gas treatment element (100), Receiving microwaves having at least one property in response to the emission, - Determining the state of the exhaust treatment element (100) in dependence on the at least one property. Method according to Claim 1 comprising: determining a health condition as the condition of the exhaust treatment element (100). Method according to Claim 1 or 2 comprising: determining a degree of damage as the condition of the exhaust treatment element (100). Method according to one of Claims 1 to 3 in which the property of the received microwaves is at least one of: - amplitude, - resonance frequency, - quality, - phase, - transit time, - gradient, and - jump change. Method according to one of Claims 1 to 4 comprising: determining a condition of the further exhaust aftertreatment element (101) in dependence on the received microwaves. Method according to one of Claims 1 to 5 comprising: determining an ambient condition of the further exhaust gas treatment element (101), determining the state of the exhaust gas treatment element (100) as a function of the determined ambient condition. Method according to one of Claims 1 to 6 comprising: determining an operating state of the further exhaust gas treatment element (101), determining the state of the exhaust gas treatment element (100) as a function of the determined operating state. A device for a motor vehicle for determining a condition of an exhaust gas treatment element (100), which is adapted to a method according to one of Claims 1 to 7 perform. A system for exhaust gas treatment for a motor vehicle, comprising: an exhaust gas treatment element (100), another exhaust treatment element (101) downstream of the exhaust treatment element (100), a microwave measurement system (113) coupled to the further exhaust treatment element (101) and configured to determine a state of the exhaust treatment element (100). System after Claim 9 in which the exhaust gas treatment element (100) is at least one of: filter, catalyst and control flap. System after Claim 9 or 10 in which the further exhaust gas treatment element (101) is at least one of: filter and catalyst.

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