DE8905073U1 - Electrically conductive honeycomb body - Google Patents

Description

Emitec GmbH 89 G 67 1 2 EN

D-5204 Lohmar 1

^Electrically conductive honeycomb body ~p

The present invention relates to an electrically conductive roller body, in particular as a carrier body for Abcas catalysts, made of wound, stacked or otherwise layered layers of at least partially structured high-temperature corrosion-resistant sheets, which form a plurality of channels through which a fluid can flow.

The essential features of the honeycomb bodies according to the invention are discussed below based on their advantages, including their use as catalyst carrier bodies, but this does not exclude other, comparable applications. Such honeycomb bodies can be used, for example, to heat fluids, to evaporate liquids, etc.

Based on the widely known state of the art technology in automotive catalysts, namely the regulated

Three-way catalyst, the embodiments β of the present invention are mainly concerned with the acceleration κ of the response, control and monitoring of such

: Catalyst arrangements.

So far, so-called starter catalysts, also known as pre-catalysts, have been used in many cases to reduce pollutant emissions during the cold start phase of a motor vehicle. Such starter catalysts, which are installed close to the engine ^and have metallic support structures, heat up more quickly than the bulky main catalysts, since they are closer to the engine.

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lam engine and have a smaller volume. Nevertheless, starting catalysts also require a certain amount of time to respond, since their catalytically active mass, their ceramic carrier material and the metallic support structure

5must first be heated up by the exhaust gas. In doing so, they first extract heat from the exhaust gas, which means that the main catalysts located further back also reach operating temperature more slowly*

&iacgr; 10 Various variants of V-bodies are known as metallic supporting structures, which are explained in detail in the following documents, for example:

EP-CO 049 489, EP-CO 121 174, EP-CO 121 175, EP-A-&Pgr; 245 737, EP-AO 245 738
15

In particular, so-called S-shaped honeycomb bodies and also those with U-shaped sheet metal layers are also known from these documents.

Finally, it has long been known that a metallic honeycomb body can be heated electrically. This is described, for example, in DE-PS-563 757. Other attempts to heat a catalyst body using an electrical heating element are known from OE-AS-22 30 663

25. The direct electrical heating of catalyst carrier bodies has, however, encountered great difficulties so far, since the usual metallic structures have too low an electrical resistance to be used directly as heating elements with the electrical voltages that are usual and available in motor vehicles. In DE-PS-563 757, therefore, only separate partial areas were heated, which could be designed in this way because they have a suitable resistance. In DE-AS-22 30 663, a separate heating element is used, which does not simultaneously serve as a catalyst carrier body.

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lOn the other hand, if one were to use the entire length of the wound sheet metal in spirally wound honeycomb bodies by appropriately insulating the sheet metal layers, the resistance would be too high, which would not produce sufficient current for the

5would allow the power required for heating.

The object of the present invention is therefore to modify the structure of a metallic honeycomb body with the aim of increasing its resistance within wide limits, independent of its

The aim is to be able to freely select the volume of the honeycomb body, so that in particular heating the honeycomb body with the voltage or current sources usually available in motor vehicles is possible without any problems. In addition or alternatively, it should be possible to determine the temperature of a honeycomb body by observing the temperature-dependent resistance and to use this information to enable regulation or control processes.

To solve this problem, the present invention teaches that 20the honeycomb body should be electrically divided by gaps and/or electrically insulating intermediate layers or coatings with respect to its cross-sectional area and/or its axial extent so that at least one electrical current path through the sheets with an" electrical

^•^ irr I u6I51 and Between 0.03 UHu 7 Ohm ciyibt, VGIZUySwS156 between 0.1 and 1 Ohm, in particular about 0.6 Ohm. As is explained in more detail on the drawing, the number of gaps and/or intermediate layers necessary to achieve a certain resistance depends on several parameters.

3OoThe thickness of the individual sheets, their structure, the cross-sectional area of the individual channels and the choice of material have an influence. Sheets with a thickness of about 0.03 to 0.12 mm can be used, preferably 0.03 to 0.06 mm. Common materials are steel sheets with

35chromium and aluminum components. The invention covers various variants of electrically heated catalysts.

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What they have in common is that they are separated by gaps
and/or electrically insulating intermediate layers divided
or separated from their casing pipe so that at least
an electrical current path through the catalyst carrier body

with an electrical resistance between 0.03 and 2 ohms
A resistance in this range is suitable
especially for electrical heating in conventional
12-volt systems. It must be taken into account that at high current levels, considerable losses in the supply lines j

may occur, so that the catalyst carrier body itself may only have a small voltage, for example
10 volts is present.

If a vehicle has several electrically heated
Catalysts are present, there are always different
Variants of electrical interconnection. Either
the individual bodies are designed with a high resistance
and then connected in parallel, or they have a
relatively low electrical resistance and are
connected in series accordingly. Time-dependent

Switching from parallel to series connection can be provided

provided that the electrical heating output depends on the |

Operating state should be varied. $

'■-'The commonly used high temperature temperature for solid ^

Sheets with a thickness of about 0.03 to 0.06 mm would have on the 1

entire length required for the formation of a catalyst-support- ^

body is required, one for the intended electrical I

Heating to high resistance. A catalyst carrier body at |

where all structured sheets touch or even :j

are joined together, would have too low a :

Resistance for an electric heater with 12 volts. In I

Result, therefore, a catalyst carrier body must be so |

be divided into such that, depending on its total volume, a |

Current path with a suitable combination of length and §

Conductivity is created. One possibility is the §

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!Division of the cross-section into electrically connected segments, each consisting of more than four parallel layers of sheet metal, preferably eight to twelve layers of sheet metal.

A further possibility is to divide the catalyst carrier body into axially successive layers which are electrically connected in series ^. Both possibilities can also be used in combination, as will be explained using the embodiments.

Some special features arise when integrating the electrically heatable catalyst carrier body into a jacket tube, since at least parts of the catalyst carrier body must be electrically insulated from the jacket tube. In addition, suitable insulated feedthroughs must be provided for the electrical supply lines. However, this does not cause any major problems when using jacket tubes made up of half-shells, for example. The insulation between the catalyst carrier body and the jacket tube can provide thermal and electrical insulation at the same time, which is particularly advantageous.

The invention also relates to problem solutions in some details for special applications. As explained in more detail in the drawing, it can be useful to provide connecting struts on one or both ends of a honeycomb body in order to even out the distribution of the current density in the honeycomb body. If relative expansion is to be expected between the heatable honeycomb body and its casing tube, an electrical supply line may have to be designed to be elastic so that this expansion can be compensated. Such a supply line may have to be designed for currents of 50 to 400 amperes.
35

If high axial mechanical loads are expected

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In the case of a honeycomb body, it can be important to prevent electrically insulated sheet metal layers from axially shifting by means of positive locking connections. It is well known that ceramic insulating layers cannot withstand high tensile loads.

5 a form-locking connection can help to absorb the forces that occur. In particular, if the form-locking connection has a depth that is greater than the thickness of the insulating layer, axial forces lead mainly to compressive loads on the ceramic intermediate layer in this area and not to tensile loads.

Electrically conductive catalyst carrier bodies, in particular those described so far, but also others, e.g. those produced by powder metallurgy, can, if they are at least partially

15insulated from their casing and their supports and provided with a catalytically active coating are used in the exhaust system of an internal combustion engine, are monitored by measuring their electrical resistance as a whole or in a partial area and

20monitoring and/or for controlling the catalytic converter exhaust system. As the temperature rises, the electrical resistance of the honeycomb body also rises. This can be used to monitor and control an electrical heater. In addition to the effect that the heating power absorbed by a catalytic converter carrier body decreases when the voltage remains constant, the heating process can also be stopped when the electrical resistance falls below a predeterminable threshold. The reheating of a catalytic converter whose operating temperature, for example in slow-moving traffic, has fallen below the ignition temperature of the catalytic reaction can also be triggered by a resistance measurement. The heating circuit itself can be used to measure the resistance by switching it on periodically for a short time and

35the absorbed heat output or a quantity proportional to this heat output is measured.

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Examples of embodiments and the environment of the invention are shown in the drawing, partly schematically. Figure 1 shows a partially two-line exhaust system of a motor vehicle with different positions for the start and main catalysts,

Figure 2 shows a basic circuit for electrically heated catalysts,

Figure 3 shows a schematic circuit for disk-heated catalysts.

iC Figure A is a diagram showing temperatures in the exhaust or catalytic converter system of a motor vehicle as a function of the time after the start of operation,

Figure 5 shows a meandering layered catalyst carrier body,

Figure 6 shows a catalyst carrier body with U-shaped sheet metal layers and corresponding current paths, Figure 7 shows a sheet metal stack with constrictions, Figure 8 shows a meander-shaped catalyst carrier body made from this sheet metal stack, Figure 9 shows a section of Figure 8 to illustrate the insulation of the sheet metal stack from the jacket tube, Figure 10 shows an electrically wettable catalyst carrier body made from a sheet metal stack intertwined in opposite directions (S-shape) with insulating intermediate layers,

Figure 11 shows a multi-plate catalyst composed of catalyst bodies according to Figure 10 with a schematically indicated electrical interconnection, Figure 7 shows a further catalyst carrier body made of oppositely intertwined sheets with a jacket tube and design of the electrical connections, Figure 13 shows a longitudinal axial section through a catalyst carrier body which is constructed from two plates according to Figure 12.

Figure IA shows a type of installation for electrically conductive catalyst carrier bodies in a schematic representation, partially cut longitudinally,

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Figure 15 and Figure 16 different variants for frontal connecting struts and

Figure 17 shows an electrically insulating positive connection between two sheet metal layers.
5

Figure 1 shows a schematic representation of a partially two-line exhaust system of a motor vehicle. However, the statements made below also apply to single-line systems in which the lower branch 10b, 11b, 12b _and 15b, 16b, 17b, 18b, 19b is omitted. The exhaust system leads oil gases with McW exhaust outlet lines 10a, 10b to a mixing section 13 in which a lambda probe is arranged. From there, exhaust lines 15a, b lead to the main catalysts 17a, 17b, 18a, 18b and from there to exhaust lines 19a, 19b.

Whether the main catalysts consist of just one body or, as shown, of two bodies depends on the size and performance of the engine. Figure 1 shows three possible positions for electrically heated start catalysts. Position 1 is designated 11a, 11b, position 2 is designated 12a, 12b and position 3 is designated 16a, 16b. The advantages and disadvantages of these positions are discussed individually below, but combinations are also conceivable in which two or all of these positions are equipped with heated catalysts. It is also possible to electrically heat the main catalysts 17a, 17b, 18a, 18b themselves, although this requires higher electrical outputs but may make start catalysts superfluous. Position 1 is the usual arrangement for start-up catalysts, whereby the catalysts are heated up quickly due to their proximity to the engine and therefore respond early, but must also endure high thermal cycling. The response in this position can be improved by electrical heating, but the following exhaust gas path bJs to the position of the main catalysts is relatively long, so that the exhaust gases can cool down again shortly after the start of operation, initially up to the main catalyst, so that the

01 08

· ₉ · ··* ··' 89G671 2DE The response of the main catalysts is only improved to a limited extent.

Position 2 is on the one hand a little further away from the engine, so that the alternating thermal loads on the catalyst carrier body are reduced, and on the other hand it is closer to the main catalyst, so that its response is somewhat improved. Position 2 also has the advantage that the catalysts there respond earlier, improving the response of the lambda sensor 14.

Position 3 is favorable in order to quickly promote the response of the main catalysts 17a, 17b, 18a, 18b along with the response of the starting catalysts 16a, 16b. However, due to the distance from the engine, the starting catalysts in this position only respond later, despite heating.

However, starting catalysts, especially electrically heated starting catalysts, have considerable distribution in each of the positions specified, so that it depends on the individual boundary conditions which of the positions or which combination of these positions is particularly favorable. It is not important to you whether the carrier bodies of the main catalysts are ceramic or metallic carriers.

Figures 2 and 3 show schematic circuit diagrams for electrically conductive or heatable catalysts. In Figure 2, the catalyst 24 is supplied with power from a power source 20 via a switch 23. Here, as in the following, the designation +/-/cj indicates that it is irrelevant for the essence of the invention whether the power supply comes from a battery and with direct current or from an alternator and with alternating current. In general, after certain operating states have been reached, further electrical heating of the catalyst will no longer be necessary, which is why the switch 23 is connected to a time relay.

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69 G 6 7 t 2 EN

and the ignition lock 22. With the arrangement shown in Figure 2 it is also possible, which is an essential point of the present invention, in principle to draw conclusions about the current (ie temperature-dependent) resistance R(T) of the catalyst 24. In the simplest case the resistance R can be determined by a voltage measurement 25 and a current measurement 26 from R = j (U voltage; I current), where the voltage can possibly even be assumed to be constant and known. The resistance R in turn is directly proportional to the temperature T.. of the catalyst carrier body. This results in the possibility of self-regulation of the heating process, in that it is terminated when the current falls below a predetermined current I_; _n , because then a sufficiently high temperature T is reached. Furthermore, it is possible to determine by regularly switching on and measuring the heating current for a short time (or by using another resistance measuring system) whether the temperature &tgr;_&kgr; of the catalyst is still above the ignition temperature T _z for the catalytic conversion. If not, electrical heating can be used again.

Furthermore, recording the temporal behavior of the resistance R of the catalyst carrier body (in the vehicle itself or during a workshop inspection) enables a conclusion to be drawn about the functionality of the catalyst, since the onset of the exothermic catalytic reaction is noticeable by a rapid increase in the resistance R. A corresponding display in the vehicle, e.g. a green lamp, is easy to implement.

In Figure 3, an electrically heatable catalyst is also supplied with power from a power source 30 via a switch 33, which is connected to the ignition lock 32 via a time relay 31. In this embodiment, the catalyst consists of several individually heatable sub-areas 34, 35, 36, 37, in which the first sub-area 34 can be heated individually and with a higher current, and only later the other sub-areas 35, 36, 37, preferably in

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As is explained in more detail in Figure 1 , various alternative systems can be used when heating electrically heated catalysts. In the diagram in Figure 1 , the ordinate shows temperature T versus time t on the axis. L is the ignition temperature of a hot catalyst , for example 350 °C, denoted by t, the ignition point, i.e. the time at which, without any additional measures, the catalytic reaction will take place to a significant extent.

e \ nsr? &igr; / r. . uio Curve T„ shows the course of the air temp. t.ui /or the catalyst as a function of time rifir; h starting the engine at time t.. The next curve L·, shows the temperature course &Ggr; in a

I '< i >&igr;- 1.1 i sch b( heated catalyst carrier body. If the temperature for a catalyst carrier body is chosen such that the temperature &Ggr;^ is always slightly above the exhaust gas temperature I ₁ t>e, then heat is avoided from the exhaust gas being extracted to heat up the catalyst carrier body.

?ü /«ar cannot heat up the exhaust gas itself significantly with the electrical power, but cooling is avoided. With this operating mode, the ceramic and catalytically active mass of the catalyst is heated from the outside by the

ijtiu Vijii

nt-j-iT' Tfönorl/ii Tfiü &ggr;

f) 1 is heated up to a certain temperature and therefore reaches the temperature at which the (exothermic) reaction begins and automatically causes further heating. Because of the limited electrical power available for heating the catalysts, it may be necessary to use a circuit of the

30f igur &iacgr; initially only a partial area, namely the front jch-jibe of a catalyst with an axial height of about 3.5 to 6 cm, is heated in order to start the exothermic reaction there as quickly as possible. A possible temperature profile for this disk is shown by the T _K2

35. The temperature is very high with a short-circuit current limited to a small area.

Ol il

35Under these specifications, it can be assumed that for the electrical heating of catalysts with 12 volts

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lquickly increased, for example to 600 ⁰ C and then to |

the heating of the other catalyst sections;1

As a result, the first disc cools down again somewhat, but with sufficient preheating it falls below

5no longer reaches the ignition temperature and thus keeps the exothermic reaction with the exhaust gas going, which in turn improves the response of the subsequent sub-areas. The curve T , shows the temperature profile of a catalyst carrier body that is preheated before starting the engine. From the beginning

lOof the preheating at time t until the start time t the temperature stPil rises above the ignition temperature U and no longer falls below it.

At this point, some basic considerations 15 regarding the electrical heating of catalysts should be included. The following points should be taken into account:

ti) If catalysts are to be preheated before the engine is started, their power consumption must be

20should be designed so that the waiting time is not too long, but also that the battery is not put under too much strain. Depending on the concept being pursued, current consumptions of between about 40 and 400 A (for 12 V systems) are taken into account in order not to place too much strain on the battery and to ensure that the response times of the

25 catalysts can be significantly influenced.

b) If the catalysts are activated only after the engine has been started

heated, they can last longer or with higher power §

supplied, however, the permissible load of the | 3C alternator and the required wiring

maximum reasonable current strength must be taken into account. In particular |

must take into account the fire hazard of electrical |

Annexes must be observed. f.

Voltage-operating electrical systems can use currents of around 5 to 400 amperes to heat catalysts or individual catalyst areas. This means that the electrical resistance of the current paths used to heat the catalysts should not exceed or fall below certain values, as already explained in the introduction to the description. For catalyst carrier bodies made up of individual sheet metal layers, the following relationship can be determined for the resistance R:
10

f R = &mdash; ⁱ &mdash;" ¹ ^ * ~ ^s P ^ez · electrical resistance

L = layer length (if different

■ lent for straight and wavy

f sheets)

b = film thickness

(- h = film height

'■ &zgr; = number of layers

If a catalyst is constructed from N catalyst disks with a height of h \ 20, the resistance in series connection must be multiplied by N accordingly.

r The heat generated by a current I in a conductor is:

Q = U. I. t= I. R with Q = heat quantity

U = voltage

I = current

t = time

R = resistance 30

The amount of heat required to heat a body to temperature T is:

35

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Q = c . m . Δ�T with c = specific heat

m = mass

&Dgr;» T = temperature difference .

resulting in a heating time by pure electrical resistance heating of

^r el - U . 1

The actual heating time, taking into account the amount of heat supplied to the catalyst by the engine’s waste heat, is significantly shorter, according to experience only about

_K1 -

The following examples of implementation of the

15The invention shows various possibilities for constructing catalyst support bodies from metallic sheets in such a way that current paths with a resistance suitable for electrical heating are created. The invention is not limited to the embodiments, but is also intended to relate to the expert modifications and equivalent embodiments according to the state of the art. In particular, the sheet metal layers do not have to be alternating smooth and corrugated sheet metal layers, but differently structured sheets, as are known in many variations in the state of the art, can also be used in the same way.

Figure 5 shows a meander-shaped catalyst carrier body 50, which consists of a stack of smooth 51 and corrugated 52 sheets, always provided with deflections 57. In the present embodiment, the stack is formed by four corrugated 52 and three smooth sheet layers 51, whereby the top and bottom of the stack consist of corrugated sheet layers. Electrically insulating intermediate layers 58 are arranged between the meander loops, which ensure direct electrical contact between the individual

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Prevent meandering loops. At the ends of the stack, its sheets are each conductively connected to one another and provided with a power supply line 53 and a power discharge line 54, or suitable connectors. The entire body is arranged in a housing or casing tube 55. On the front sides, the area of the deflections 57 has edge covers 56a, 56b indicated by dashed lines, which on the one hand prevent undesirable currents between the deflections 57 and the housing 55 and on the other hand fix the meandering loops and insulating intermediate layers 58. The resistance of such an arrangement can be varied within wide limits by the number of sheets in the meandering sheet stack. In addition, non-rectangular cross sections can also be filled with this type of arrangement.

Figure 6 shows, by way of example, a catalyst arrangement known per se with U-shaped, smooth 61 and corrugated 62 sheet metal layers, which are fastened at their ends to a supporting wall 65, 66, 69. According to the invention, this arrangement is also divided by insulating intermediate layers 68 and a special subdivision of the supporting wall 65, 66, 69 into electrically conductive 65, 66 sections and an electrically insulating structure 69 in such a way that current paths with a suitable resistance are produced. As indicated by arrows, the current flows successively through various groups of U-shaped, adjacent sheets, with electrically conductive sections of the supporting wall each establishing the connection to the next group. Inside the body, the supporting wall has a continuous electrical connection 67 to an opposite electrically conductive section, so that groups of U-shaped sheets on both sides of the supporting wall 69 are included in the current supply. In this embodiment, the current discharge 64 takes place close to the current supply line 63. The entire catalyst carrier body 60 may also have to be arranged in a jacket tube (not shown), opposite which the outermost sheet metal layers may be arranged.

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must be insulated and through which the power supply line 63 and the power discharge line 64 must be led in an insulated manner if necessary.

A further embodiment of the invention is shown in Figures 7, 8 and 9. Figure 7 shows part of a very elongated sheet stack 70, which consists at least in sections of smooth 71 and corrugated 72 sheet strips. This stack has constrictions 73 at intervals.

Such constrictions can occur either when the s

corrugated sieves Ti «.v are not gradually curved or by squeezing the stack together in the desired areas. It is also possible, for example, to initially produce such a stack without constrictions and to solder at the contact points between smooth 71 and corrugated 72 sheets and only then to squeeze the constrictions together. A catalyst carrier body 80 can be layered from a stack designed in this way, as shown in Figure 8. In principle, this is again a meandering layering, except that the deflections are formed by the constrictions 73 of the stack 70. In this way, desired cross-sectional shapes can be produced more easily and irregularly shaped edge areas can be reduced. The constrictions 73 around which the exhaust gas does not flow can be provided with reinforcements 74 to reduce the electrical resistance in this area. The smooth 81 and corrugated 82 sheets of the stack are electrically connected at the ends and end in a power supply line 83 or a power discharge line 84, which are guided through insulating pieces 85 _; 86 through a jacket tube surrounding the body. The individual meander loops and also the outside of the stack are electrically separated from one another and from the jacket tube by means of insulating layers 88. Figure 9 shows an enlarged section of Figure 8 with an example of possible insulation from the jacket tube. The jacket tube 90 can, for example, have pockets 93 into which ceramic plates

01 16

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inserted and possibly soldered there. These ceramic plates 98 keep the stack of smooth 91 and corrugated 92 sheets at a distance from the jacket tube 90, thereby achieving both electrical and thermal insulation. However, ceramic fiber mats or other ceramic materials can also be used as insulation.

Figure 10 shows another particularly advantageous embodiment of the invention, namely a catalyst carrier body 100 known per se from a stack of smooth 101 and rolled 102 sheets intertwined in opposite directions. Such a structure of catalyst bodies is known per se and is often referred to as S-shaped. This embodiment offers the possibility of providing the top and bottom of the stack with ionizing layers 108 or an insulating coating, whereby a relatively long electrical current path, as indicated by arrows, is created when the stack is intertwined in opposite directions. Its length depends on the ratio of the height of the starting stack to the diameter of the catalyst carrier body. If the sheet metal layers 101, 102 are attached at their ends to electrically conductive half-shells 105, 106 which are insulated from one another, a power supply line 103 and a power discharge line 100A can be attached to these half-shells. The half-shells 105, 106 must be separated from one another by insulating pieces 107, for example, whereby the insulating layers 108 must end precisely in the area of these insulating pieces. The entire arrangement is usually housed in an electrically insulated casing tube (not shown), through which the power supply line 103 and the power discharge line 104 must be led in an insulated manner. In general, the power discharge line can be dispensed with in practically all embodiments if a good conductive connection to the housing and thus to the mass of the motor vehicle is established. In addition, many other applications can also be achieved with sheets intertwined in opposite directions.

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Cross sections are filled in a manner known per se, so that this embodiment is not limited to round cross sections.

If the achievable electrical resistance of an electrically heatable catalyst carrier body constructed according to Figure 10 is not high enough in view of the desired axial length, then an interconnection of several disks arranged one behind the other can be used, for example according to Figure

IG ii. The embodiment shown there consists of four disks 100 of height h connected in series, as shown in Figure 10, the series connection of the individual disks being indicated by half-cylinder shells 116 each enclosing two disks. The entire body has a power supply line 1\3 and up to four power outlets 10A, which can each be switched on or off via short-circuit switches 115a, 115b, 115c. Gaps .118 between the individual disks 100 ensure electrical insulation in the axial direction, while the entire body can be housed in a casing tube (not shown) in an electrically insulated manner. The schematically indicated electrical circuit of this arrangement enables the following mode of operation:
At the beginning, the frontmost disk 100, viewed in the direction of the exhaust gas, can be supplied with a very high current, corresponding to the resistance of the disk, by closing the switch 115a. It therefore heats up quickly according to the beginning of the curve T^ ₂ in Figure k . After a certain time interval, for example 10 seconds, the switch 115a can be opened so that when the switches 115b, 115c are open, all the disks receive a heating current that is a factor of ü lower for further heating. It is also possible to open the switches 115a, 115b and 115c one after the other at predetermined time intervals in order to heat up the catalyst disk by disk with decreasing power. This enables the catalyst to start up quickly at

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19
!Simultaneously high power consumption only for a short time.

Figures 12 and 13 again show an S-shaped, electrically heatable catalyst carrier body in a cross section (Figure 12) and a longitudinal section (Figure 13). In Figure 12, in addition to the actual catalyst carrier body 12U corresponding to Figure 10, made of spirally intertwined smooth 171 and corrugated 122 sheets, the connection of the system and the connections in a jacket tube 127a, 127b is also shown. (Yes casing pipe consists of two Ha 1 bscha ! "n 127a, 1 7 /Ki uiplrhp through liPrami crhe &Igr;&kgr;&igr;&igr;&Igr; Ipninnpn 199- 1 "5&Pgr;>■ 1 PU tri Qr h

are separated from each other <y < . Within these half-shells 127a, 127b and electrically insulated from them run further half-shells 125, 126, which are connected to the power supply line 12^ or.

15rirr :�Lgr;. romab 1 &pgr; line 124. The electrical structure and the insulating layers 128 correspond to those in Figure 10. The lines 123, 124 lead outwards through the ceramic piece 129. As can be seen from Figure 13, for example, two such catalyst carrier bodies 120a, 120b can be accommodated behind one another and electrically connected in series in a jacket tube.

Figure 14 shows, as an example, a catalyst carrier body 140 through which the current I (see arrow) flows essentially in an axial direction, in a meandering manner, and its integration into a jacket tube 1-1 shown in longitudinal axial section. At one end, the catalyst carrier body IAO is connected to the jacket tube IU\ in a highly conductive manner , for example via a metal ring. The other end is separated from the jacket tube 141 by electrically insulating spacers 148, which form a type of sectional connection. This or both end faces have (or have) an electrically highly conductive connecting strut 146, which promotes a uniform introduction of a high electrical current I into the catalyst carrier body 140. The connecting strut 146 projects a little, for example about 3-10 mm, in the axial direction into the

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catalyst carrier body 140 and is connected to its metal sheets | in a highly conductive manner, preferably brazed. At the &eacgr;

Connection bar 146 is an electrical supply line 143 good |

conductively attached, which is connected by an insulating bushing
145 is led out through the casing tube 141. The
Supply line 143 has an elastically deformable area 144
which can compensate for thermal expansion of the catalyst carrier body 140 relative to the jacket tube 141. The
Supply line 143, 144 can for example consist of a bent
thick sheet metal strips made of high-temperature corrosion-resistant

Figures 15 and 16 illustrate various
Designs for the integration of connecting struts into the

Front side of a catalyst carrier body.

Catalyst carrier body 150 in Figure 15, which consists of smooth 151
and corrugated 152 sheets, a straight strut ' 156 is inserted into a corresponding slot in the front side ^:

Figure 16 shows the front side of a catalyst

Carrier body 160 made of approximately S-shaped intertwined

structured sheets 161, 162. The connecting strut , .1.66 is also S-shaped. Such a structure is created
for example, if the connecting strut 166 is inserted into the sheet stack f, from which an S-shaped catalyst

Support body by intertwining the ends of the sheet stack A

arises. f

Figure 17 shows a schematic representation of a form-locking i

connection of two electrically insulated sheet metal layers k

171, 172, which is capable of forming the arrow-indicated -\

to absorb forces in the axial direction. The figure shows a %

Longitudinal section through two touching sheet metal layers 171, 172 in |

Area of such a positive connection 173. A |

Such a positive connection can be achieved, for example, by |

transverse to the longitudinal direction of the catalyst carrier body 1

running grooves or individual beads. A |

01 04 1

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!insulating layer 178, for example made of ceramic material, separates the two sheet metal layers 171, 172 from each other. If the depth d of these grooves or beads or the like is greater than the thickness of the insulating layer 178, this layer

5When subjected to axial loads, the positive connection 173 is not subjected to tensile stress but essentially to compression, which results in a high strength of the connection in the axial direction.

fr lOThe present invention and the mentioned

&Ggr;&eegr;&ugr;&ogr;&igr; um uiiy ju> j. j |_/ &khgr;&ogr; j. &ogr; cxynun &ogr;&agr;. ^ &igr;&igr; j_»xj.ii^j.pj.

; electrical heating of catalysts as well as for the

Heating of main catalysts, provided that sufficient electrical power is available. The interconnection of

15several catalyst carrier bodies in parallel or in series is possible depending on the given circumstances and dimensions. When the engine is running and the alternator is generating electricity, the catalysts can also be heated directly by alternating current, whereby the entire required power is not initially

20must be rectified. In contrast to other electrical devices on the vehicle, the catalyst carrier bodies are insensitive to voltage fluctuations and can therefore also be fed by an unregulated, additional voltage supply, never according to the invention.

25 electrically heated catalyst carrier bodies are suitable for reducing pollutant emissions when there are particularly strict requirements for emissions in the cold start phase of a vehicle. The honeycomb bodies described have their main application in car catalysts, but

30Other applications, e.g. as heater or evaporator for fluids etc. possible.

35

01 05

Claims (1)

· ₂₂ ^: ' ·* 89G671 2DE Protection claims 1. Electrically conductive honeycomb body (50; 60? 80; 100, 110; 120; 140} 150} 160), in particular a carrier body for catalysts, made of wound, stacked or otherwise layered layers of at least partially structured, high-temperature corrosion-resistant sheets (51, 52; 61, 62; 71, 72; 81, 82; 91, 52; 101, 102; 121, 122; 151, 152; 161, 162; 171, 172), which form a plurality of channels through which a fluid can flow, preferably of alternating puddles in the u/oconf 1 &igr; r>hon &pgr; 1 &ogr; 4- &diams;&ogr;&tgr;*&igr; mrl nr> m/\1 "! 4- ä t* Ql &lgr;&pgr;&Kgr;&lgr; uj*~*1-\ j=» -t ^i &lgr; O 1 ö *-% 1-» *-» ***"^ ^v "'**""*''*'"~' ¹ '*"*'' y J. ·■* ^- ** *- * vtivj yvnuij.tui uxt-un^ j &eegr; wu* <->■*. u-*. <_ &ugr; j. *.. &ogr;&igr; r t_ (51, 52; 61, 62; 71, 72; 81, 82; 91 ₁ 92; 101, 102; 121, 122; 151, 152; 161, 162; 171, 172) have a thickness of about 0.03 to 0.12 mm, preferably 0.03 to 0.06 mm, and the honeycomb body (50; 60; 80; 100; 110; 120; 140: 150; 160) is separated by gaps (118^ and/or electrically insulating intermediate layers (58; 68; 88; 98; 108; 128; 148; 178) or coatings with respect to its cross-sectional area and/or its axial extent is electrically divided so that at least one electrical current path is produced through the sheets (51, 52; 61, 62; 71, 72; 81, 82; 91, 92; 101, ,02; 121, 122; 151, 152; 161, 162; 171, 172) with an electrical resistance between 0.03 and 2 0hm, preferably between 0.1 and 1 0hm, in particular about 0.6 Ohm. 2. Honeycomb body according to claim 1, characterized in that the honeycomb body (60; 80; 100) is divided with respect to its cross-sectional area and/or its axial extent into partial regions which are partially electrically insulated from one another by ¹ °C and which are all or groups of which are electrically connected in series by defined electrical connecting bridges (73; 65, 66; 116). 3. Honeycomb body according to claim 1 or 2, characterized characterized in that each electrical current path consists of at least four parallel current-carrying 02 01 89 G 6 7 1 2 OE adjacent sheet metal storage, preferably consisting of eight to twelve. h. Honeycomb body according to claim 3, characterized 5 characterized in that the at least four adjacent sheet metal layers through which current flows in parallel are layered in a meandering manner (57) to form a body (50), whereby intermediate layers (58) effect the mutual insulation of the meandering loops.
10 5. Honeycomb body according to claim A, characterized in that in the area of the deflections (73) the at least four layers lie flat against one another, whereby additional reinforcements (74) which reduce the electrical resistance in these areas can be present. 6. Honeycomb body according to claim 1, 2 or 3, characterized in that the honeycomb body (60) consists of approximately U-shaped bent layers (61, 62) which are electrically insulated from one another in groups by intermediate layers (68) or coatings and which are fastened to a supporting wall (65, 66, 69) , the supporting wall (65, 66, 69) having electrically conductive, mutually insulated sections (65, 66), each of which effects a series connection of two or more groups of layers. 7. Honeycomb body according to claim 1, 2 or 3, characterized in that the honeycomb body (100; 120) consists of a stack of oppositely intertwined sheets (101, 102; 121, 122), the stack having electrically insulating layers (108; 128) or coatings at least on its top and bottom sides, and at least the ends of the sheets on each side of the stack are electrically conductively connected to one another and are each provided with connections (103, 104; 123, 12A) for connection to the two poles of a power source (20, 30). 02 &Pgr;2 ¹ · * · I 1 afc. 89 G 6 7 1 2 EN &Igr;&dgr;. Honeycomb body according to claim 7, characterized in that the honeycomb body (100) has a circular cross-section and the height of the stack is less than or equal to one third of the diameter of the cross-section. 5 9. Honeycomb body according to one of claims 1 to 8, characterized in that several honeycomb bodies (100) are arranged in discs one behind the other and are electrically connected in parallel or in series. 10. Honeycomb body according to one of claims 1 to 9, characterized in that the electrically insulating intermediate layers (58; 68; 88; 108; 128; 148; 178) or coatings of granular, ceramic 15Material applied to the adjacent surfaces, preferably flame-sprayed. 11. Honeycomb body according to one of claims 1 to 9, characterized in that the ₂₀ electrically insulating intermediate layers (58; 68; 88; 108; 128; 148; 178) consisting of ceramic parts or ceramic fiber mats. 12. Honeycomb body according to claim 11, characterized 25 characterized in that ceramic plates (98; 148) soldered to a metallic jacket pipe (90; 141) serve to insulate the sheets. 13. Honeycomb body according to one of claims 1 to 12, 30d characterized in that sheet metal layers (171, 172) which are electrically insulated from one another are prevented from axially shifting against one another by form-locking connections (173), whereby a ceramic intermediate layer (178) is inserted into the form-locking connection for electrical insulation 35 is included. 02 03 &kgr;
W
fs 89 G &dgr; 7 1 2 EN 14. Hub body, in particular according to one of claims 1 to 13, characterized in that in a honeycomb body (140; 150; 160) through which electrical current can flow essentially in the axial direction, at one or 5at least one electrically highly conductive connecting strut (146; 156; 166) is present on each of the two end faces, which improves the uniform distribution of the electrical current density over the cross-section of the honeycomb body (140; 150; 160; 15. Honeycomb body according to claim 14, characterized in that at least one of the connecting struts (146) is connected to an elastic (144) electrically highly conductive, high-temperature-resistant supply line ( 3 ) which is led out through an electrically insulating bushing (145) and which is suitable for high current intensities, for example 50 to 400 A, but can absorb, for example, thermally induced relative movements between the connecting strut (146) and the bushing (145).