CN1090060C - Circular disc shape honeycomb, esp. catalyst carrier - Google Patents

Abstract

The invention concerns a honeycomb element, in particular a catalyst support (3) for the catalytic conversion of exhaust gases in an exhaust system, in particular for an exhaust system in an internal combustion engine, preferably a spark ignition engine. The element in question has a plurality of channels (4) each of which discharges at one end into a central channel (5). The channels (4) curve outwards from the central channel (5) and are bounded by disks (15) which lie contiguously. At least some of the disks (15) have a macrostructure which forms the lateral boundary of the channels (4). A microstructure (19) provided additionally in some or all of the disks (15) can enhance the efficiency of a catalytic conversion process.

Description

Disc-shaped honeycomb bodies, especially catalyst supports

The invention relates to a honeycomb body, in particular a catalyst carrier, for the catalytic conversion of exhaust gas in an exhaust system, in particular of an internal combustion engine, preferably a four-stroke internal combustion engine, the honeycomb body having a plurality of channels, each channel being connected at one end to a central channel. Such catalytically coated honeycomb bodies are also referred to as radial catalytic converters. Such a device can be seen in "Catalytic Converters Going High-Tech", Newsletter of the German Association of Engineers, Issue 38, September 24, 1993, page 11.

The object of the present invention is to further develop the honeycomb body on the basis of this known device in such a way that it improves the catalytic conversion of exhaust gases, for example when used as a catalyst carrier. In addition, the production is simplified.

This object is achieved by a honeycomb body in particular for the catalytic conversion of exhaust gases according to the features of claim 1 . Further features are contained in the respective dependent claims.

The honeycomb body of the present invention is characterized in that each channel extends outward in an arc from the central channel. Using this embodiment allows the channel to be increased without having to change the outer dimensions of the carrier.

The support can be designed flexibly with regard to its external dimensions while achieving the same catalytic surface area. The channels are bounded by discs in contact with each other, at least some of the discs have macrostructures constituting the lateral boundaries of the channels, the height of which is for example about 0.5-5 mm.

The advantage of such a honeycomb structure is the simple production, since such a macrostructure can be obtained, for example, by embossing a disc. Another advantage of this structure is that it is relatively simple to adapt the catalytic surface area to the use of the catalyst support by varying the number of disk-like passages.

Some of the macrostructures of the disks may be curved differently from each other. The channels of the carrier may have the same curvature but different cross-sections. Macrostructures with the same and/or different curvatures can be used for catalyst supports to meet various requirements. By alternately using disks with or without macrostructures or disks with different curvatures of the macrostructures, a combined carrier structure can be produced in order to achieve a defined distance between the disks.

Preferably the channels extend generally inwardly from the central channel. In this way, the involute bodies have the same spacing everywhere, so that the free flow cross-section of the channel in the direction of flow remains approximately constant.

In another preferred embodiment, the macrostructured disks and the microstructured disks are arranged alternately in the device such that the macrostructures intersect the microstructures at an angle. The advantage of this modification is that the microstructure interferes with the flow in the channel causing eddies in the flow. Eddy currents in the flow can cause the flow layer and the diffusion layer on the surface of the catalyst to interfere with each other to improve mass transfer between the exhaust gas and the catalyst.

The microstructure can for example be formed as a relief concentric to the central channel. The term microstructure is understood here to mean structures whose height is only about 5-30% of the macrostructure.

According to a further feature of claim 7, the microstructures form reliefs intersecting the macrostructures at an angle.

The discs with macrostructures may also additionally have microstructures extending at an angle to the macrostructures in order to enhance the catalytic action.

The flow of exhaust gas is preferably from the inside to the outside through the carrier. The central channel is thus communicated with the exhaust gas inlet. The advantage of this procedure is that the operating temperature in the middle of the carrier can reach the temperature required for catalytic conversion relatively quickly. Therefore, the device has a relatively fast reaction speed.

In order to further reduce polluting emissions during the cold start period, the carrier should be heated by electric heating or electromagnetic heating. Electrically heated supports are described, for example, in International Patent WO 92/18245.

Now non-limiting embodiments, advantages and possible applications of the present invention are described below in conjunction with the accompanying drawings, in the figure:

Fig. 1 is the longitudinal sectional view of the first embodiment of device of the present invention;

Fig. 2 is the longitudinal sectional view of the second embodiment of the device of the present invention;

Fig. 3 is the plane view of disc;

Fig. 4 is the disc plane view of band microstructure;

Fig. 5 is a sectional view along the line V-V in Fig. 4;

FIG. 1 shows a device 1 for the catalytic conversion of exhaust gases in an exhaust system. The device has a housing 2 in which a catalyst carrier 3 is housed. The catalyst carrier 3 has several channels 4 . Each channel leads to the central channel 5 . The central channel 5 communicates with the exhaust gas inlet 6 of the housing 2 . The exhaust gas inlet 6 or housing 2 communicates with an exhaust pipe 7 which is part of the exhaust system.

The housing 2 has an exhaust gas outlet 8 communicating with another exhaust pipe 9 . The end 10 opposite the exhaust gas inlet is closed.

The carrier 3 is installed separately from the inside of the housing 2 so that a gap 11 is reserved between the carrier 3 and the housing 2 .

Exhaust gas A from an internal combustion engine (not shown) flows into the central passage 5 via an exhaust pipe 7 and an exhaust gas inlet 6 . The exhaust gas flows out of the carrier from the central channel 5 via the channels 4 of the carrier 2 .

The exhaust gas flows into the exhaust pipe 9 through the gap 11 and the exhaust gas outlet 8 of the housing 2 .

Figure 2 shows another embodiment. The difference between the second embodiment and the first embodiment in FIG. 1 lies in the flow of exhaust gas. In the first embodiment, the exhaust gas flows through the carrier from the inside to the outside, whereas in the second embodiment the exhaust gas flows through the carrier 3 from the outside to the inside.

A deflector 13 is provided in the exhaust gas inlet region 12 to deflect the exhaust gas flow into the gap 11 . This deflector serves fluidly to reduce the pressure loss.

In the embodiment of FIG. 2, the carrier 3 is also electrically heatable. For this purpose, the voltage source 14 is connected via the central channel 5 to the interior of the carrier 3 . The outer surface of the carrier 3 is also connected to a voltage source 14 . The carrier 3 consists of several discs in contact with each other. FIG. 3 shows a disk 15 with macrostructures 16 . The macrostructures 16 form the lateral boundaries of the channel 4 . The channel 4 extends generally involutely from the central region 17 outwards. The disk may additionally be provided with microstructures 20 extending at an angle to the macrostructures.

Figures 4, 5 show discs with microstructures. The microstructure 19 has a relief concentric to the central zone 17 . The central area 17 serves as an opening which becomes the central channel 5 when the carrier is assembled. The microstructures 19 may be provided on only one side of the disk 18 but preferably on both sides. Preferably, they are separated from each other by a distance corresponding to 0.5-10 times the height of the macrostructures 16 .

Due to its flexible structure, the honeycomb body according to the invention can be used even where the available space is very limited.

Claims (12)

1. A honeycomb ceramics particularly a kind of in vent systems in order to the catalyst carrier (3) of catalyzed conversion waste gas, this honeycomb ceramics is made of adjacent disk (15,18), have some passages (4), each passage is the boundary with disk (15,18), each passage (4) leads to a centre gangway (5) with the one end

   It is characterized in that:

   At least some disk (15) has the macrostructure (16) on formation passage (4) border, side, and macrostructure is made the involute shape substantially and stretched out from centre gangway (5).
2. 2. press the described honeycomb ceramics of claim 1,

   It is characterized in that:

   Each passage (4) has the curvature that differs from one another.
3. 3. press the described honeycomb ceramics of claim 2,

   It is characterized in that:

   At least some disk (15) has the macrostructure (16) of different curvature bending.
4. 4. press the described honeycomb ceramics of claim 4,

   It is characterized in that:

   Each passage (4) departs from desirable involute shape and tangentially extends from central area (17).
5. 5. press the described honeycomb ceramics of claim 1,

   It is characterized in that:

   The free flow cross section of passage (4) is invariable substantially on flow direction.
6. 6. press the described honeycomb ceramics of claim 1,

   It is characterized in that:

   The disk (18) that has the disk (15) of a macrostructure (16) and have a microstructure (19) is done installation alternately, and wherein, described macrostructure (16) intersects at angle with microstructure (19).
7. 7. press the described honeycomb ceramics of claim 6,

   It is characterized in that:

   Described microstructure (19) has and the concentric burr of a central area (17).
8. 8. press the described honeycomb ceramics of claim 6,

   It is characterized in that:

   Described microstructure is to be made of the burr that intersects at angle with macrostructure.
9. 9. press one of claim 1-3 described honeycomb ceramics,

   It is characterized in that:

   The disk (15) that has macrostructure (16) also has the microstructure of extending at angle with macrostructure (16).
10. 10. press the described honeycomb ceramics of claim 1,

    It is characterized in that:

    Described carrier (3) is heatable.
11. 11. by the described honeycomb ceramics of claim 10,

    It is characterized in that:

    Described carrier (3) but electric heating.
12. 12. by the described honeycomb ceramics of claim 10,

    It is characterized in that:

    Described carrier (3) but electromagnetism heating.

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