WO2018234728A1

WO2018234728A1 - Exhaust treatment device

Info

Publication number: WO2018234728A1
Application number: PCT/GB2018/000094
Authority: WO
Inventors: Peter HOLLOWAY WYNFORD
Original assignee: Holloway Wynford Peter
Priority date: 2017-06-24
Filing date: 2018-06-13
Publication date: 2018-12-27
Also published as: GB202000592D0; GB201710147D0; GB2583804A

Abstract

An internal combustion engine exhaust gas treatment device (11) in which exhaust gases from an engine are passed through a non conductive separation chamber (15) having corona discharge means therein comprising a plurality of tubular electrodes (21) bundled together and each tubular electrode has an oppositely charged electrode (23,24) extending coaxially therein so that particulates in the exhaust gas are ionized and charged particulates migrate to the electrodes (21). The oppositely charged electrodes (23,24) within the tubes (21) are supported and interconnected by conductive support frames (25) located one at each end of the bundled tubes and cleaning means (35) mounted on the frames hinder the agglomeration of charged particles.

Description

EXHAUST TREATMENT DEVICE

Field

This invention relates to a device that reduces carbon particulate emissions from internal combustion engines in particular diesel engines.

Background of the Invention

Devices for cleaning the exhaust gases of internal combustion engines of motor vehicles are well known, the most common form using exhaust gas recirculation and catalytic converters in the exhaust systems. Another method, as shown in JPH04128509-A , uses a trap for trapping the particulates and then oxidizing the unburnt carbon. JP2001123820-A utilizes an ultrahigh speed vortex to separate the particulate matter and then subsequently collect the particulates. Another known technique for the removal of particulate matter from exhaust gases utilizes ion generating means, or like particle charging means, with a grounded collector surface so that the particulates are charged and collected on the oppositely charged collector surface. Such a technique is shown in US6228148-B and in US4478613.

GB2369074-A and GB2452008-A both disclose exhaust gas conditioning devices in which a central elongated electrode is housed in a tubular oppositely charged second electrode . A high voltage electric field is set up between the two electrodes one of which is grounded and ionizes carbon particles which are collected on the grounded electrode. GB2452008-A provides a swirl device to direct gases in a circular motion and the device shown in US4588423 also has a vane structure that moves air in a circular motion. A problem with this technique is the agglomeration or build up of particulates on the collector surface which can result in short circuit between the electrodes and the subsequent failure of the device. The present invention seeks to hinder the build up of particulate matter on the collector surface.

Statements of Invention

According to the present invention there is provided an internal combustion engine exhaust gas treatment device in which exhaust gases from an engine are passed through a non conductive separation chamber having corona discharge means therein comprising a plurality of longitudinally extending tubular electrodes bundled together, each tubular electrode has an oppositely charged electrode extending coaxially therein so that particulates in the exhaust gas are ionized and charged particulates migrate to an electrode, the oppositely charged electrodes within the tubes being supported and interconnected by conductive support frames located one at each end of the bundled tubes and cleaning means mounted on the frames, are operated by the flow of the exhaust gas passing through the chamber to hinder the agglomeration of charged particles . This helps prevent the formation of an electrically conductive pathway between the oppositely charged electrodes .

Preferably, the tubular electrodes are grounded forming an anode and the particle charging electrode extending in the centre of each tube is a cathode. Each supporting frame may comprises a plurality of radially outwardly extending arms and the cleaning means are non-conductive and are located on the outwardly extending arms of the support frame.

Preferably, the separation chamber is a ceramic tubular housing located within a tubular metal container and the bundle of tubes snugly fits within the ceramic housing and is located within the housing by spacers which may be formed integrally with at least some of said tubes. Alternatively, the spacers are secured by adhesive e.g. a heat resistant fire cement, located between the internal surface of the housing and an outer surface of a tube in the bundle.

Preferably, each electrode located coaxially within a respective tubular electrode comprises a conductive filament extending between the two support frames.

Alternatively, the coaxial electrode comprises a wire or shaft extending between the two support frames and having a longitudinally spaced array of needles thereon extending radially of the tubular electrode.

Each tubular electrode may be perforated allowing exhaust gases to flow over both inner and outer surfaces of the tubular housing.

Preferably, each cleamng means is a spinner rotatably mounted on its respective support frame or carrier such that exhaust gases move the spinner relative to the frame. Each spinner may be mounted on a ceramic bearing in turn mounted on the respective radial arm. At least one ceramic bearing, and preferably three, may serve to locate in a co- operating hole in the ceramic housing to locate the frame. The preferred location of each cleaning means is adjacent to and not in contact with the housing. The spinner may be provided with wings so that exhaust gases act on the wings to cause the spinner to move, preferably rotate, relative to the frame .

Preferably, the operation of the corona discharge means is by control means secured to the external wall of the ceramic housing through an aperture in the wall of the container and the control means is located in an aperture in a wall of the container. Alternatively, the control means may be remote from the metal container.

In the preferred method of operation the corona discharge means is activated only once the chamber has reached a predetermined minimum temperature.

In order to reduce the build-up of back pressure within the engine, the internal diameter of the ceramic housing is matched with the transverse areas of the corona discharge means so that the transverse area open for gas flow is substantially equal to the cross-section transverse area of the internal combustion engine exhaust.

Description of the Drawings

The Invention will be described by way of Example and with reference to the

accompanying drawings in which:

Fig.1 is an isometric view of an internal combustion engine exhaust treatment device according to the present Invention,

Fig.2 is a schematic of a longitudinal section of the exhaust treatment device shown in Fig.l,

Fig.3 is an end view in the direction of arrow A in Fig.2,

Fig.4 is a view of the frame and cleaning rotors shown in Figs 2 & 3 , Fig.5 shows an electrode bundle within the ceramic housing,

Fig. 6 shows an alternative means of locating the electrode bundle within the ceramic housing,

Fig.7 an electrode having an alternative form,

Fig. 8 is a block diagram of the control system for the device,

Fig. 9 is an end view of an alternative electrode bundle,

Fig. 10 is a end view of the bundle in Fig. 9 showing the support frame for the central electrodes

Fig 11 is a view of the support frame and cleaning rotors of Fig. 10, and Fig.12 is an isometric view of the electrode assemblies within the ceramic housing.

Detailed Description of the Invention.

With reference to Fig.1 , there is shown an external view of an exhaust gas treatment device 11 having a tubular metal cylindrical container 12 with end fittings 13 & 14 for connection into a vehicle exhaust system. Such a system is suitable for both petrol and diesel internal combustion engines. The container 12 is made from a suitable material for example, stainless steel. A tubular ceramic housing 15 is a loose fit within the container 12 and may be secured in place by fire cement of the type used in car exhausts. A typical gap between the housing 15 and the stainless steel container 12 is 2- 3 mm. The container 12 has an elongate aperture 16 in the sidewall thereof so that the ceramic housing 15 is exposed for the attachment of control means 17 to the housing 15 by suitable means such as a high temperature two-part epoxy resin. The control means 17 includes a PCB 18

(printed circuit board} fixed to a thermal insulator 19 which is secured to the housing 15. Now with reference also to Figs. 2 & 3, the ceramic housing 15 with a wall thickness of about 4.5mm forms a chamber having an internal diameter of 61mm having a plurality of metal tubes 21 therein which are bundled together. In this example, there are four tubes closely packed together as shown, however there may between three and nine tubes depending upon the capacity of the engine from which the exhaust is emitted. The tubes 21 are formed from stainless steel having an external diameter of 23mm and a length of 110 mm. The tubes 21 are perforated, each having an total area of perforated holes 22 (see Fig. 7) of about 50% of the area the tube. This allows exhaust gases to pass freely over both internal and external surface of the tube 21. The tubes 21 are welded together to form the bundle, however other suitable methods of securing the tubes together may be used. The bundle of tubes is a fit within the ceramic housing 15.

Within each tube 21 is located a longitudinally extending shaft 23 formed from metal wire about 5mm in diameter and extending beyond each end of its respective tube 21 by between 25 - 45mm. Within each tube 21 , the shaft 23 supports a plurality of radially outwardly extending needles 24 which are about 3mm in length, preferably arranged in a spiral formation around the external surface of the shaft 23. The formation has a pitch of about 2-3 mm. The four shafts 23 are accurately located within the housing 15 by a frame 25 located at each end thereof.

The frame 25 is a diametric cross with radial arms 26 extending outwardly from the longitudinal axis of housing 15. The ends of the arms 26 include end portions 39 that contact the internal surface of the housing so as to locate the frame 25 within the housing 15 and one arm 26A has a radial extension 28 thereon which locates in a cooperating hole 29 in the housing 15 . The extension 28 also passes through the container 12 to serves as both an electrical connector 30 to the control means 17 and as a means of locating the respective frame 25 in the housing.

In another arrangement, described below and best seen in part section in Fig. 3, each end portion 39A extends outwardly to engage a bearing 38 A in a respective hole 40 in the ceramic housing 15 to locate the frame 25 in circumferentially spaced locations around the housing 15. The end portions 39A may extend to contact the inner surface of the container 12. Each arm 26 has a hole 27 formed therein into which an end of a respective shaft 23 is located. The accurate location of each shaft 23 in the frames 25 serves to locate each shaft 23 coaxially of its respective tube 21. One of the tubes 21 is electrically connected to the control means 17 by a connector 34 extending from said tube and through the wall of the housing 15. The bundle of tubes 21 may also be located within the housing 15 by spacers 31 as is best seen in Fig.5. The spacers 31 are secured by adhesive between the internal surface of the housing 15 and the outer surface 32 of a tube 21.

Each tube 21 forms a first electrode, preferably the anode, of a corona discharge means and the corresponding coaxial shaft 23 forms a second electrode, preferably the cathode, of the discharge means. Preferably, the tubes 21 are each electrically grounded with collector surfaces on both the inside and outside of the respective tube. The

corresponding coaxial shafts 23 form a particle charging cathode, surrounded by a respective anode and particles in the exhaust gas are ionized and the charged particulates migrate to the grounded anode. Cleaning means 35, best seen in Fig. 4, are mounted at both ends of the tubes 21 on the frames 25. The cleaning means are mounted at the radially outer end portion 39 of each arm 26 adjacent the inner surface of the housing 15. The cleaning means 35 are operated by the flow of the exhaust gases passing through the housing 15 to hinder the

agglomeration of charged particles which may provide an electrically conductive pathway between the two electrodes, that is via tubes 21 and frames 25. The cleaning means are non-conductive, preferably ceramic. Each cleaning means 35 comprises a spinner 36 rotatably mounted on a respective axle formed by the end portion 39 extending radially outwardly of a support frame arm 26. The spinner 36 has at least two lugs 37, and preferably four. The lugs 37 are circumferentially spaced apart and extend radially outwards such that exhaust gases move the spinner relative to the frame 25. The spinners 36 are each mounted on a non-conductive bearing 38 which is slide fit over the radially outer end portion 39 of the respective arm 26. At its radially inner end, each bearing 38 may sit on a non-conductive washer 141.

This is best seen in part section and as described previously, this shown for the spinner 36A mounted on end portion 39A. The bearings 38A may be extended radially outwardly to locate in co-operating holes 40 in the wall of the housing 15. This serves to secure the frames 25 in position. The preferred location of each cleaning means 35 is adjacent to and not in contact with the housing 15. The exhaust gases act on the lugs 37 to cause the spinner to move, either by vibration or preferably rotation relative to the frame .

An electrical field such as a corona, is set up between the cathodes and the respective anodes. This is operated through the control means 17 which comprises a transformer and multiplier 41 mounted on the PCB 18. The transformer is connected to the cathodes 23 via a connection 30, the radial extension 28 and the co-operating frame 25. Also mounted on the PCB 18 are a control circuit components 42, 43 and a heat sink 44. The control means 17 being connected to the anodes via connector 34. In an alternative arrangement , not shown, the control means 17 can be mounted on the vehicle remote from the container 12 and is connected to the connector 30 to the cathodes by HT lead kept as short as possible. The anode tubes 21 being connected to the anodes 34 via a ground wire. The operation of the device is illustrated with reference to the block diagram shown in Fig. 8. The control circuit components include a programmable processor 43 and a power oscillator 42. The processor 43 is connected to the vehicle ECU 45 and to an exhaust temperature sensor 46 and gas pressure sensor 47 in the housing 15. The pressure sensor may also act as a flow sensor in that the flow through will be related to the pressure. Alternatively, nor shown, a flow sensor may additionally be incorporated in the circuit. The processor 43 is connected to an electrical source 48 from the vehicles electrical system. The processor 43 controls the operation of the power oscillator 42 which is connected to the transformer 41 which sends high voltage DC to the cathodes via connection 28 and is grounded by connector 34 for connection the anodes.

The electrical supply to the transformer 41 is a 2 - 5 amp 12 volts DC supply which may be variable depending upon vehicle use. The transformer is a cascading transformer sealed in resin , or alternatively in a case and immersed in coolant. The transformer raises the output to between 6000 to 30,000 volts, depending upon the size of the ceramic housing and which are delivered to the cathodes 23. The high voltage discharges through the needles 24 to the respective anode 21 forming an electrical discharge means with an electric field within each anode tube 21. A high voltage electric field is set up between the two electrodes 23 & 21 and ionizes carbon particles which are collected on the grounded electrode 21. The perforated tubular electrode allows exhaust gases to flow over both inner and outer surfaces of the electrode.

As the exhaust gases pass through the chamber 12 , the flow of gases causes the cleaning means 35 to move relative to the frames 25 on which they are mounted. This movement hinders the build-up of carbon particles between the frames the end faces of the anode.

The micro processor 43 senses the exhaust gas temperature via the temperature sensor 46 and prevents the operation of the device 11 until a minimum operating temperature is reached. The pressure sensor 47 (flow sensor) will sense the exhaust flow and will cause the micro processor 43 to increase the electrical supply to the cathodes 23 in relation to the exhaust gas flow which will vary in relation the engine mode.

With reference to Figs. 6 & 7, there are shown modifications to the device 11. In Fig 6, there is shown alternative arrangement for spacing the tubes 21 within the ceramic housing 15. The tubes are held coaxial with the housing by four ceramic inserts 51 which are each pushed between adjacent tubes 21 at the ends of each bundle.

In Fig. 7, there is shown an alternative tube 21 A in which the end portions 121 are solid with a slightly increased outer diameter so that the perforated centre sections of bundled together tubes are spaced from each other allowing improved gas flow through the tubes 21A.

In order to reduce the build up of back pressure within the engine , the internal diameter of the ceramic housing 15 needs to be matched with the transverse areas of the tubes 21 and frames 25 so that the transverse area open for gas flow is substantially equal to the cross-section transverse area of the exhaust system. For example, the present example is suitable for connection into a 54.0 mm exhaust fitted for up to a 2.0 litre engine. Other size exhaust pipes must be matched with housings 15 of different diameters and different configurations of corona discharge means. For a vehicle having a 4.0 litre engine may have twin exhausts of 54 mm each and each exhaust is fitted with a exhaust treat ment device according to the present invention. The number of tubes 21, configuration of tubes and the size of the ceramic housing 15 is arranged to minimise any back pressure in the exhaust system.

The ceramic housing 15 may be replaced by a non conductive ceramic coating

With reference now to Fig 9 there is shown an alternative electrode bundle 118 comprising seven tubes 121 for a 54mm exhaust, for example in which the ceramic housing 115 has an internal diameter of about 71.5mm. Six of the tubes are arranged in an outer ring around a central tube 121C. The tubes as previously described are stainless steel perforated with 1.0 mm holes and have a diameter of 23mm . Some of said tubes 121 A in said outer ring, on their respective on the outer surface adjacent the ceramic housing 115 , may be provided with lugs, tabs or spacers 122 at their end portions . The spacers 122 are formed from the metal of the tube deformed outwardly. The spacers 122 ensure that the bundle 118 is an interference fit within the ceramic housing 115. The bundle 118 forms the anode.

Now with reference to Figs. 10, 1 land 12, the cathodes are formed by tungsten wire filaments 123 that extend coaxially of each tube 121. The wire filaments 123 are about 0.45mm in diameter and are supported at each end by a conductive frame or carrier 125. In this example each carrier 125 has an annular outer portion 124 with a diametral strut 126. The circular carrier 125 is provided with seven accurately located holes 127 there being one for each tube 121. The holes 127 are located at the axis of the central tube 121C and are circumferentially spaced evenly around the annular portion 124 . The holes 127 in the annular portion 124 aligning with the axes of the tubes 121in the outer ring.

Each carrier 125 also supports a plurality of cleaning means 135 mounted on the annular portion 124. In the present example there are three cleaning means 135 however between 3-6 cleaning means may used depending upon size of exhaust. The cleaning means 135 are substantially as described for Figs 3 and 4, and are each mounted on a respective radial axle 139 spaced equiangularly around the annular portion 124 extending radially outwardly thereof. The radial axles 139 can be located in respective holes formed in the ceramic housing 115 on bearing 38A and washers 139 as described in reference to Fig 3. The radial axles may project through the ceramic housing 115 to engage the inner surface of the container 12,

A carrier 125 is located at each end of the tube assembly 118 spaced about 25mm therefrom. The tungsten filaments extend between the two carriers 125 coaxially of each respective tube 121. This arrangement is particularly suitable for internal combustion engines having a higher exhaust gas outflows and are suitable for larger diameter ceramic housings 115. The effectiveness of the exhaust treatment can also be improved by further increasing the surface area of the tubes 121. This can be achieved by either an increase in length to say 200-220 mm or by placing two electrode bundles longitudinally in series. If two, or more, bundles of electrodes are arranged longitudinally, sets of cleaning means 35 may be provided on supporting frames located between adjacent ends of the electrode bundles. Another alternative is to alter the surface area of the tubes, preferably by altering the diameter thereof.

Claims

1. An internal combustion engine exhaust gas treatment device in which exhaust gases from an engine are passed through a non conductive separation chamber having corona discharge means therein comprising a plurality of longitudinally extending tubular electrodes bundled together and each tubular electrode has an oppositely charged electrode extending coaxially therein so that particulates in the exhaust gas are ionized and charged particulates migrate to an electrode, the oppositely charged electrodes within the tubes being supported and interconnected by conductive support frames located one at each end of the bundled tubes and cleaning means mounted on the frames are operated by the flow of the exhaust gas passing through the chamber to hinder the agglomeration of charged particles .

An exhaust gas treatment device as claimed in Claim 1, wherein the tubular electrodes are grounded forming an anode and the particle charging electrode extending in the center of each tube is a cathode.

3. An exhaust gas treatment device as claimed in Claim 1 or Claim 2, wherein each supporting frame comprises a plurality of radially outwardly extending arms and the cleaning means are non-conductive and are located on the outwardly extending arms of the support frame.

4. An exhaust gas treatment device as claimed in any one of Claims 1 to 3, wherein the bundle of tubes snugly fits within the ceramic housing and is located within the housing by spacers .

5. An exhaust gas treatment device as claimed in Claim 4 wherein the spacers are formed integrally with at least some of said tubes.

6. An exhaust gas treatment device as claimed in Claim 4 wherein the spacers are secured by adhesive between the internal surface of the housing and an outer surface of a tube in the bundle.

7. An exhaust gas treatment device as claimed in any one of Claims 1 to 6, wherein each electrode coaxially located in a respective tubular electrode comprises a conductive filament extending between the two support frames.

8. An exhaust gas treatment device as claimed in any one of Claims 1 to 6, wherein each electrode located within a respective tubular anode comprises a longi dinally spaced array of needles extending radially of the tubular electrode and mounted on a

longitudinally extending shaft extending between the two support frames.

9. An exhaust gas treatment device as claimed in any one of Claims 1 to 8, wherein each tubular electrode is perforated allowing exhaust gases to flow over both inner and outer surfaces of the tubular housing.

10. An exhaust gas treatment device as claimed in any one of claims 1 to 9 wherein each cleaning means is a spinner rotatably mounted on its respective support frame such that exhaust gases move the spinner relative to the frame.

11. An exhaust gas treatment device as claimed in claim 10 when dependant upon Claim 3, wherein each spinner is mounted on a ceramic bearing in turn mounted on the respective radial arm.

12. An exhaust gas cleaning device as claimed in Claim 11, wherein at least one ceramic bearing locates in a co-operating hole in the ceramic housing to locate the frame.

13. An exhaust gas cleaning device as claimed in any one of claims 1 to 12 , wherein operation of the corona discharge means is by control means connected to a conductive support frame and to the bundle of tubes,

14. An exhaust gas cleaning device as claimed in claim 14, wherein the chamber has a tubular ceramic housing which is held in a tubular metal container and the control means is located in an aperture in a wall of the container .