GB2369074A - Exhaust gas conditioning device - Google Patents

Abstract

Electrically conductive needles 9 are mounted helically on a rotatable shaft 8 in a tubular conducive housing 1 so that the shaft rotates in the flow of exhaust gases. The shaft is supplied with a negative potential so that the needles act as a cathode and ionise a high proportion of the noxious substances in the exhaust flow. A CO/CO<SB>2</SB> scrubber is mounted in the outlet end of the housing.

Description

Michael Leonard Lucas EXHAUST GAS CONDITIONING DEVICE TECHNICAL FIELD OF THE INVENTION This invention relates to a device for conditioning exhaust gases for emission into the atmosphere. BACKGROUND In recent years an increasing concern about the effects of widespread emission of greenhouse gases into the atmosphere has resulted in a considerable amount of work aimed at reducing the level of noxious gases and harmful particles in the exhaust emissions from internal combustion engines.

The present invention seeks to provide a new and inventive device which preconditions exhaust gases prior to their release into the atmosphere in such a way as to reduce the level of environmentally undesirable gases and particles. SUMMARY OF THE INVENTION The present invention proposes an exhaust gas conditioning device which includes : - a tubular housing having an inlet and an outlet for exhaust gases; - a plurality of needles mounted within the housing; and - means for applying a high electrical potential to the needles.

The presence of an ionising potential a the discharge nuclei formed by the tips of the needles results in ionisation and oxidation of the gases and particles passing through the device. The needles may carry a positive potential, but superior results are achieved if the needles carry a negative potential to form a cathode so that they emit a stream of electrons.

In a preferred form of the device the needles project from a support which is mounted within the housing. The support may be in the form of a shaft, which is preferably mounted in bearings to rotate within the housing. The shaft may be caused to rotate by provision of at least one helical or parthelical formation. Such formations may be in the form of propeller blades or they may be provided by mounting the needles helically on the shaft.

Preferably the shaft comprises an electrically conductive material and is mounted in bearings which comprise an electrical insulation material such as a ceramic.

The housing is preferably electrically conductive to form an earth cage around the needle assembly.

In a preferred arrangement the outlet of the housing is connected to a scrubber for carbon monoxide or carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings: Figure 1 is a side view of an exhaust gas conditioning device in accordance with the invention, shown partly in longitudinal section; Figure 2 is an end view of a rotatable cathode of the device; and Figure 3 is a side view of part of the cathode.

DETAILED DESCRIPTION OF THE DRAWINGS The device shown in the drawings is suitable for use with both petrol or diesel engines, and comprises a cylindrical housing 1 of stainless steel or other electrically conductive heat-resistant material. The housing has an inlet connector 2 at one end which adapts the diameter of the housing to the exhaust of the engine whilst the opposite outlet end is adapted to receive a scrubber 3 for CO and02' The housing is provided with axially spaced carriers 4 and 5 which hold heat-resistant electrically insulating ceramic bearings 6 and 7 which rotatably support a shaft 8, again formed of stainless steel or other electrically conductive material. The shaft 8 carries a large number of electrically conductive needles 9 of stainless steel, copper etc. , to form a rotatable brush cathode. By way of example, the needles may be about 1.6mm in diameter, and are preferably sharpened at their free ends by being cut-off on an inclined plane. (They could alternatively be sharpened to a point.) Fig. 2 shows the cathode assembly in end view. An annular gap 10 of about 12mm is formed between the sharp ends of the needles and the inside surface of the housing 1. In addition, the needles are mounted on the shaft in helical rows, one of which is shown in Fig. 3, such as to form a plurality of passages which travel helically along the cathode between the rows.

Adjacent to the outlet end of the housing the shaft 8 extends beyond the bearings 7 to carry a slip ring 12. The negative potential output from a high voltage electrostatic generator 13 (preferably between 12 and 20 kv) is fed to the shaft 8 via a feed-through rod conductor 14 carrying a carbon wiper 15 which makes electrical contact with the slip ring 12.

As the exhaust gases pass through the housing 1 the helical structure of the brush cathode causes it to rotate in the bearings 6 and 7. The high negative potential existing at the sharpened tips of the needles 9 relative to the surrounding earth cage formed by the housing 1 presents an ionising potential to the exhaust gases passing through the housing and causes a stream of negatively charged electrons to be emitted into the gap 10. As a result, a high proportion of the noxious gases and particles are oxidised and converted to environmentally acceptable materials such as carbon dioxide, carbon monoxide and water. The scrubber 3 removes carbon monoxide and carbon dioxide to further reduce the toxicity of the output gases. The scrubber may comprise a replaceable cartridge containing charcoal, lime, calcium carbonate and zinc sandwiched with a wire mesh to allow gases to pass through.

Rotation of the brush cathode is not essential, although the turbulence thereby created ensures that the exhaust gases have maximum exposure to the ionising potential so that an optimum level of conditioning is achieved within a relatively short distance. The brush cathode could be caused to rotate by other means such as a propeller mounted at the inlet end of the shaft 8, or the shaft may be driven by a motor.

It will be appreciated that the features disclosed herein may be present in any feasible combination. Whilst the above description lays emphasis on those areas which, in combination, are believed to be new, protection is claimed for any inventive combination of the features disclosed herein.

Claims (11)

1. CLAIMS 1. An exhaust gas conditioning device which includes : - a tubular housing having an inlet and an outlet for exhaust gases; - a plurality of needles mounted within the housing; and - means for applying a high electrical potential to the needles.
2. 2. A device according to Claim 1, in which a negative potential is applied to the needles to form a cathode which emits a stream of electrons.
3. 3. A device according to Claim 1 or 2, in which the needles project from a support element mounted within the housing.
4. 4. A device according to Claim 3, in which the support element is in the form of a shaft.
5. 5. A device according to Claim 4, in which the shaft is mounted in bearings to rotate within the housing.
6. 6. A device according to Claim 5, in which the shaft is caused to rotate by provision of at least one helical or part helical formation.
7. 7. A device according to Claim 6, in which the helical or part helical formation is provided by mounting the needles helically on the shaft.
8. 8. A device according to Claim 5,6 or 7, in which the shaft comprises an electrically conductive material and is mounted in bearings which comprise an electrical insulation material.
9. 9. A device according to any preceding claim, in which the housing is electrically conductive to form an earth cage around the needles.
10. 10. A device according to any preceding claim, in which the outlet of the housing is connected to a scrubber for carbon monoxide or carbon dioxide.
11. 11. An exhaust gas conditioning device substantially as described with reference to the drawings.