GB2512845A

GB2512845A - An Improved Exhaust Filtration Device

Info

Publication number: GB2512845A
Application number: GB201306328A
Authority: GB
Inventors: Barry Mead
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-04-08
Filing date: 2013-04-08
Publication date: 2014-10-15
Also published as: GB201306328D0

Abstract

An exhaust filter (e.g a diesel particulate filter, catalytic converter, or exhaust muffler) comprises an inlet 12 in fluid communication with an outlet 14 via an expansion chamber 16. The expansion chamber comprises an inner core 22 extending in its longitudinal direction, and the flow of gases through the filter is in a substantially longitudinal direction from the inlet to the outlet. At least one fluid injector 28 may be provided in the flow path between the inlet and the outlet. The inner core may comprise a fluid reservoir, which may supply fluid to the injector. The fluid in the reservoir may be heated by the flow of exhaust gases. Two filtration sections 26a, 26b may be provided around the inner core. The inner core may comprise inlet and outlet gas deflector caps 24a, 24b, at least one of which may be removable. Accelerator tubes may be provided around the core so as to achieve a substantially laminar flow. The tubes may be arced to provide rifling.

Description

An Improved Exhaust Filtration Device

Field of the Invention

This invention relates to an improved exhaust filtration device, especially for use as a diesel particulate filter and1or a catalytic converter for a vehicle.

Background to the Invention

Diesel particulate filters require high temperatures in order to operate efficiently to burn off particles. In order to reach these required temperatures, it is recommended that cars run for at least 10 minutes at speeds greater than 40 miles an hour (64 kilometres an hour).

This allows the filter to reach a sufficiently high temperature to regenerate. If a user does not reach high temperatures for a sufficient period of time, the build-up of diesel particulate matter may damage the filter and require an expensive repair.

With catalytic converts, there is a need for the substrate, or catalyst core, to heat up to an operating temperature in a similar manner to the diesel particulate filter. Until the device is heated to its operating temperature, it is of limited value and unfiltered exhaust gases can pass through the exhaust system.

Where diesel powered vehicles and/or those fitted with catalytic converters are used in making short journeys, for example less than five to ten minutes, the device may not reach its required operating temperatLire and thus the removal of harmflLl particles and gases may not occur or may be inefficient, resulting in the pollution of the atmosphere.

Additionally, catalytic converters and particulate filters in their current form impede the flow of exhaust gases, thereby reducing the engine efficiency due to a build-up of back-pressure in the engine manifold, which increases friel consumption.

Summary of the Invention

Accordingly, the present invention is directed to an exhaust filter device comprising an inlet in fluid conmmnication with an outlet via an expansion chamber, the expansion chamber comprising an inner core extending in the longitudinal direction, wherein flow of gases through the filter is in a substantially longitudinal direction from the inlet to the outlet, and wherein at least one fluid injector is provided in the flow path between the inlet and the outlet. Preferably, the at least one injector is positioned at the inlet end of the device.

The introduction of at least one fluid injector within the flow path of the exhaust gases allows one to provide additives into the gas stream. Such additives may be useful in reducing harmful emissions, especially NON. This may be particularly advantageous where the device requires high-temperatures to operate efficiently and so until the device is up to an efficient working temperature, additives may be used to reduce emissions.

Additionally, or alternatively, additives maybe added to the stream to aid with rcgcncrating a particulate filter within the dcvicc.

Preferably, an injection fluid reservoir is connected to the injector such that the fluid in the injection fluid reservoir can be injected into the exhaust gas flow stream. Having a reservoir connected to the device allows one to store additives in a convenient location.

Additionally, the reservoir may be readily accessible to allow for the topping-up of additives or the replacement of the reservoir when its contents are used or close to being uscd.

It is advantageous that the injection fluid reservoir is provided with heating means to heat the fluid contained therein. Providing heating means to heat the additives may allow them to work more efficiently in the gas stream. The heating means may be linked to the engine from which the gases originate, which assists with keeping the engine cooled.

This may be combined with other heat sources.

It may be preferable that the injection fluid reservoir is located within the inner core.

Locating the reservoir within the inner core allows the exhaust gases to heat the fluid contained within the reservoir. This reduces the need to provide separate heating means to the reservoir as the heating can be done passively by the exhaust system itself The invention extends to an exhaust filter comprising an inlet in fluid communication with an outlet via an expansion chamber, the expansion chamber comprising an inner core extending in the longitudinal direction, wherein the flow of gases through the filter is in a substantially longitudinal direction from the inlet to the outlet, and wherein the inner core comprises core fluid reservoir. The core of the device will be heated during operation of the engine to which it is connected. By providing fluid within the a reservoir inside the inner core provides a method of retaining the heat gcncratcd so that when the engine is used again, the fluid may still retain some of the heat and thus not require as longer a time to heat to its operating temperature compare to starting from cold. This is particularly advantageous when the engine is bcing used for short periods with a short time therebetween. The inner core may comprise a good thermal conductor, such as a metal material The usc of a fluid-fillcd corc rcduccs thc time rcquired to heat a particulate filter between short journeys and therefore the present invention allows longer intervals between the need for regeneration of the filter and it also allows regeneration to occur without needing high revolutions of the engine. Additionally, the core may be used to provide thermal regulation to the filter and associated filtration media.

Preferably, the core fluid reservoir is provided with heating means to heat fluid contained thcrcin. In addition to thc fluid in thc reservoir rctaining residual hcat from prcvious usc, providing the fluid with a heat source may further reduce the time required for the device to reach its operating temperature. The fluid may be an inert, or stable, fluid and the heat source provided by way of an electrical heating element Advantageously, the core fluid reservoir comprises a reservoir inlet and a reservoir outlet and an external heating device and wherein fluid can be heated in the external heating device and then passed into the core fluid reservoir via the fluid inlet and exits the core fluid reservoir via the fluid outlet. Using heating means external to the reservoir allows one to more easily access the heating means should it need maintenance. Additionally, the fluid within the system can be readily checked and topped-up or replaced. The use of an external fluid circuit allows for temperature regulation of the inner core.

Alternatively, the reservoir comprises a heating device within its body for heating the fluid therein. By retaining the heating element within the body of the reservoir the system can be more easily installed and rcplaccd.

In a preferred construction, the inner core comprises an inlet gas deflecting cap at the inlet end of the inner core to deflect exhaust gases from the inlet and an outlet gas deflecting cap at the outlet end of the inner core, and wherein at least one of the deflecting caps is readily removable from the inner core. The gas deflecting caps direct and spread the exhaust gases and at the same time create heat and accelerate the gases. Additionally, the caps being readily removable allows access to the core and reservoir, although in some situations it may be desirable to permanently fix the caps in place. Whilst the device is intended to be readily serviceable, the reduction in pollutants, especially those associated with greater exhaust manifold back pressure, will reduce the amount of servicing required ovcr traditional systcms. Furthcrmorc, thc usc of thc dcflccting caps aids in accclcrating thc gases through thc filter, allowing it to pass through at a greater speed or velocity, which in turn reduces the back pressure in the engine manifold and also reduces the local temperature within the manifold thereby allowing the engine to be better tuned. This improves the efficiency of the engine and lowers its carbon footprint. The deflecting caps may be dome-shaped, conical, hemispherical or hemi-ellipsoidal in shape. The deflecting caps may be provided with grooves or fins in order to spin, or rifle, the exhaust gases to aid with them passing more speedily through the device.

It is advantageous that the core is surrounded by at least one filtration medium, and more preferably at least two filtration media. This, or these, may be positioned at each end of the core such that one may be considered an inlet filtration medium and the other an outlet filtration medium. The filtration media may be of the same type or may be of different types. For example, it may be preferred to have a diesel particulate filter at the inlet end and a catalytic converter or acoustic muffling material at the other end. Other media may be employed according to the requirements.

Heat transfers from the inner core to the filtration media, which is particularly important where the media is a catalytic structure. The heating of the filtration media from the core allows for the temperature of the media to be increased quicker than relying on the heat of the exhaust gases alone, thereby allowing for it to be more efficient in a reduced time compared with traditional filtration systems.

In one embodiment, the device is provided with at least one accelerator tube positioned between the inlet and the outlet of the device. There may also be a at least one further acceleration tube along the length of the tube, for example, one at the inlet end of the core and one at the outlet end of the corc. The device may comprise accelerator tubes positioned around the central core/resewoir to increase the velocity of the gases passing through the device. The accelerator tube(s) may be tapered and/or may arc around the core to create a rifling effect on the exhaust gases.

It is possible that a first filtration medium is positioned on the side of the at least one accelerator tube closest to the inlet of the exhaust filter and a second filtration medium is positioned on the side of the at least one accelerator tube closest to the outlet of the exhaust device.

In an advantageous construction the exhaust filter further comprises means for converting at Icast some of the gases passing thcrcthrough to a substantially lamina flow. Creating a lamina flow of gases through the device reduces back pressure in the engine manifold and increases the speed of the gases through the filter.

In one construction, the exhaust filter comprises a longitudinally arced accelerator tube, which is arced around the inner core, to provide rifling of at least some of the exhaust gases. Creating rifling of the exhaust gases accelerates their movement through the filter and reduces back pressure in the engine manifold. Additionally, it aids with the flow of the gases through the filter.

The exhaust filter may be a device selected from a group comprising: a particulate filter; a catalytic converter; and an exhaust muffler. The filter may filter particulate matter, gases, such as NON, or sound. The use of the device as a silencer allows for improved acoustic dampening where muffler media is used as filtration media. The device may be provided with a honeycomb monolithic structure, or a similar catalytic structure, so that it may act as a catalytic convcrtcr.

Brief Description of the Drawings

An embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 is a diagram showing a first embodiment of the present invention; Figure 2 is a diagram showing a second embodiment of the present invention; and Figure 3 is a diagram showing a third embodiment of the present invention.

Detailed Description of Exemplary Embodiments

Figure 1 shows an exhaust filter 10, comprising an inlet 12 in fluid communication with an outlet 14, via an expansion chamber 16, in the form of a cylindrical body. The fluid passage from thc inlct 12 to a first cnd 18 of thc cxpansion chamber 16 outwardly tapcrs, that is to say the diameter of the passage increases as it approaches the expansion chamber 16. The fluid passage from the other end 20 of the expansion chamber 16 to the outlet 14 is inwardly tapered, that is to say the diameter of the passage decreases from the other end to the outlet 14.

An inner core 22 is positioned longitudinally within the expansion chamber 16. The two ends of the inner core 22 are provided with removable dome-shaped deflecting caps 24a and 24b, which extend outwardly in the longitudinal direction away from the inner core 22. The deflecting caps 24 are attached to the inner core 22 by way of a screw-fit connection to allow access to the inside of the inner core 22. The deflector caps 24a and 24b are symmetrical. The inner core 22 is held within the device by way of supports, or flanges (not shown), which may be in the form of flat, circular or tubular supports depending on the requirements and the flow required through the device.

The inner core 22 contains a fluid within its structure. The fluid comprises a high heat capacity and low expansion capacity so as to avoid a large increase in pressure within the core, when the device lOis in use. The device 10 may comprise a pressure release valve in order to protect against undue increases in pressure within the inner core.

Filtration sections 26a and 26b are provided at each end of the inner core 22, adjacent the inlet and outlet deflection caps 24. The filtration sections are provided with filtration materials for filtering hydrocarbon particulate and/or acoustic dampening material absorbing sound energy. Additionally, or altematively, the sections 26 may be provided with a catalyst core, or substrate.

An injector 28 is positioned within the flow path through the filter 10. The injector 28 is connected to a reservoir (not shown), which provides a supply of fluid to the filter 10.

The fluid may be in the form of additives for directly and/or indirectly reducing the pollutants in the exhaust gas. The injector 28, or its reservoir, may be connected to the inner core 22 so that the fluid is taken direct from the inner core or is heated by passing therethrough.

The exhaust gases and sound waves enter the filter 10 through the inlet 12 and arc then directed by the deflecting cap 24a around the inner core 22. Heat from the engine and from the flow of the gases through the filter 10 heats the inner core 22 and the fluid contained therein. The heating of the inner core 22 also heats the filtration sections 26 by conduction and radiation. The heating of the filtration sections 26 and the inner core 22 results in a more efficient filter 10 due it reaching an operating temperature quicker than it otherwise would.

Figure 2 shows an exhaust filter 110 with a similar structure to that of filter 10 of Figure 10. However, the inner core 122 is provided with an inlet 140 and an outlet 142 that extends through the wall of the expansion chamber 1& The inlet 140 is connected to a reservoir (not shown) that provides a supply of fluid. The fluid entering the inner core 122 through the inlet 140 is heated so that the inner core 122 can be heated quicker than relying solely on the use of the exhaust gases. In this way, the device 110 can be heated rapidly to a temperature at which the filtering effects of the device 110 are more efficient rather than waiting for it to heat naturally. Alternatively, or additionally during use of the device 110 over an extended period, the reservoir may be connected to a cooling fluid in order to prevent the device from overheating and to keep the filtration media 126 at a more efficient temperature. In such an embodiment, two reservoirs are used and the supply to thc inlct 140 can switch between them according to the internal temperature of the core 122 or the filter 110. The fluid flows through the inner core 122 and out through the outlet 142, where it can pass back to the reservoir to be reheated, or cooled, and recyclcd around thc systcm.

Figure 3 shows an exhaust filter 210 having a structure similar to that of the filter 110 of Figure 2, which the additional feature of an injection 228, as described in relation to the injector 28 of Figure 1.

The dimensions of the fluid flow path through the filter and the shape thereof including the shape of the inner core, are intended to allow the exhaust gas to enter and leave the filter more rapidly than in existing catalytic converters and diesel particulate filters.

Where the fluid within the inner core, or reservoir supplying the inner core, has a high hcat capacity, the fluid is able to absorb a largc amount of heat whilst the enginc is miming and it retains that hcat for a long period when thc enginc has stoppcd running.

This results in the core having a raised temperature compared to normal filtration systems when a user starts the engine again at a time after previously turning it off This assists with the device reaching an efficient working temperature quicker and so it reduces the level of harmfttl emissions being released into the atmosphere.

The inner core may be provided with a conduit through its centre in order to increase flow and to the core and increase the surface area in contact with the exhaust gases.

Additionally, further conduits throlLgh the core may be provided and may be filled with filtration medium.

Where the filter comprises a catalytic converter, a layer of monolithic honeycomb material maybe provided about the inner core of the filter. The honeycomb material may comprise ceramic honeycomb structure and metallic corrugated matting, coated with precious metals such as platinum, palladium and rhodium. The deflecting caps 24 may reduce the gas turbulence associated with current catalytic converters.

Muffling material may be placed within the outer wall of the filter and a perforated inner wall provided to hold the material in place, such that gases and sound waves can reach the material. By using muffling material that also provides insulation to the catalytic converter, heat may be retained within the catalytic converter. By retaining heat within the converter, the temperature increase required for the catalytic converter to get up to optimum temperature is decreased between shod stops of the engine. Muffling material may also be employed within the path of the exhaust gases, either as one of the filtration media at each end of the core, or in addition thereto.

The filter is generally constructed from stainless steel and is welded such that it is gas-tight, so as to prevent the escape of exhaust fumes other than through the outlet. The filtration/muffling media are materials that are not damaged by the high temperatures and flow rates of the exhaust gases. For example, the materials are chosen so as not to be broken down by high temperatures, nor blown out of the exhaust device by high flow rates. These may be composite materials such as long strand fibre matting enveloped in a metal gauze sheath, single strand fibres, or other effective sound wave absorbing material.

However, where the filter of the present invention employs a cooling system, the filtration media may comprise materials that would otherwise not be employed due to the high and uncontrollable temperatures. The use of the heating and cooling system allows one to maintain a more constant temperature within the filter. The more rapid and constant regulation of the core heat allows the media, whether catalytic or particular filter, to be more effective in cutting the levels of pollutants when the engine is not running at a normal optimum running temperature. Thus, it addresses the inefficiency of current catalytic converters and particulate filters which produce hazardous emissions when they are too cold to work effectively.

The injector may be connected to the inner core such that the fluid contained in the inner core is injected into the flow path of the gases. This allows the fluid to be injected at a similar temperature to that of the rest of the filter. Further injectors may be positioned in the flow path of the exhaust gases. Furthermore, there may be more than one injector present in the flow path and more than one fluid may be injected into the flow path, either from a single injector connected to more than one reservoir or from a plurality of injectors with each connected to a first reservoir or to a second reservoir. The fluid injected from the injector(s) may be later recovered, or captured, filtered and recycled.

The device may be applied to diesel or benzene fuelled engines other than those used in vehicles. For example, it may be applied to exhaust systems for all internal combustion engines, vehicles, including heavy duty machinery for quarries and construction, forklifls and farming equipment, heating systems, especially diesel-fed heating systems, and industrial plant machinery. The invention assists with reducing the amount of fuel consumption of an engine.

The device may be used to filter particulates from the exhaust gases and/or may be used to filter sound in the form of a muffler. Additionally, or alternatively, it may be used as a catalytic converter to filter the gases prior to them being expelled from the vehicle.

The device may comprise a central bore substantially longitudinally and substantially axially along the reservoir.

The device may incorporate a diesel oxidation catalyst.

The inner core may be provided with a cooling mechanism in order to reduce the temperature within the device. Such a system maybe advantageous where the optimum working tcmpcraturc of the filter is less than that to which it is heated during normal operation. The cooling system can thus be employed to regulate the system and to keep the filtration media at its optimum working temperature. Temperature regulation of the core allows for more efficient working of the filter by decreasing the time taken for it to reach an efficient working temperature or by retaining it at an efficient working temperature.

The filter may comprise a combination of features disclosed herein in relation to the filter having a heated inner core and/or an injector system.

Claims

Claims 1. An exhaust filter comprising an inlet in fluid communication with an outlet via an expansion chamber, the expansion chamber comprising an inner core extending in the longitudinal direction, wherein flow of gases through the filter is in a substantially longitLLdinal direction from the inlet to the outlet, and wherein at least one fluid injector is provided in the flow path between the inlet and the outlet.
2. An exhaust filter according to claim 1, wherein an injection fluid reservoir is connected to the injector such that the fluid in the injection fluid reservoir can be injected into the exhaust gas flow stream.
3. An exhaust filter according to claim 2 or 3, wherein the injection fluid reservoir is provided with heating means to heat the fluid contained therein.
4. An exhaust filter according to claim 2, wherein the injection fluid reservoir is located within the inner core.
5. An exhaust filter comprising an inlet in fluid communication with an outlet via an expansion chamber, the expansion chamber comprising an inner core extending in the longitudinal direction, wherein the flow of gases through the filter is in a substantially longitudinal direction from the inlet to the outlet, and wherein the inner core comprises core fluid reservoir.
6. An exhaust filter according to claim 5, wherein the core fluid reservoir is provided with heating means to heat fluid contained therein.
7. An exhaust filter according to claim 6, wherein the core fluid reservoir comprises a reservoir inlet and a reservoir outlet and an external heating device and wherein fluid can be heated in the external heating device and then passed into the core fluid reservoir via the fluid inlet and exits the core fluid reservoir via the fluid outlet.
8. An exhaust filter according to claim 6, wherein the reservoir comprises a heating device within its body for heating the fluid therein.
9. An exhaust filter according to any preceding claim, wherein the inner core comprises an inlet gas deflecting cap at the inlet end of the inner core to deflect exhaust gases from the inlet toward the accelerator tubes, and an olLtlet gas deflecting cap at the outlet end of the inner core, and wherein at least one of the deflecting caps is readily removable from the inner core.
10. An exhaust filter according to any preceding claim, wherein the core is surrounded by at least two filtration mediums.
11. An exhaust filter according to any preceding claim, wherein the exhaust filter further comprises means for converting at least some of the gases passing therethrough to a substantially lamina flow.
12. An exhaust filter according to claim 11, wherein the device is provided with at least one accelerator tube positioned between the inlet and the outlet of the device.
13. A exhaust filter according to claim 12, wherein a first filtration medium is positioned on the side of the at least one accelerator tube closest to the inlet of the exhaust filter and a second filtration medium is positioned on the side of the at least one accelerator tube closest to the outlet of the exhaust device.
14. An exhaust filter according to claim 12 or claim 13, wherein the exhaust filter comprises an longitudinally arced accelerator tube, which is arced around the inner core, to provide rifling of at least some of the exhaust gases.
15. An exhaust filter according to any preceding claim, wherein the filter is a device selected from a group comprising: a particulate filter; a catalytic converter; and an exhaust muffler.
16. An exhaust filter substantially as described herein with reference to and/or as illustrated in any appropriate combination of the accompanying text and/or drawings.