JPS58567B2 - exhaust gas filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas filter for removing reburnable particles from an exhaust gas stream.

It is desirable for internal combustion engines to treat their exhaust gases so that they can be safely released into the atmosphere.

The most serious operational problem in some engines, especially diesel engines, is the presence of solid particles carried in the exhaust gas stream.

The solid particles are usually small amounts of carbon, which result from incomplete combustion of the original hydrocarbon fuel under certain operating conditions.

However, the operating efficiency of the engine
efficiency) is also a contributing factor to the amount of carbon produced.

The presence of relatively large amounts of carbon particles in the exhaust gas stream produces a dark, smoky, undesirable effluent.

Such smoke not only has an unpleasant odor, but also poses a health hazard if produced in large quantities.

Accordingly, various techniques have been proposed in the past for removing or minimizing carbon in the exhaust exhaust stream.

However, in conventional devices, it has been found that although the aforementioned carbon particles can be removed by a suitably configured filter, if too much carbon accumulates on the filter, said filter eventually becomes saturated and/or inoperable.

Carbon particles are generated under all diesel engine operating conditions.

Furthermore, the quantity and quality of the exhaust gas flow produced by an internal combustion engine varies according to the operating characteristics of the engine.

As an example, the temperature range that a diesel exhaust gas stream is exposed to is just above ambient atmospheric temperature and approximately 815.58C (815.58C).
15,000F).

If the engine is operated continuously under conditions where carbon is continuously produced and accumulated in the filter, the filter must be restored from time to time.

Under normal conditions, this restoration is accomplished simply by directing the hot exhaust stream through the filter itself, where it is brought into contact with the carbon.

However, when a large amount of accumulated carbon is burned,
The temperature at that time exceeds the temperature of the exhaust gas.

As a result, the filter is susceptible to thermal damage due to this overtemperature.

The inventive filters disclosed herein are provided for removing carbon from an exhaust gas system at a sufficient or controlled rate without damaging the filter.

The greatest amount of carbon particles will be carried to the filter during engine operating conditions when the exhaust gas is at a relatively low temperature, such as when starting from a cool condition, and at light load or idle conditions.

This exhaust gas stream is directed to the filter reaction chamber and passes through first and second sequentially disposed reaction zones or beds.

The entire flow of exhaust gas within the filter is controlled by a flow diversion valve (
diverter valve).

The valve is configured to be movable or adjustable to control the direction and amount of hot gas diverted from the normal passageway.

As long as the exhaust gas is maintained at a certain low temperature, carbon particles in the gas stream will adhere around each passage of the first reaction bed.

After passing through the first reaction bed, the carbon-free gas is passed to a second reaction bed for further processing to remove any carbon particles still present.

The treated gas is now suitable for release into the atmosphere.

Under heavy load, ie, normal engine operating conditions, the exhaust temperature rises to its normal operating temperature range.

The aforementioned flow diversion valves are automatically regulated.

This valving allows the majority of the exhaust gas flow to bypass the first reaction zone and go directly to the second reaction zone.

In the second reaction zone the hot gas contacts the carbon particles contained therein.

The gas then passes through a filter and is released to the atmosphere.

A flow redirection valve is located in the main flow path of the filter and directs only a small amount of the total exhaust gas flow to the first reaction zone where the carbon remains at heavy loads.

Thus, although said first reaction zone has a major amount of carbon particles, this first reaction zone receives a limited amount of hot exhaust gas during filter recovery;
As a result, it receives only combustion sustaining oxygen.

Thus, carbon combustion is moderated by the limited amount of combustion sustaining oxygen while the recuperative combustion action takes place in the first reaction zone.

The retained carbon particles are thereby burned off at a controlled rate and the particle-free gas passes through the second reaction zone.

It is therefore an object of the present invention to provide an exhaust gas filter of the type which is capable of retaining solid combustible particles from a warm relatively cool exhaust gas stream and which is capable of periodically and continuously recovering its function by burning said particles. Our goal is to provide the following.

Another object of the invention is to provide an exhaust gas filter that is capable of removing solids from a hot exhaust gas stream and providing controlled functional recovery of the filter element.

An embodiment of the present invention will be described below with reference to the drawings.

The carbon particle removal filter 10 consists of a casing 11 made of steel or a metal of similar durable construction.

This casing 11 is shaped to form an internal reaction chamber in the center.

Furthermore, the casing 11 is provided with a conical member 12 which is secured to the front end of the casing by welding or similar joining means.

The conical member 12 has a small diameter inlet portion 13 for sealing communication with a source of hot exhaust gas.

The small diameter inlet section 13 is typically coupled to an engine exhaust manifold or the like.

The diverter 14 is firmly positioned upstream of the filter reaction chamber and has the function of directing and distributing the gas flow.

The gas flow is therefore limited to the front panel 16 at the upstream end of the reaction chamber.
collide with the desired pattern.

The conical member 12 has a peripheral guide wall 17 which is also configured to direct the hot gaseous flow in order to achieve the most effective pattern of gas distribution in the face of the front panel 16.

In one embodiment of the invention, front panel 16 is constructed from a perforated metal member through which gas flow can freely pass.

The front panel can be formed, for example, from a relatively strong concrete reinforcing metal sheet or wire mesh that can be in continuous contact with the hot gas stream without deforming or suffering damage.

The front panel 16 is arranged transversely to the gas flow and is fixed to the peripheral guide wall 17 by welding or other suitable joining means.

The reaction chamber of the casing 11 essentially consists of an extension of round or oblong cross-section, depending on the application for which the filter is applied.

The reaction chamber comprises at least two successively arranged reaction zones.

1st. That is, the first reaction zone is a first reaction bed 19 located at the front end of the reaction chamber adjacent to the front panel 16.
determined by.

The second reaction zone consists of a reaction bed 21 disposed downstream of the first reaction bed 19 in the longitudinal direction.

The hot exhaust gas stream entering the front end of the reaction chamber will thus be guided via beds 19 and 21 in turn.

Then, during filter restoration, the hot gas is diverted in its main flow bypassing bed 19 and directly to bed 21 by the diversion valve described below.

In this condition, only a small amount of hot exhaust gas enters and passes through the first reaction bed 19.

The exhaust gas flow regulating device consists of a flow diversion valve 22.

This valve is placed in effective contact with and regulates the flow of exhaust gas through the exhaust gas filter of the present invention.

The valve 22 is operatively positioned within the reaction chamber to be adjusted between an open position and a closed position.

The transition of the valve to the open position is responsive to the temperature of the exhaust gas.

A conical member 23 is provided at the rear of the casing 11, that is, on the downstream side, for receiving gas without any particles.

After compressing the gas flow, the gas without particles is released through the discharge pipe 24.
be passed to.

The gas is then further processed or released to the atmosphere.

The first reaction bed 19 consists of a bed or matrix constructed of suitable materials to allow exhaust gases to flow easily, but to retain solid particles.

This first reaction bed 19 is formed from typical steel wool or similar shredded material.

When tightly packed, the material of the first reaction bed 19 defines a gas permeable mass through which an integral number of flow paths are formed.

The walls of the passageway formed by the matrix material act to capture or retain carbon particles from the passing gas stream.

In one embodiment of the invention, the first reaction bed 19 consists of an annular body made of metallic material.

This body is shaped to fit the casing 11 and define a central axial passage 26.

The central axial passageway 26 is surrounded by material that creates a reaction zone, and gas flows axially through the passageway 26.

It is provided with radial redirection into the surrounding reaction bed.

Although the first reaction bed 19 is illustrated here as a single annular body, it can also be composed of a series or a plurality of relatively small members.

In this embodiment, separate members are placed adjacent to each other to form a single relatively elongated reaction zone.

Since the first reaction bed 19 is a fragile physical structure, members such as metal sleeves 27, 28 may be used to provide rigidity to the first reaction bed 19.

Each of these sleeves or single container-like members encloses the body and defines inner and outer sleeve structures, which are perforated for the passage of gas.

Each sleeve also has sufficient thickness to not deform due to excessive engine heat.

Exhaust gas thus flows through the walls of the central passageway 26 and around the bed 19.

The bed 19 shown in the figure has a gas inlet section 13 and a discharge pipe 2.
4 are preferably arranged coaxially within the reaction chamber of the casing.

Further, the peripheral surface of the first reaction bed 19 has an annular passage 33
is spaced inwardly from adjacent walls of casing 11 to form a .

The treated gas thus flows into the annular passage 33;
It flows along the longitudinal direction of the casing toward the downstream end of the casing 11.

The first reaction bed 19 is fixedly positioned at the rear end of the reaction chamber by a cross member, for example a mounting ring 30.

Furthermore, this first reaction bed 19 is firmly joined by brazing, welding or other methods.

The mounting ring 30 is supported on the inner wall of the casing 11 and is configured to force the flow of gas from the annular passage 33 into the intermediate chamber 36.

With such an end support structure, the first reaction bed 19 is firmly fixed within the reaction chamber.

However, the first reaction bed 19 can also be supported such that it can move within a limited range in response to temperature changes acting on it.

The second treatment zone is defined by the bed 21.

It is formed almost similarly to bed 19.

especially. Bed 21 extends across the reaction chamber and is constructed without a central opening or passageway 26 as provided in the first reaction zone.

This second reaction bed 21 may be similarly reinforced using a sleeve 32° or similar container formed at least partially around the bed.

Such a device provides a support to prevent the bed from deforming due to the hot, rapidly flowing exhaust gas stream.

A second reaction zone or bed 21 completely occupies the downstream end of the reaction chamber of the filter.

Gases passing through bed 19 and entering intermediate chamber 36 thus enter second reaction bed 21 .

In order to facilitate the treatment of the exhaust gas in the second reaction bed 21, along the wall of the casing 11 something like, for example, a flow deflector can be provided.

The flow diversion valve 22 consists of at least one, preferably a plurality of plates.

The plates are pivoted such that at one point the valve is substantially completely closed across the downstream end of passageway 26.

However, in the open position of the valve 22, the flow redirecting valve 22 moves the plates away from their position across the aforementioned passage 26, such that virtually the entire exhaust gas flow passes through the aforementioned passage 26 and immediately enters the intermediate chamber 36. is being used.

The flow diversion valve 22 is mounted such that one side of each cooperating valve plate is pivoted on a positioning ring 29.

Operationally, the most severe conditions for carbon particle deposition occur in the exhaust stream when the engine is started from cold.

However, carbon build-up during certain operating conditions, particularly at idle or under light load, is normal.

Under these circumstances, the core of the flow of hot exhaust gases as well as the temperature are minimized.

In this way, the exhaust gas having high temperature particles enters the small diameter inlet 13.
Once there, the gas is directed by diverter device 14 and distributed to the face of front panel 16 and further into central axis passageway 26.

During this initial period of operation, the engine remains fairly cold.

As a result, the exhaust gases are in the same state.

Flow redirection valve 22 is biased to a normally closed position to substantially or completely occlude the downstream end of center shaft passageway 26 and prevent exhaust gas flow from exiting the downstream end.

As the hot gas enters the central axis passage 26, the back pressure within this passage directs the gas flow to the radially outer first reaction bed 19.
be pushed away.

Within the reaction bed 19 the carbon particles come into contact with and are retained by the walls of steel wool or other reaction medium.

The gas stream from which most of the particles have been removed is transferred to the first reaction bed 1.
9 and enters the peripheral annular passage 33 defined by the inner wall of the casing 11 .

Since the outer surface of the inner wall of the casing 11 is exposed to the atmosphere, it is normally kept relatively cool.

As a result, the exhaust gas flowing along the wall is also cooled down to a certain temperature depending on the ambient temperature.

The exhaust gas flow is then directed towards the rear end of filter 10 and enters intermediate chamber 36 through an opening in one locating ring 30.

The filtered exhaust gas stream then enters the second reaction bed 21 .

This bed 21 retains the remaining carbon particles and the gas free of any particles is removed via the rear panel 38.

This flow is then compressed and the conical member 2
3 to the discharge pipe 24.

After a period of operation, if the engine is idle or at low speeds, the relatively cool exhaust gases will eventually cause carbon particle build-up or build-up.
up).

Such accumulation of carbon particles occurs in the first reaction bed 19.
is concentrated in particular, and only a small amount accumulates in the second reaction bed 21.

However, once the engine is heated to operating temperature under normal load conditions, the temperature quickly rises and the exhaust gas flow rate and temperature rise proportionally above the carbon ignition point.

Eventually, with this condition of gas flow, the exhaust gas temperature will reach a high enough level to burn the particles held within the bed 19 and carry them in gaseous form through the filter.
Place the second plate in the open position.

This opening action causes the main flow of gas to flow axially through the central shaft passage 26 and directly into the intermediate chamber 36 .

Valve 22 operates in conjunction with a temperature responsive element located within the gas flow path.

Such valve actuation devices are known in the art and are utilized for hot gas bodies, such as in the case of exhaust gases.

Flow redirection valve 22 is designed to operate to an open position in response to a certain temperature.

The valve 22 is designed and the movable plate is configured such that at least a portion of the hot exhaust gas flow is directed radially into the first reaction bed 19.

In the first reaction bed 19, the hot exhaust gas is in contact with the retained carbon particles, igniting the particles and burning them.

However, the combustion of carbon in the first reaction bed 19 is limited because the valve 22 opens and most of the hot gas flow above the carbon ignition temperature is bypassed and only a small amount of the hot gas flow enters the bed 19. .

Therefore, the temperature within the bed 19 during functional recovery is maintained at a certain safe level.

At the downstream end of the first reaction bed 19 the hot exhaust gas enters the annular passage 33 and the intermediate chamber 36 and enters the second reaction bed 2
Sent to 1.

In the second reaction bed 21 some retained carbon particles from the first cold gas stream are combusted in the main stream of hot exhaust gas fed through the open valve 22.

At the downstream end of filter 10 relatively hot combustion gases are directed to discharge pipe 24 .

At this time, the first and second reaction beds 19, 21 are substantially free of carbon particles.

If the engine is operated at a high temperature resulting in a hot exhaust gas stream, the condition of the filter relative to carbon build-up remains relatively stable.

However, if the engine speed is reduced or idled for an extended period of time, the temperature of the exhaust gas will be low enough to accommodate this change, promoting the accumulation of carbon particles in the first reaction bed 19.

This is because the valve 22 returns to its closed position again to redirect the entire flow of exhaust gas in the central shaft passageway 26 towards the first reaction bed 19 .

Modifications of the present invention are possible without departing from the spirit and scope of the invention as described above.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway vertical m1 diagram of a filter according to the present invention as installed in an internal combustion engine, and FIG.
3 is a partially enlarged partial view of the inside of the filter according to the present invention, and FIG. 4 is a diagram for explaining the operation inside the filter. 10... Filter, 14... Current deflector,
19...First reaction bed, 21...Second reaction bed, 22...Flow direction changing device, 2
6... Central axis passage. 3°3... Annular passage, 36... Intermediate chamber.

Claims (1)

[Claims] 1 A casing forming a longitudinal reaction chamber, having an inlet communicating with a source of hot exhaust gas carrying combustible particles and an outlet disposed opposite thereto, and a central axis extending in the longitudinal direction. a first reaction zone comprising a perforated annular body defining a passageway supported within the reaction chamber and longitudinally spaced from the first reaction zone via an intermediate chamber in communication with the first reaction zone; a second reaction zone supported within the reaction chamber so as to close the downstream end of the chamber; and a second reaction zone provided at the downstream end of the central axis passage of the first reaction zone, which a flow redirection device operable to open and close to vary the amount of exhaust gas passing through the first reaction zone, the flow redirection device being in a closed position relative to the lower temperature exhaust gas to direct the entire gas flow to the first reaction zone; 1 reaction zone, and an open position to a predetermined hot exhaust gas such that only a small portion of the exhaust gas is flowed through the first reaction zone and retained within the first reaction zone. An exhaust gas filter for treating a hot exhaust gas stream carrying combustible particles to reduce the particulate component in the exhaust stream, characterized in that the particles are burned and at the same time the remaining exhaust gas volume is passed directly to the reaction zone of cylinder 2. .