WO2005113950A2 - Wall flow particulate trap system - Google Patents

Abstract

A wall-flow particulate trap system (2, 450) regenerated by reverse pressure drop of filtered exhaust gas across the porous walls (2, 401) of a plurality of tubular passages (2f) at a pressure drop and duration sufficient to dislodge the collected soot and ash. The system includes a particulate trap (2, 450) having an inlet (2h, IA) and an outlet (2j, OA), a mode valve (6, 405) assembly offset from the inlet of the particulate trap; a remote actuated relief valve (10, 406) offset from the outlet of the at least one particulate trap, a duct rotor (3, 402) intermediate the particulate trap and the mode valve assembly, the duct rotor having a first end (3a) and a second end (3b), the second end of the duct rotor in operative communication with the mode valve assembly and the first end of the duct rotor in fluid communication with the inlet of the particulate trap; and a rotor drive in driving connection with the duct rotor.

Description

Wall Flow Particulate Trap System

Cross-Reference to Related Applications

This application claims priority of U.S. application serial No. 10/846,780 filed on May 14, 2004.

Statement Regarding Federally Sponsored Research or Development

Not Applicable.

Appendix

Not Applicable.

Field of the Invention The present invention relates generally to the field of diesel or other internal combustion engine exhaust systems, and more specifically, to an apparatus and method for reducing the release of emissions and particulates in the atmosphere, and to an apparatus and method for regenerating wall-flow particulate traps using reverse pressure drop across the porous walls at a constant pressure drop and duration sufficient to dislodge and remove the accumulated soot from the passages.

Background of the Invention The U.S. Environmental Protection Agency (EPA) has put in place increasingly stringent standards for particulate and NOx emissions. For example, the October, 2002 standards include 0.1 g/hp-hr for particulates and 2.0 g/hp-hr for NOx. In 2007 these will be further reduced to 0.01 g/hp-hr for particulates and 0.2 g/hp-hr for NOx. Industry has been conducting an intensive program toward achievement of these requirements. PCT Publication WO 03086580 identifies a method of filtering or trapping the particulate from the exhaust and periodically disposing of the collected soot and ash. In common with most other approaches, the system disclosed in the WO 03086580 publication uses a monolithic ceramic trap having passages with porous walls through which exhaust is passed to filter out the smoke particles at very high (90-97%) trapping efficiency. These systems use either wall flow or cross flow traps in multi-trap or single trap configurations. Each of these systems is capable of achieving the EPA particulate standards for 2002 and 2007. Figs. 1A and IB show the wall-flow single trap particulate trap system from the WO 03086580 publication. The principal parts are a trap structure 166, a wall flow particulate trap 160, a rotating duct/valve 162, a rotating duct/valve drive 163, a remote actuated relief valve 173, a seal 166a, a purge duct 169 and a mode valve 168. The wall-flow particulate trap systems disclosed in the WO 03086580 publication use cordierite traps of the well known wall-flow type to filter the exhaust gas by passing it through the porous walls of trap channels. This action removes 90-98% of the particulate and this collects on the inside surfaces of the passages as a layer or cake which after a few hours of operation increases the engine backpressure and must be removed to prevent adverse affect on engine performance. Most competitive trap systems remove this layer of soot by burning it in the trap. To avoid excessive temperatures during this operation, expensive noble metal catalytic coatings are required and ultra low sulfur fuel must be used which will not be broadly available for a number of years. Also, the engines must be operated at a relatively high average load factor or auxiliary heating methods must be used to assure that burn-out occurs before too much soot is collected. Finally, the incombustible ash remains in the traps resulting in increased backpressure and the traps must be periodically cleaned in an expensive and disruptive maintenance operation. The particulate trap systems disclosed in the WO 03086580 publication preclude the above problems by using a reverse flow of pre-filtered exhaust gas to create a constant reverse pressure drop across the trap, or portions thereof, to dislodge and erode the accumulated soot and ash cake and to transport the dislodged particles to an external chamber where in the soot and/or ash are separated from the purge flow for combustion of the soot and storage of the incombustible ash. This approach permits the use of traps of low cost cordierite and the regeneration process has little or no adverse affect on engine performance. This system will provide the 0.01 g/hp-hr particulate emissions standards required by the EPA regulations in the future. There remains a need in the art for a wall-flow single trap particulate trap system that is more compact, less expensive, independent of the engine and its control system and does not require the engine to operate at a given minimum average load factor. There is a need for a wall-flow trap that can be located anywhere in the exhaust system, and would be adaptable to a broad range of vehicles, such as highway trucks, transit buses, school buses, off-highway and many other vehicles.

Summary of the Invention The present invention relates to a single wall-flow trap particulate trap system for filtering exhaust gases. The particulate trap system includes a particulate trap, a mode valve assembly, a remote actuated relief valve, a duct rotor, a rotor drive in driving connection with the duct rotor and means for separating the soot/ash particles from the purge flow and burning the soot and storing the incombustible ash. The duct rotor drive rotates the duct rotor. As the duct rotor rotates, it aligns a central duct with one or more passages of the particulate trap. Depending upon the mode of the system, exhaust flows into or out of the central duct. In other words, the central duct is operative for both normal exhaust flow during filtration and reverse exhaust flow for particulate trap regeneration. The mode valve assembly and the remote actuated relief valve cooperate to maintain a specified mode of system operation. By operation of the mode valve assembly and the remote actuated relief valve, a control system selects a normal filtration mode or a regeneration mode. In normal filtration mode all of the exhaust passes through the trap and is filtered. In regeneration mode the relief valve is actuated to increase the pressure at the exit of the trap to a constant pre-selected level regardless of the engine operating conditions. The mode valve is then changed to the regeneration position and this imposes a constant reverse pressure drop across a small minority of the passages with which the duct is aligned, thus dislodging and removing the soot cake from the affected passages and carrying it out with the purge flow to be separated and burned. The passages that are not aligned with the duct continue to filter engine exhaust and this continuously provides the supply of filtered exhaust necessary for the regeneration process. As the rotor continues to rotate, it aligns with additional passages which, in turn are cleaned, until the entire trap has been regenerated. The control then returns the relief and mode valves to the normal exhaust filtration positions. In some embodiments, the particulate trap system may have more than one particulate trap. In some embodiments, the rotor drive is a ratchet drive mechanism. The ratchet drive has the advantage of operation over a wide variation of tolerances. Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention are described in detail below with reference to the accompanying drawings.

Brief Description of the Drawings The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the embodiments of the present invention and together with the description, serve to explain the principles of the invention. In the drawings: Fig. 1A is a sectional side view of a wall-flow single trap configuration; Fig. IB is a sectional view along section lines A-A in Fig. 1A; Fig. 2A is a sectional side view of a single trap configuration of the wall-flow particulate trap system in a normal filtration mode of operation; Fig. 2B is a sectional view along section lines A-A in Fig. 2A; Fig. 3 is a sectional side view of the single trap configuration of the wall-flow particulate trap in a regeneration mode of operation; Fig. 4 illustrates a ratchet device for rotating the duct rotor component; Fig. 5A is a sectional side view of the single trap configuration of the wall-flow particulate trap system in the normal filtration mode of operation; Fig. 5B is a sectional view along section lines A-A in Fig. 5 A; Fig. 6 is a sectional side view of the single trap configuration of the wall-flow particulate trap system in the regeneration mode of operation; Fig. 7 is a sectional side view of the wall-flow particulate trap system in an alternative embodiment; Fig. 8 is an enlarged sectional side view of a portion of Fig. 5 to show details of the duct rotor and wall-flow trap relationship and the mode valve assembly during normal filtration; Fig. 9 is an enlarged sectional side view of a portion of Fig. 6 to show details of the duct rotor and wall-flow trap relationship and the mode valve assembly during regeneration; Fig. 10 illustrates an alternative duct rotor and wall-flow trap relationship in which a modified wall-flow trap can be used to increase the contact area between the rotary duct rotor and wall-flow trap and the open frontal area of the wall-flow trap; Fig. 11 is an exploded view of the particulate trap system illustrating a method of assembling the previously manufactured purge duct and mode valve assembly and other components of the particulate trap system; Fig. 12A is a sectional side view of the rotor drive in a first embodiment; Fig. 12B is a sectional side view of the rotor drive in a second embodiment; Fig. 13 A is a sectional side view of the single trap configuration of the wall-flow particulate trap system illustrating an alternative duct rotor that will provide more reliable sealing at the footprint between the duct rotor and the trap face; Fig. 13B is a sectional view along section lines A-A in Fig. 13 A; Fig. 13 C is a sectional view along section lines B-B in Fig. 13 B; Fig. 14A is a sectional side view of the single trap configuration of the wall-flow particulate trap system illustrating a second alternative duct rotor; Fig. 14B is a sectional view along section lines A-A in Fig. 14A; Fig. 14C is a sectional view along section lines B-B in Fig. 14B; Fig. 15A is a side view of a separator and igniter assembly including the soot igniter coil and the ash storage receptacle; Fig. 15B is a top view of the separator shown in Fig. 15 A; Fig. 16A is a sectional side view of the single wall-flow trap system which uses a spiral burner means for burning the dislodged soot and disposing of the incombustible ash; Fig. 16B is an enlarged partial sectional side view of the spiral burner;' Fig. 17A is a control circuit; Fig. 17B is the event time scale for the controller of 17A; Fig. 18A is a schematic drawing of an alternative dedicated particulate trap system control in which regeneration is initiated at a pre-selected pressure drop across the wall-flow particulate trap; Fig. 18B is an Event Time Scale for the device illustrated in Fig. 18A; Fig. 19A is a schematic drawing of another alternative dedicated particulate trap system control in which regeneration is initiated after a desired period of operation; Fig. 19B is an Event Time Scale for the device illustrated in Fig. 19A; Fig. 20A is a partial sectional top view of a remote activated relief valve; Fig. 20B is a partial sectional side view of the embodiment of 20A; Fig. 21A is a sectional side view of an alternative remote actuated exhaust pressure relief valve; Fig. 2 IB is an end view of the alternative remote actuated exhaust pressure relief valve; Fig. 21C is a sectional side view of the hemispherical butterfly valves that control the exhaust pressure in the exhaust duct when the relief valve is actuated; Fig. 22A is a partial sectional side view of an alternative embodiment of the remote actuated relief valve; Fig. 22B is partial sectional top view of the embodiment shown in Fig. 22A; Fig. 23A illustrates a rear view of the single trap wall-flow particulate trap system as installed on a highway truck; Fig. 23B illustrates a side view of the single trap wall-flow particulate trap system as installed on the highway truck shown in Fig. 23A; and Fig. 24 illustrates a version of the single trap wall-flow particulate trap system for large engines in which the single trap wall-flow particulate trap configurations are duplicated. Detailed Description of the Preferred Embodiments In this Detailed Description of the Preferred Embodiments, all values given are to be considered as approximate. Referring to the accompanying drawings in which like reference numbers indicate like elements, Figs. 2-4 generally illustrate a wall-flow single trap particulate trap system 450. The particulate trap system 450 is adapted to be disposed in an engine exhaust gas line (not shown). Figs. 2A and 2B illustrate the wall-flow single trap particulate trap system in normal filtration mode. The major components are a trap structure shown generally at 400, a wall-flow particulate trap 401, a combination duct and valve rotor 402, a rotor drive 403, a seal 404, a mode valve 405, a remote actuated relief valve 406, and a separator and igniter (not shown). The trap structure 400 is in fluid communication with the exhaust gas line. The duct rotor 402 is rotated continuously at a very slow rate of speed such as one revolution per fifteen minutes. The duct rotor 402 includes spokes 402c. The duct rotor 402 is piloted by structural member 400a and rotated by a gear set 403a, for example a helical or a worm gear set. Alternatively, the duct rotor 402 is rotated by a ratchet mechanism. Fig. 2B shows the rotational drive mechanism 403 revolved clockwise about 120 degrees such that the motor or other drive device is aligned with a purge duct 407. This permits most of the periphery of the trap system to have about the same diameter as the trap 401. The duct rotor 402 is configured to contain a duct section 402a that passes with very close clearance along a finished face of the wall-flow trap 401. As indicated by Fig. 2B, the pie-shaped duct section 402a of the rotor 402 also is joined with an outer ring 402b that rubs against an outer tube 401a, thus effecting a positive seal. The duct rotor 402 is pressed with a small but constant force against the entrance face of the trap 401 by the seal 404, for example a bellows spring. This assures a positive seal regardless of the dimensional tolerance of the various components or wear of the faces. Alternatively, a system of caged Belleville springs is used to provide an even and constant force. The purge duct 407 is permanently mounted in the trap structure 400, and the face where the seal 404 abuts is machined. The purge duct 407 also connects with the mode valve 405 where it either receives engine exhaust when the mode valve is in the solid position or passes purge flow from the trap 401 to the separator and igniter when the mode valve is in the dashed position (in this figure it is assumed to be in the solid position). The remote actuated relief valve 406 is wide open in the normal filtration mode shown in Fig. 2A It is actuated to provide a substantially constant 30 inches of water (gauge) (hereinafter "in. W.G.") exhaust pressure at the exit of the trap during regeneration mode, regardless of the engine speed and load. In operation, when the unit is in normal filtration mode, exhaust gas enters the trap structure 400 as indicated and a majority of the exhaust passes around the spokes 402c of the duct rotor 402 and thence through the trap 401 wherein it is filtered. A minority of the exhaust flow passes through a small tube 413 to the mode valve 405, thence through the pie- shaped section 402a and through the particulate trap 401 wherein it is similarly filtered by the affected trap passages. This action continues until the pressure drop across the trap 401 reaches about 30 in. W.G. At approximately this engine backpressure, the trap 401 should be cleaned or regenerated. Fig. 3 shows the wall flow single trap particulate trap system in the regeneration mode. When a control system indicates regeneration is necessary by sensing engine backpressure or some other parameter, the relief valve 406 is actuated to provide a substantially constant pressure downstream of the trap 401. The mode valve 405 is then moved to the dashed position thus dropping the pressure in the purge tube to substantially ambient and permitting the pre-filtered exhaust to pass back through the tubes or passages that connect with the duct rotor section 402a. This reverse flow at a substantially constant 30 in. W.G. differential pressure dislodges and erodes the soot accumulated on the trap wall surfaces and carries the dislodged particles out through the purge duct to an external chamber. While 30 in. W.G. is selected as a nominal value and is used in this Specification, it may be necessary to change this relief valve setting as a result of test experience. In the external chamber the soot is ignited and burned and the incombustible ash is stored for periodic removal. These conditions are maintained until the duct rotor 402 has made at least one complete revolution. Upon completion of the regeneration mode, the mode valve 405 is moved to the solid position and the relief valve is de-activated and returned to the wide open position. The system then continues in normal filtration mode until regeneration is again required. In the depicted embodiments of Figs. 2 and 3, it is assumed that the duct rotor 402 is rotated at a constant speed by means of the rotor drive 403, such as a small electrical or air motor, that is connected to the duct rotor 402 by a small helical gear set shown at 403a. Fig. 4 illustrates an alternative method of effecting rotation. In this design, which will be discussed in more detail later, the motor drive at 403 is replaced by a linear actuation drive device 415 that is periodically reciprocated is used to rotate the duct rotor 402 by a ratchet arrangement. As examples, the linear actuation device 415 may be reciprocated by an electrical solenoid or air actuated piston. The ratchet arrangement contains an integral pawl and spring 416 that engages teeth 417 located at the periphery of the duct rotor 402. A spring loaded detent 418 is used to hold the duct rotor 402 in position between movements by the integral pawl and spring 416. The angular movement of the duct rotor 402 during each actuation by the integral pawl and spring 416 can be selected as desired from a very small amount, such as a single tooth, to provide a substantially continuous rotation. The use of the ratchet drive for this type rotation may be preferable to a motor and gear drive because it may be simpler, more compact and less expensive. It also provides a very simple digital method of selecting a desired duct rotor speed. It may be desirable to advance the rotor sufficiently to instantly expose a complete new set of passages to the duct section 402a. The rotational movement and shape of the duct section 402a will have to be rationalized with the geometry of the wall- flow trap to assure that all passages are eventually exposed to regeneration reverse flow. Figs. 5A and 5B illustrate a second embodiment of the wall-flow trap particulate trap system in the normal filtration mode, generally indicated by numeral reference 100. The major components are a trap structure shown generally at 1, a particulate trap 2 having passages 2f, a combination duct and valve rotor 3, a rotor drive 4, a seal 5, a mode valve assembly 6, a purge duct 7, a separator 8, an igniter and ash storage chamber shown generally at 9, and a remote actuated relief valve 10. The trap structure includes an exhaust gas inlet area IA and an exhaust gas outlet area OA. The particulate trap 2 has an inlet 2h and an outlet 2j. The inlet 2h is in fluid communication with the exhaust gas inlet area IA, and the outlet 2j is in fluid communication with the exhaust gas outlet area OA. The mode valve assembly 6 is offset, or spaced apart, from the inlet 2h of the particulate trap system 2 and operatively connected to the duct rotor 3. In the depicted embodiment, the purge duct 7 connects the mode valve assembly 6 and the duct rotor 3. The remote actuated relief valve 10 is located within the exhaust gas outlet area OA and offset, or spaced apart, from the outlet 2j of the particulate trap 2. The mode valve assembly 6 is incorporated as part of the particulate trap system structure 1 in lieu of the external mode valve 405. While the function is basically the same as the valve depicted in Figs. 2-4, the new location of the mode valve assembly 6 makes the entire trap assembly more compact, simplifies the piping and reduces the total cost. In the embodiment depicted in Fig. 5A, the particulate trap system includes a single wall-flow type trap. As an example, the trap may be of the kind produced by Corning, Inc. of

Houghton Park, Corning, New York. While in the depicted embodiment only one particulate trap is shown, those skilled in the art will understand that the system may include more than one particulate trap. In the depicted embodiments, the particulate trap 2 is a Corning® DuraTrap RC 200/19. However, those skilled in the art will understand that other particulate traps, the Corning® EX-80 100/17 for example, may be used. The RC 200/19 traps presents a more uniform passage configuration and present a larger cordierite total surface wear area at the duct rotor 3 and trap module 2 interface. In addition, because more passages per square inch are used and these have thicker walls, the RC 200/19 has a greater mechanical integrity factor than the EX - 80 trap and is less susceptible to damage by run away regeneration. The duct rotor 3 includes a first end 3a and a second end 3b. The second end 3b is connected to the purge duct 7, and the first end 3a is pressed against an inlet face 2a of the trap 2. The seal 5 provides just enough force to assure that the first end 3a remains in contact with the inlet face 2a under all engine operating conditions. In the depicted embodiment, the seal 5 comprises a bellows spring. The contact between the trap 2 and a rotor outer ring 3c and walls of the duct rotor 3 form a "footprint" as shown at 2b of Fig. 5B. This results in a minor duct section 2c at the entrance of the trap 2 that is isolated from the major duct section 2d of the trap 2. In the depicted embodiment, the minor duct section 2c formed by the duct rotor 3 at the trap face 2a encompasses about 20-30 degrees of the trap face near the trap outer diameter. This encloses about 20-30 channels or passages 2f with a 12 inch diameter trap. The minor duct section 2c is selected to assure that all inlet passages 2f are fully open for the same period of time during rotation of the duct rotor 3, even at the center of the trap face 2a. The duct rotor rotational speed and dimensions of the minor duct section are selected to assure that all inlet passages 2f of the trap are open long enough to provide complete removal of the soot and/or ash cake by the reverse flow pressure drop. It is preferred that the minor duct section 2c be made as small as practical to minimize the reverse volumetric flow rate of the pre-filtered exhaust gas. Additionally, the dimensions of the minor duct section 2c will vary in accordance with the diameter of the particulate trap. It will be noted that spokes 3d of the duct rotor 3 are spaced back from the trap entrance face 2a. The spokes are for structural purposes only and have no control function. The duct rotor 3 is supported by a pilot bearing 3g and an outside diameter of tubular member 7a, which is part of the purge duct 7. The duct rotor 3 is continuously rotated by the rotor drive 4 whenever the engine is in operation. In the normal engine operating mode, the remote actuated relief valve 10 is in its fully open position. A mode valve 6a of the mode valve assembly 6 is spring loaded by an actuator (not shown) in the shown position to seat against a mode valve auxiliary member 6b. This permits a small part of the engine exhaust that enters the particulate trap assembly 2 to pass into the purge duct 7 and thence through passages 2f of the trap 2 that are uncovered by the duct rotor 3 at any instant to be filtered. The remainder of the exhaust gas passes around the spokes 3d of the duct rotor 3 and is free to enter any of the remainder of uncovered passages 2f of trap 2, whereby it is also filtered. It will be noted that under these conditions the pressures PI and P3 are equal resulting in no pressure difference across the duct rotor 3, no leakage and no opportunity for any of the exhaust gas to pass to the atmosphere without first having to pass through the trap passages 2f and filtered. During this normal engine operation, the exhaust gas will all be filtered while the duct rotor 3 is very slowly rotated at about 4 to 6 revolutions per hour. After several hours of operation, the trap surfaces will have built up a layer of soot and/ or ash which will significantly increase the pressure drop across the trap 2, and, consequently, the engine backpressure and the particulate trap 2 will have to be regenerated or cleaned. The pressure drop across the trap 2 used to determine when regeneration should occur may vary with the application but generally is in the order of 20-30 in. W.G. It is important that the soot loading of the trap 2 at the time of regeneration does not exceed about 10 to 12 g/liter for the Corning® RC 200/19 trap or 6 g/liter for the Corning® EX-80 trap to prevent uncontrolled regeneration and resultant trap failure in the event that soot ignition occurs at high engine exhaust temperature. The backpressure corresponding to these soot loadings are determined analytically and/or empirically for various trap sizes. Because the present invention can be regenerated on command without need for high temperatures and with a minimal amount of wasted energy, the control should be designed to initiate regeneration at a rather low backpressure for trap safety and minimal adverse effect on engine performance. The reverse flow pressure drop is controlled by the design of the remote actuated relief valve 10. The minimum reverse flow pressure required to provide quick and reliable regeneration is in the range of 20-40 in. W.G., and preferably 30 in. W.G. The maximum reverse flow pressure drop, which is primarily important to prevent unnecessary adverse effect on engine performance during regeneration, is in the range of 30-50 in. W.G., and preferably 40 in. W.G. Fig. 6 shows the wall-flow particulate trap system in the regeneration mode. The first action taken by the particulate trap control system will be to energize a soot igniter coil 9a and actuate the remote actuated relief valve 10. The latter action will close the relief valve 10, restricting the flow of exhaust gas to the atmosphere until it has built up a pressure P2 to a level of at least 30 in. W.G. This pressure P2 will be maintained substantially constant, regardless of the engine speed or load changes. Once the pressure P2 has stabilized and the igniter coil 9a is at high temperature, the control system will energize a mode valve actuator 6e, and the actuator will move the mode valve 6a up to the position shown. This action will stop all flow of exhaust into the purge duct 7 and will open the purge duct 7 to a separator duct 7b leading to the separator 8. Because the purge duct 7 is at ambient pressure, a small flow will pass back through the passages 2f of the trap 2 circumscribed by the minor duct section 2c as a result of the 30 in. W.G. reverse pressure drop. As this reverse flow occurs the soot and/or ash cake will be dislodged and eroded, and the particles will be carried by the purge flow to the separator 8. Because the passages being reversed cleaned at any instant comprise only a small fraction of the total wall-flow trap passages (e.g., 1/15 to 1/24 of the total), the escaping reverse flow will be easily replenished by the continuing forward flow through the major section 2d to provide filtered exhaust. This will permit the pressure P2 to be maintained at 30 in. W.G. under substantially all engine operating conditions. The minor duct section 2c and the pressure level P2 may be varied to accommodate different engine or performance requirements. The duct rotor 3 continues to slowly rotate to sequentially clean all of the trap passages 2f until all passages have been regenerated after one full revolution to the duct rotor 3. In the depicted embodiment, the separator 8 is a cyclone separator. The purge flow which contains the dislodged particles of soot and/or ash will then pass through the cyclone separator 8 wherein the soot and/or ash particles will be moved by centrifugal force against the inner walls of the cyclone and the cleaned purge flow will pass upward through the central passage to the atmosphere. After being forced against the walls of the cyclone separator 8, the particles will migrate downward and pass through the igniter coils 9a, wherein the soot will be burned and the incombustible ash will fall into the ash storage chamber 9b for periodic removal during normal engine and/or vehicle servicing. Following at least one complete revolution of the duct rotor 3, the particulate trap system control will deactivate the mode valve 6a, and the mode valve 6a will be returned by a spring (not shown) to the down position which will isolate the purge duct 7 from ambient conditions. Thereafter, the small flow of exhaust gas into the purge duct 7 will resume and continue through the collection of passages 2f for filtration. Then, the control will deactivate the igniter coil 9a and the relief valve 10 and return these components to their respective position for normal operation. Fig. 7 illustrates, in regeneration mode, an embodiment for use with transit buses, school buses, automobiles and similar vehicles, in which an exhaust system and muffler are placed beneath the body of the vehicle and oriented in a generally horizontal direction. All of the components perform the same functions and the particulate trap system operates in the same manner as was described in conjunction with Fig. 5 and Fig. 6. The difference is that the cyclone separator 8, is transversely located through the center of the particulate trap structure 1, as shown. A tube 8a connects the mode valve assembly 6 with the inlet to the cyclone separator 8. In the depicted embodiment, the tube 8a has a helical twist. The soot igniter 9a and ash storage receptacle 9b are in a convenient location for periodic ash removal. One advantage of this arrangement is that all components are part of the trap structure

1, permitting it to be a totally self contained device except for the control system (not shown) which would be placed in a cool location. An important functional advantage is that the cyclone separator 8 would be kept hot by the surrounding exhaust gas flow. This will minimize any condensation of the combustion generated moisture during normal operation. This could be a problem for vehicles operating in cold weather conditions. In the embodiment depicted in Fig. 7, it should be noted that the rotor drive mechanism and other components of the trap assembly are positioned such that almost the entire periphery of the trap assembly is only slightly larger than the outer diameter of the particulate trap. Additionally, items such as the mode valve actuator and rotor drive are in alignment and positioned towards the bottom of the trap structure. This provides a very compact package that does not substantially increase the overall length of the particulate trap assembly. Accordingly, the embodiment depicted in Fig. 7 can be installed in vehicles where space is limited. As examples, the embodiment may be installed on transit buses, school buses, automobiles, and utility trucks. Moreover, because the present invention does not require heat for regeneration, the trap assembly does not have to be placed close to the engine and may be located in any convenient location, such as the position of the normal engine muffler. Fig. 8 is an enlarged view of the particulate trap system shown in trapping mode during normal engine operation to illustrate more clearly the operation of the duct rotor 3 and its role in controlling flow through the trap 2. This view will also show more clearly the design and operation of the mode valve assembly 6. The particulate trap module 2 is located in a surrounding can 11. The particulate trap module is sealed and held in place by a layer 12 of Interam®. Interam® is a registered trademark of the Minnesota Mining and Manufacturing Co., DBA 3M Co., of St. Paul, Minnesota. This is a standard method of retaining the fragile ceramic wall-flow trap module. It will be noted that the trap 2 is positioned such that its exhaust gas inlet face, projects a small amount (about 0.050 - 0.1 inch) outside an inlet end of the can 11. Following, or prior to, the installation of the trap module 2 in the can 1 1, the inlet face

2a of the trap module is ground and/or lapped to a very flat surface having a fine finish. The face 3a of the duct rotor 3, which is of the shape of the "foot print" that was shown in Fig. 5b, is also ground or lapped to be in a very flat plane and to also have a very fine finish. The trap 2 is assembled with the above two surfaces, 2a and 3a, held in contact with each other with a very low force such as by a bellows spring. As mentioned earlier, this force is just sufficient to assure that the duct rotor 3 does not separate from the trap face 2a during all engine operating conditions. As assembled, the outer ring of the "foot print" rests directly against the trap face 2a covering about a 0.1 inch radius of the trap face at the outer diameter of the trap module 2. The major and minor duct sections 2c, 2d pass across portions of the trap face 2a with a very close clearance. This results in the duct rotor outer ring covering the outer ring of passages of the trap module 2. With the larger 12 inch diameter trap modules, this results in about a 3.5% reduction in the open frontal area and, of course, in the trap capacity. This small loss in open frontal area and trap capacity is not considered serious because the trap 2 can be very easily and efficiently regenerated more often. In some embodiments, a more uniform surface at the outer diameter of the trap where the rotor rests against the trap face (radially inward about 0.1 inches) is obtained by plugging all of the passages 2f located in this area. This plugging of the additional passages will not further reduce the trap open frontal area or its capacity because flow into these additional passages will, in any case, be prevented by the outer ring 3c of the duct rotor 3. The additional plugs are substantially the same as the plugs currently used in wall-flow traps. The additional plugs are added during the process used to plug the alternate passages of current traps prior to final firing of the trap. Following the final firing, the trap inlet face 2a would be ground or lapped as previously discussed. The final ground trap face 2a would have the same pattern of open and plugged passages but these would be surrounded by a smooth solid ring against which the rotor outer ring 3c would rest. This would provide a continuous flat surface to minimize wear and gas leakage. The purge duct 7 has an integral extended tube 7a around which the seal 5 is positioned and also serves as the inner journal for the second end of the rotor 3b. In the depicted embodiment, the seal 5 is a bellows spring. The mode valve assembly 6, which contains the valve 6a, auxiliary member 6b, valve guide 6c, and valve actuator 6e, is made as a sub-assembly and inserted into the purge duct 7. In the depicted embodiment, the mode valve assembly 6 is locked in place by a set-screw which locates in circumferential groove 6f. The purge duct 7 and mode valve assembly 6 may be manufactured as separate apparatus prior to assembly into the trap structure 1. The valve 6a is held in the position shown in Fig. 8 by the actuator 6e and is moved down to seat on member 6b when the actuator 6e is electrically or pneumatically energized. In the depicted embodiment, the valve 6a, valve seat 6b and actuator 6e comprise a sub- assembly and can be removed from the purge duct 7 for repair or replacement. When assembled as part of the total mode valve assembly 6, the valve auxiliary member 6b is slid up into the purge duct 7, thereby compressing a seal 6g. In the depicted embodiment, a set screw is then entered into the circumferential groove around the auxiliary member 6b. Prior to final tightening of the set screw, the auxiliary member 6b is rotated to point the exit duct in the direction desired for piping to the separator 8. When the particulate trap system is assembled, the seal 5 is piloted on the extension tube 7a, and then the duct rotor 3 is placed over the end of the extension tube 7a at the second end 3b. In the depicted embodiment, the seal 5 is a bellows spring that urges the duct rotor 3 toward the particulate trap 2. In operation, in the normal filtering mode, the duct rotor 3 will continuously slowly rotate at any time that the engine is in operation. Because pressures PI and P3 are equal during the filtering mode of operation, there will be no leakage at the duct rotor 3 and the trap 2 interface. The very low force of the duct rotor 3 against the trap face 2a coupled with the very slow rotation speed should result in very long service life of the components. Fig. 9 shows the same components as shown in Fig. 8 but are now changed to illustrate the regeneration mode. The remote actuated relief valve (not shown in this figure) has been actuated to maintain a pressure in the filtered exhaust gas at P2. In the depicted embodiment, P2 is about 30 in. W.G. or greater and which is held substantially constant, regardless of the engine operating conditions. The mode valve 6a has also been moved by the actuator 6c to the upper position to seat against the purge duct 7, thereby blocking off any further entry of exhaust gas into the purge duct. At the same time the mode valve 6 is lifted from the auxiliary member 6b, thereby opening the purge duct 7 to ambient pressure at P3. This permits a strong reverse flow or pressure drop across the porous walls of the passages of trap 2 that are encompassed by the duct of the duct rotor 3 dislodging and eroding the soot and ash and carrying the particles to the separator and igniter (not shown). When in the regeneration mode, pressure PI will be 50 - 60 in. W.G., significantly greater than the near 0 in. W.G. pressure P3 in the purge duct 7. Under these conditions, there will be an additional axial force against the duct portion of the duct rotor 3 of about 12- 15 pounds. This force may reduce as the trap is cleaned, for example to about 6 pounds. This small additional force will tend to close the clearance between the duct rotor 3 and the trap face 2a, further reducing any leakage between the duct rotor 3 and the trap face 2a. Fig. 10 illustrates an alternative embodiment of the duct rotor 3 and the trap 2 interface that provides a larger and more uniform wear surface on the trap and precludes any loss of trap capacity caused by the duct rotor 3 outer ring. In this embodiment, the trap 2 is modified slightly during the trap module manufacture and the outer ring 3c of the duct rotor 3 will have a slightly larger diameter. Following extrusion of the trap module core, a small cuff 2e shown cross hatched is formed at the periphery of the entrance face of the trap 2. In the depicted embodiment, this cuff 2e is about 0.125 inch in radial thickness and about 0.250 to 0.50 inch wide. It is applied to the extruded, but not yet fired, trap core by molding or wrapping the trap core with "green" cordierite tape of the required width to achieve the desired 0.125 inch thickness. The trap module is then fired in the normal manner, thereby bonding the cordierite cuff to unfired trap module in the process. Outer trap module passages 2g are then plugged in the conventional manner to form the complete wall-flow trap with the added cordierite cuff. The cuff 2e might be made of a separate refractory material provided that it will have the same or similar properties, such as coefficient of expansion, wear characteristics and bond qualities. Following the above modifications, the trap face 2a, including the cuff 2e, will be ground and/or lapped to provide the desired flat wear surface. It will be noted from Fig. 10 that with this alternative design, the duct rotor 3 does not block off any of the outer passages 2g. In addition, the cuff 2e will provide additional mechanical strength to the particulate trap 2. Fig. 11 is an exploded view of the particulate trap 2, the duct rotor 3, the purge duct 7, the seal 5, and the mode valve assembly 6. Fig. 11 illustrates a suggested method of assembly of the components. This will permit the pre-manufactured components to be assembled in very accurate relationship with each other without any further machining of the trap assembly. The purge duct 7 is first slipped into a slightly enlarged hole la of the trap structure 1.

An extended pin 14a of an assembly fixture 14 is then inserted into the extension tube 7a of the purge duct 7, and then the assembly fixture 14 is bolted to the structure 1, as shown. The purge duct 7 is then pulled up against a face 14b of the assembly fixture 14. The purge duct 7 is then roughly centered in the hole la, and the purge duct then welded or otherwise fixed in place as an integral part of structure 1. The assembly fixture 14 is then removed. The seal 5 and the duct rotor 3 are then fitted over tubular member 7a followed by assembly of the rest of the parts to structure 1. This procedure assures that the duct/valve rotor 3 is perfectly positioned in the radial and longitudinal directions and that its centerline is parallel to that of the trap structure 1. As assembled, the fit between the duct rotor 3 and the tubular member 7a will be made fairly large. This will locate the duct rotor 3 in a radial position with sufficient accuracy but also will assure that the duct rotor 3 will lie flat against face 2b of the trap at all times. Fig. 12A illustrates the rotor drive 4 as a worm gear set, generally indicated by numeral reference 411. The worm gear set 411 includes a worm 416 and a driven gear 423. The worm 416 is operatively connected to a shaft 425. In the depicted embodiment, the worm 416 forms part of the shaft 425. Fig. 12B illustrates the rotor drive 4 as a ratchet drive arrangement, shown generally at 15, used to drive the duct rotor 3. The component parts include a linear actuator (not shown), actuator shaft 16, a pawl and spring 17, which is attached to the actuator shaft 16, a detent stationary shaft 18, and a detent pawl and spring 19, which is attached to the detent shaft 18. The pawl 17 and the spring pawl 19 each engage the outer ring 3c on the periphery of duct rotor 3. For example, the outer ring 3c may include ratchet teeth. The pawls 17, 19 are each made of a material that will maintain its physical properties under high temperature conditions. In operation, the actuator shaft is moved to the right in the drawing, thus pulling the duct rotor 3 clockwise. At the same time, the detent spring pawl 19 is lifted and then drops into position at the next tooth, thus preventing any reverse rotation as the actuator shaft moves to left to engage another tooth. In the depicted embodiment, the actuator is of the electromagnetic type; however, pneumatic or other means could be used. Rotation can be carried out one tooth at a time, thus providing a substantially constant rotational speed. Alternatively, the stroke of the actuator could be perhaps an inch or more to quickly expose a large number of trap passages. The actuator may receive its energy from a pulse generator 31 (seen for example in Figs. 17 through 19). A major advantage of the use of the ratchet drive for duct rotor 3 is that the distance between the centerline of the ratchet actuator and the mating ring gear teeth may vary a large amount without adversely affecting the operation of the ratchet. This permits rather loose tolerances in the dimensions of the assembled parts and also permits a large change in diameter of the duct rotor 3, which may result from temperature changes, without adversely affecting the effectiveness or life of the ratchet drive. Also, the ratchet ring gear teeth are of the straight spur gear type which will permit the duct rotor to move axially any amount to assure contact between the duct rotor and the trap face. In addition, there is little or no relative movement between the pawls 17, 19 and the ratchet teeth during actuation which might otherwise adversely affect the life of these components which may operate without benefit of lubrication. Finally, the ratchet drive responds to electrical pulses, which is ideal for flexibility of the speed control. Fig. 13 illustrates an alternative duct rotor design. The design presents distortion of the duct rotor causing separation of the reverse flow duct section of the trap leading to excessive leakage in the outer periphery during regeneration. In the embodiment depicted in Figure 13, the spokes have been entirely eliminated. Therefore, there are substantially no imposed radial forces on the duct rotor 30 and its ring gear. This reduces duct rotor thermal distortion and simplifies manufacture. The embodiment of Figure 13 also minimizes the duct rotor to trap "footprint." The "footprint" 31 for the small reverse flow duct 33 is retains its surface area, the contact of the duct rotor ring gear against the trap only extends for about a 45 degree arc. This arc of contact, which may be increased or decreased without departing from the scope of the present invention, is retained to provide stability of the duct rotor against the trap face 35. The ring gear tapers away from the selected arc section until, as shown at 31a, there is a clearance between the ring gear and the trap of about 0.100 inch throughout the majority of the duct rotor periphery. In this design, two conventional retainer rings 34 are used to limit axial movement of the trap. In addition to minimizing the effects of any rotor duct thermal distortion, the axial clearance between the ring gear and the trap provides another advantage. It insures that the reverse flow duct portion of the rotor duct can rest evenly against the trap in response to the spring and pressure axial forces without being constrained by ring gear to trap contact. The portion of the duct rotor that is the "footprint" may be ground flat and smooth, as will the face of the particulate trap itself. Fig. 14 is an alternative duct rotor concept that is substantially the same as that shown in Fig. 13 in its function. However, the reverse flow duct section and the ring gear are initially made as separate parts. In this case the "footprint" 31 of contact with the trap face is entirely determined by the reverse flow duct 33; the ring gear 36 has about 0.100 inch clearance with the trap throughout its periphery. Making the duct rotor from two separate arts has several advantages. The reverse flow duct 33 can be forged or cast from a suitable material such as a low expansion ferric stainless followed by machining of the bearing surface for the pilot bearing and the face against which the spring/seal rests. A small notch or groove would be machined along and above the footprint to facilitate assembly and the face that will bear against the trap will be ground flat and smooth. The ring gear 36 could be transversely cut from large tubing that was pulled through a broach to cut the teeth for the ratchet. Alternatively, the ring gear could be cast, followed by machining if necessary. The reverse flow duct and the ring gear parts would be placed in a fixture and joined by precision welding such as laser or electron beam as shown at 37. It is expected that no machining will be required following assembly. Figs. 15A and 15B illustrate the separator, igniter and ash storage receptacle in more detail. In the depicted embodiment, the separator 20 is a cyclone separator. The cyclone separator 20 may be a standard device and the relative dimensions in the drawing are based on information obtained from Unit Operations of Chemical Engineers, by McCable et al, Fourth Edition, McGraw Hill International Editions (1985). The purge flow is arranged to enter substantially tangentially through a 1/2 x 2 inch passage 21 at a velocity of about 50 feet per second. The flow then spirals downward, centrifugal ly deposits the particles on the inside surface of the cyclone and the cleaned purge flow then exits upwardly through a thimble 22 to the atmosphere. The separated particles 23 in most applications gravitate downward and exit at an end 24 of the cyclone into a suitable storage container. In this application, the particles 23 after gravitating downward are caused to pass through high temperature igniter coils 25 whereby the soot is ignited and burned on contact. The incombustible ash is then deposited in an ash storage receptacle 26. The cyclone separator has the advantage of being very simple with no moving parts and is capable of very high temperature operation. The disadvantage of the simple cyclone separator for many applications is that it is very sensitive to changes in flow rate. In the depicted embodiment, the purge flow rate is determined by the 30 in. W.G. reverse differential pressure and the number of trap passages under going regeneration at any given time. Because the above values are substantially constant regardless of the engine speed and load, the cyclone can be sized to provide the most effective separation of the soot and ash for any given particulate trap system. Fig. 16 illustrates an alternative to the cyclone separator for removing the dislodged soot/ash particles from the regeneration purge stream for subsequent burning of the soot and disposal of the incombustible ash. It is possible that the cyclone separator may not efficiently separate the soot/ash particles under all engine operating conditions. Some of these produce "wet" soot containing a large soluble organic fraction while others produce a very fine dry type of soot. In the discussion of this configuration, the following assumptions are made (some of these would differ for other engine sizes): The engine is rated at 425 hp and uses a single diesel particulate trap that is either a Corning EX-80- 100/17 or a Corning RC-200/19 trap that is 12 in. in diameter and 15 in. long. The exhaust is considered to be air and the exhaust flow rate in pounds per hour is considered to be ten times the engine power output in horsepower. The trap volume is 27.8 liters and the maximum safe soot loading is 6g/liter for the EX-80- 100/17 trap and 12g/liter for the RC-200/19 trap. Finally, it is assumed that the actual regeneration will be accomplished in 15 minutes, which is one complete revolution of the duct rotor (the total regeneration period will be a little longer). A number of the values used were obtained from DieselNet Technology Guide published by Ecopoint Inc. These include Wall-Flow Monoliths Revision 2004.07 from Diesel Filter Materials, and Diesel Filter Regeneration Revision 2004.11 from Diesel Particulate Filters. At full load, the exhaust flow rate for the engine is 4250 pounds per hour, or 70 pounds per minute. In many circumstances, the engine will be loaded with soot/ash under full load operation until the pressure drop is 30 in. W.G. If the trap is then removed from the engine and a reverse differential pressure across the trap of 30 in. W.G. is imposed, there will initially be a reverse flow of 70 pounds per minute and, as the trap soot is removed, this flow rate may increase to 140 pounds per hour as the trap is cleaned. However, as mentioned earlier, in the particulate trap system the 30 in. W.G. reverse pressure drop is imposed across and flow occurs through only 4.2% of the trap passages at any one time during the regeneration period. Therefore, in the depicted embodiment, the soot/ash particles are dislodged and carried out of the trap by a purge flow that is only 2.94 pounds per minute initially with the loaded trap and this increases to 5.88 pounds per minute as the trap passages are cleaned. Average purge flow is assumed to be 4.41 pounds per minute. While this reverse flow regeneration is occurring, the rest of the trap passages are continuing to filter exhaust in normal filtration mode as this assures adequate pre-filtered exhaust for the reverse flow. As the duct rotor rotates, additional loaded passages are exposed to the reverse flow pressure drop and regenerated while other passages are returned to the normal filtration exhaust flow. It is emphasized that as new passages are exposed to the reverse flow pressure drop, a continual flow of dislodged soot will be carried out with the purge flow stream. It should be noted that the 4.41 pounds per minute purge flow rate is a function of the remote actuated relief valve pressure setting. Consequently, the average 4.41 pounds per minute purge flow rate used in this example will remain the same during regeneration, regardless of the engine speed and load at the time regeneration is carried out. Because of the relatively low average flow rate of the purge stream carrying out the dislodged soot/ash particles it is possible to pass the entire purge flow stream through a suitable burner containing an electrically heated igniter. This burner 92 is illustrated in its entirety in Fig. 16 A and in an enlarged partial view in Fig. 16B. Referring first to Fig. 16B, the burner consists of a core of sintered solid cordierite 93 that contains a spiral passage 94 having about a 2 inch O.D. and a pitch of about 1 inch. The cordierite is injection molded in a two-piece die with the spiral passage having ledges 94a upon which a high temperature (1500 - 2000 deg. F) heater element 95, preferably of 80% Nickel, 20% Chromium alloy, can be wound. Following molding, the cordierite is sintered and the heater element 95 is wound in place. This assembly is then slid in place in a larger steel housing 96 and one end of the element 95 is grounded at 95a while the other end is connected to battery voltage. A mat of Interam 97 is placed around the outside of the heater elements to provide thermal insulation and to prevent any possibility of an element short circuit. As shown in Fig. 16A, an electrical thermostat switch or equivalent device 98 is used to control the temperature of the heater element. When regeneration of the trap is required, the control system will first energize the igniter/burner heating element 95. At the same time or shortly after, the control system will

actuate the exhaust relief valve, not shown, to increase the pressure at the trap exit to at least 30 in. W.G. The thermostat control will maintain the igniter/burner heating element at about 1800 deg. F. After a period to allow the heating element 95 to reach the desired temperature, the mode valve 91 will move up to the position shown and the actual regeneration process will begin. This will result in a drop in the purge duct pressure to ambient and a substantially constant reverse pressure drop of 30 in. W.G. will exist across the porous walls of the trap passages that are encompassed by the reverse flow duct. This action will dislodge the soot/ash particles and they will be carried out of the trap by the aforementioned 4.41 pounds per minute average purge flow rate. This flow, accompanied by the dislodged soot/ash particles of various sizes, will be directed to enter the igniter/burner 92 as shown. As the flow passes through the igniter burner it will flow in a spiral path and the resultant centrifugal force will move the soot/ash particles outward until they contact the very hot element 95 and are burned. The above action is seen more clearly in the enlarged partial view of the igniter/burner shown in Fig. 16B. The largest particles will move rather quickly out to contact the white-hot element 95 where they will be burned and release their heat of combustion. As the flow passes through the total length of the assumed 12 inch long igniter/burner, the flow will spin through twelve complete revolutions during which time the smaller soot/ash particles will also gravitate out to the hot element. The above mentioned contact of the soot with the high temperature element may burn all of the soot. However, in addition, the steady flow of dislodged soot/ash particles will provide a continuous release of heat during the regeneration process which will increase the temperature of the purge stream. If regeneration takes place at idle operation during which the exhaust temperature is 200 deg. F, 740 Btu per minute will be required to heat the purge gas to the 1000 deg. F required for ignition of the soot. If the trap is loaded to 6 g/liter there will be about 345 Btu per minute released by the burning soot and it will provide nearly half of this required heat. If the heating element is energized by 5000 watts, an additional 285 Btu per minute will be added. Thus, even under the idle operation scenario there will be nearly enough heat added to heat the purge flow to the ignition temperature of soot. If the trap is loaded to 12 g/liter with an RC-200 trap, about 690 Btu per minute will be released or nearly enough to heat the purge flow stream from the combustion of the soot alone. If regeneration occurs at higher engine loads, as would normally be expected, the purge stream will be heated to a more than adequate temperature to ignite the soot. If the heating element drops below 1800 deg. F, the element temperature control will energize the element electrically. The temperature of the element 95 coupled with the heat of the burning soot will reliably burn the soot as the flow passes through the igniter/burner. As indicated at 99, the purge flow exiting the igniter/burner will pass on to the exhaust stack downstream of the relief valve. The incombustible ash that had accumulated in the trap since its last regeneration will, of course, not be burned. However, the amount of this ash removed during regeneration, even with the large trap used with this assumed application, is only about 1 -2 grams. While it will be emitted from the engine exhaust stack, this tiny amount of ash will be evenly distributed over many miles of vehicle operation. Thus, the necessity of periodically emptying the ash storage chamber would be eliminated. Another advantage of the igniter/burner approach is that it does not depend in any way on gravity for its performance. Therefore, the igniter/burner tube 92 can be placed in any attitude or location that is reasonably close to the mode valve. As stated previously, the particulate trap system does not have to be heated to achieve regeneration and the regeneration process is not affected by the engine speed and load. These factors permit the use of a very simple particulate control system that is entirely separate from the engine and its control system. Fig. 17A illustrates a control that will cause regeneration to occur when the pressure drop across the trap reaches a level, for example, 20 in. W.G. as a selected example, although any desired pressure drop could be used. The parts consist of a power bus 30, a pulse generator 31, a timer motor 32, a P1-P2 pressure switch 33, a relay switch 34, and toggle switches 35, 36, and 37. The toggle switches 35-37 are closed and opened as a function of the rotation of the timer motor 32. The toggle switches 35-37 energize or de-energize corresponding circuits 35a, 36a and 37a. Fig. 14B illustrates an Event Time Scale, which is the timing of these switch events in minutes. It is emphasized that these values can be changed as desired. In the depicted embodiment, electrical power is supplied at all times that the engine is in operation. It can be seen that the pulse generator 31 is therefore in operation when the engine is running. The pulse generator 31 is very similar in function and operation to an automobile turn signal timer. The pulse generator 31 is electrically connected to the rotor drive 4. When the pressure drop across the particulate trap reaches 20 in. W.G. or greater, Pl- P2 momentary pressure switch 33 will close and initiate operation of the timer motor 32. This switch action may not be continuous but after it has been closed for a total time of five minutes, the timer will have rotated to close toggle switch 35, thus energizing circuit 35a, thereby closing relay switch 34, and thereby initiating constant rotation of the timer motor 32. After the timer motor 32 operates for five minutes, the switch 36 will close energizing circuit 36a, which will actuate the remote actuated valve 10, and the soot igniter coil 9a. After another five minutes of operation, the timer will close the switch 37, activating circuit 37a, which will energize the mode control valve 6 (not shown) and reverse flow regeneration will be initiated. This will continue for 20 minutes during which time the duct rotor 3 will have made 1 1/4 revolutions (at a speed of four revolutions per hour). Following this time period, the switches 36 and 37 will open de-energizing circuits 36a and 37a and returning the particulate trap operation back to normal filtration operation. The timer motor 32 will continue to operate for another five minutes at which time switch 35 will re-open, de- energizing circuit 35a. This will, in turn, again open relay switch 34, and stop the rotation of the timer motor 32. Normal operation of the particulate trap system will continue until the pressure drop across the particulate trap again reaches 20 in. W.G. Although this is a very simple control, it is assumed that the entire control, with possible exception of the P1-P2 pressure switch 33 can be designed as a solid state module for smaller size, lower cost and greater reliability. Fig. 18A illustrates another alternative dedicated trap control system that initiates the regeneration process when the exhaust pressure drop across the particulate trap reaches a preselected level. The Event Time Scale for this device is shown in Fig. 18B. This type of control permits the trap to be loaded to a safe level of soot prior to regeneration taking place. It is desirable to allow the trap to accumulate a significant amount of soot in order to achieve the average higher trapping efficiency, especially for the finer particles of soot, that results from the thicker soot/ash cake. The major parts are the power input bus 50, pulse generator 51, timer 53, momentary pressure switch 54, timer input common lead 55, momentary pressure switch input lead 52 and timer output circuits 53a, 53b and 53c. The input bus 50 is energized at all times that the engine is in operation. The pulse generator 51 is a very simple device that creates electrical pulses at a constant frequency. It may be a simple timer or a digital processor clock. The pulses are directed to the duct rotor ratchet actuator to cause it to rotate at about one revolution every fifteen minutes. The pressure actuated momentary switch 54 is used to initiate the regeneration steps when the trap pressure drop reaches its pre-selected value. The timer 53 controls the operation of all of the particulate system components after it has been started in response to a trap pressure drop that indicates regeneration is necessary and these events are shown in the Event Time Scale in Fig. 17B. In operation, starting with the timer motor stationary between regenerations, the timer drive contact 53c is open and the pressure switch 54 is open. As the trap loading builds up, the momentary pressure switch 54 will, on occasion, close as a result of periods when the exhaust pressure drop exceeds its setting. When this occurs, current will flow to the timer motor to ground and it will begin to turn. If the excessive pressure only lasts a few seconds, the switch will open and the timer will stop. If the pressure switch is closed continuously or if the periods of closure total about one minute, the timer 53 will have rotated enough to activate the timer drive circuit 53c as indicated on the drawing. The timer will then run continuously for a period in which the control events are carried out as shown. First, the timer will energize circuit 53a which will activate the remote actuated relief valve 10 and the soot igniter coil 9a. After about five minutes of continued operation, the timer 53 will energize circuit 53b which will energize the mode valve actuator 6a and initiate regeneration. The circuit 53b will remain energized until the duct rotor has made about 1.25 rotations. Following completion of all of the control events, the timer will continue to run for about a minute at which time the timer drive circuit 53c will again be de-energized and the timer will stop. Following the above sequence of events, the trap will have been fully regenerated and the momentary pressure switch 54 will remain open until the trap once again reaches its loading threshold. The above components and their operation may be mechanical devices, or they may be solid state devices. Fig. 19A illustrates an even simpler particulate control that operates entirely separate from the engine and its control. In this control, only a timer motor or other device is used that is arranged to operate switches that are not shown in the drawing. The Event Time Scale for the device is shown in Fig. 19B. The major parts are a power input bus 40, a pulse generator 41, a timer 42, and circuits 41a, 42a and 42b. The input bus 40 is energized at all times that the engine is in operation. Consequently, the pulse generator 41 is also in operation when the engine is operating and this, through circuit 41a, causes the duct rotor 3 to continuously rotate at a speed of four to six revolutions per hour. Energy is also supplied to the timer 42 at all times that the engine is in operation. This causes the regeneration events to occur as simply a function of time. In the depicted example, it has been decided that regeneration is to occur every two hours regardless of the engine speed and load history during this time. The time between regeneration events would be selected based on a "worst case scenario for engine particulate emissions" to assure that regeneration occurred prior to unsafe loading (e.g., > 6g/l) of the particulate trap. When it is time to regenerate the trap, the timer 42 will first energize circuit 42a, as shown in the Event Time Scale, to activate the remote actuated relief valve 10 and the soot igniter coil 9a. After about five minutes of continued operation, the timer 42 will energize circuit 42b, as shown in the Event Time Scale, which will energize the mode valve actuator 6a and initiate regeneration. After about twenty minutes and until the duct rotor has turned about 1 1/4 revolutions circuits 42a and 42b will be de-energized and the particulate trap will return to normal operation. Figs. 20A and 20B illustrate an embodiment of the remote actuated relief valve 10. The components consist of a section of exhaust pipe having a rectangular cross section 50, a rectangular butterfly valve with an off-center pivot shaft 51, a butterfly actuation lever 52, connecting link 53, an electromagnetic or pneumatic actuator 54, and an actuator ram member 55. The actuator ram member 55 contains a reciprocal slip link member 56, which is pressed to the left (in the drawing) to normally rest against a stop screw 57 by a low rate spring 58. When the actuator 54 is de-energized the actuator ram member 55 is spring loaded to the right (in the drawing) against a stop (spring and stop members not shown). When the control device determines the remote actuated relief valve 10 should be actuated, the electromagnetic actuator pushes the actuator ram 55 to the left (in the drawing) and remains in position against a stop member 54a. As a result of this action, the preloaded reciprocal slip link member 56 pushes the connecting link 53, which by way of butterfly actuation lever 52, and link 53 rotates the rectangular butterfly valve 51 to the closed position. This action immediately increases the pressure drop across the butterfly valve 51 and the pressure, acting on the unequal areas of the butterfly on each side of the pivot shaft, imparts a clockwise torque on the butterfly shaft. This torque is reflected by the linkages as force against the slip link member 56 (to the right in the drawing). When the pressure drop is 30 in. W.G. or greater, the force against slip link 56 will be great enough to overcome the preload of the low rate spring 58, and the slip link 56 will move to the right thus opening the rectangular butterfly valve 51. The spring rate of the low rate spring 58 coupled with the kinematics of the connecting links will be selected to assure that the pressure drop across the butterfly valve 51 will not exceed 40 or 50 in. W.G. It is emphasized that the amount of increased pressure P2 used for the reverse flow regeneration is not very critical. The pressure simply must be sufficient to dislodge and erode the soot and/or ash cake. The maximum pressure P2 is important only insofar as it affects engine performance during the regeneration events. Fig. 21 A illustrates an electro-mechanical remote actuated relief valve for use with cylindrical exhaust pipes that would be actuated by the control when it is desired to increase the pressure at the exit of the trap to at least 30 in. W.G. during the trap regeneration sequence. The remote actuated relief valve uses dual hemispherical butterfly valves 80 (Fig. 21C) in the cylindrical exhaust duct that sense and control the relief valve pressure drop. These are attached to small shafts 81 that pass through the support plate 82 that is welded to the exhaust duct 79 and terminate with control levers and attached linkage shown generally at 81a. Mounted on the support plate 82 is an actuator block 84 with its attached electromagnetic actuator 85. The actuator 85 contains a plunger 86 which is fitted in a bore in the actuator block 84 and whose total travel between its fully actuated position and its spring returned position is just enough to move the hemispherical butterfly valves 80 from fully closed against the inside of the duct 79 to fully open. The plunger contains a screw 86a and against its head a slip link 87that is held a preloaded low-rate spring 88. The screw 86 can be adjusted to vary the preloading of the spring as desired. The slip link 87moves reciprocally with the plunger 86 until the force against the slip link overcomes the spring preload. In assembly, the hemispherical butterfly valves 80 and their attached shafts 8 land linkages 81a are first installed. The actuator block 84 is then moved in place, the linkages 81a are attached to the slip link 87 as shown and the screws 89a used to mount the actuator block are loosely installed in the elongated slots 89. The actuator 85 is then energized and, while energized, the actuator block 84 is slid to the left (in the drawing) until the hemispherical valves are snugly seated in their fully closed position. The screws 89a are then tightened and the actuator 85 is de-energized. The plunger return spring, not shown, will then return the hemispherical valves to substantially their fully open position. The cover housing 90 will then be attached. In operation, when the relief valve is actuated the butterfly valves 80 will try to fully close. This will cause an increase in pressure ahead of the relief valve and the pressure, acting on the area of the butterfly valves 80, will create a clockwise torque on the upper butterfly valve and a counterclockwise torque on the lower butterfly valve. These forces will be transmitted through the shafts, levers and linkages and cause an axial force to the right on the slip link 87. The electromagnetic force on the plunger will hold the plunger 86 snugly against its stop in the energized position. Therefore, when the aforementioned forces are sufficient to overcome the preload of the spring 88 the slip link 87 will move to the right and the butterfly valves 80 will open to relieve the pressure. Obviously the valves will open more at high engine speed and load than they will at low speed and load. By keeping the spring rate of the preloaded spring 88 low and by alteration of the kinematics of the linkages 81a, the pressure level can be made to be reasonably constant over the various^' engine operating conditions. It should be noted that while the minimum relief valve pressure is very important, the variation above this pressure is primarily important to minimize engine backpressure to minimize any adverse affect on engine performance during the regeneration period. Figs. 22A and 22B illustrate a second embodiment of the remote actuated relief valve.

This configuration also uses a more conventional cylindrical length of exhaust pipe 60 and a substantially circular butterfly valve 61 in which the actuation shaft 62 passes through its center. The actuation shaft 62 is piloted on one end is bearing 62a. The other end of shaft 62 is piloted with close clearance at the wall 62b of the exhaust pipe and at 62c of a flat steel member 60a that is brazed or welded to the cylindrical exhaust pipe 60 to provide a support surface for the remote actuated relief valve assembly. The butterfly actuation shaft 62 continues on and passes through hole 64a in a stationary housing 64. The shaft 62 then enters the bellows diaphragm assembly shown generally at 63 which is located within the stationary housing 64. The shaft 62 terminates in a length 62d at which the shaft 62 has been machined to provide a rectangular cross section of 1/8 inch x 3/8 inch and which has been twisted through 90 degrees to form about a 3/4 inch long helical length, as shown. The helical length of butterfly shaft 62d engages with close clearance a 1/8 inch x 3/8 inch female rectangular slot 65a in the upper diaphragm plate 65. The upper diaphragm plate 65 is firmly attached with a hermetic seal to an upper end of a bellows diaphragm 66. In similar manner, a lower end of the bellows diaphragm 66 is firmly attached with a hermetic seal to a lower diaphragm plate 67. Pre-loaded (pre-compressed) low spring-rate calibration spring 68 is placed inside the bellows diaphragm 66 and piloted on both the upper diaphragm plate 65 and the lower diaphragm plate 67. The lower diaphragm plate 67 has an integral shaft 67a that passes with close clearance through passage 69a in the removable lower cover plate 69 for stationary housing 64. To permit any small leakage that passes between shaft 62d and slot 65a, the shaft 67a includes a small vent. The vent 67b also assures that the pressure within the bellows diaphragm assembly 63 remains at ambient pressure at all times. The portion of shaft 67a that passes out of the stationary housing 64 is attached to a rotary solenoid actuator 70 that is normally spring-loaded against a stop (not shown) but when energized will rotate through about 90 degrees before being arrested by another stop (not shown). In normal engine operation, the rotary solenoid actuator 70 will be spring-loaded against its stop. This action will have rotated the bellows diaphragm assembly 63, clockwise (viewed from the bottom) against a stop and placed the butterfly valve 61 in the wide open position, as shown. When the control system decides that remote actuated relief valve 10 should be actuated, the rotary solenoid will rotate the bellows diaphragm assembly 63 counter clockwise (viewed from the bottom) about 90 degrees and close the butterfly valve 61 completely. When this occurs, exhaust flow through the cylindrical exhaust pipe 60 will be prevented thus immediately increasing the pressure drop across the butterfly valve 61. This action will cause flow to occur through passage 60c from the exhaust pipe 60 and into a space 71 between the bellows diaphragm assembly 63 and the stationary housing 64. This flow will immediately begin to build up a pressure in the space 71 which will act to force upper diaphragm plate 65 down against the bellows and calibration spring 68. When this pressure has built up to about 30 in. W.G., the preload of the spring 68 and the bellows diaphragm 66 will be exceeded and the upper diaphragm plate 65 will move downward against the combined spring rate of the above members 65 and 68. This downward movement of the slot 65a against the helical configuration of length 62d will cause the butterfly shaft 62 to rotate clockwise (viewed from the bottom), thus opening the butterfly valve. This action will continue until the pressure upstream of the butterfly valve reaches about 40 in. W.G. Depending upon changes in the speed and load of the engine, the diaphragm assembly 63 will open or close continuously to keep the pressure within the above limits. It should be noted that there will be very little torque imparted to the butterfly shaft 62 due to pressure drop across the valve because the area of the butterfly valve are equal on each side of the shaft. When regeneration is completed and the control device signals that the particulate trap system should return to normal operation, the rotary solenoid 70 will be deactivated and the spring will rotate it clockwise against the stop and, by means of the bellows diaphragm assembly 63, again fully open the butterfly valve 61, and exhaust pressures will return to normal. It should be noted that the bellows diaphragm 66 and spring 68 have a very low spring rate when compressed axially. However, the bellows diaphragm 66 is very stiff in torsion. Figs. 23 A and 23B illustrate the particulate trap system 100 as installed on a highway vehicle 500. The vehicle 500 includes an exhaust system 510. As it can be seen, the exhaust system 510 and the particulate trap structure 1 are oriented in a generally vertical direction. It will be noted that the cyclone separator 8, soot igniter and ash receptacle 9 are independent of the particulate trap system structure 1. This is done to permit the cyclone separator 8 to be mounted parallel with the particulate trap structure 1 and to permit gravity to assist in the transfer of the separated soot and ash particles to the igniter and ash receptacle. In some embodiments, insulation is placed around the particulate trap structure 1 and the exhaust system 510 to keep the cyclone separator 8 warm to minimize condensation of water, as previously discussed. Fig. 24 illustrates, schematically, trap systems for use with large industrial, locomotive and marine engines. In these embodiments, the trap system may require two or more particulate traps. As it will be noted, the purge ducts have been connected to a common tube 80 leading to the cyclone separator and the soot igniter and ash receptacle (not shown in the depicted embodiment). Also, only one remote actuated relief valve 10 is employed. The dual trap system 200 includes trap structure 1, two particulate traps 2, two duct valve rotors 3, and two mode valve assemblies 6. As noted above, the present invention is very compact and can be installed in about any vehicle in which other wall-flow particulate trap systems are used. In addition, because the present invention does not have to be heated to effect regeneration, the present invention can be installed at any desired location in the vehicle exhaust system, such as the usual muffler location. Further, the present invention does not depend on the engine speed and/or load or entail any interaction with the engine control system. The present invention embodies a compact assembly. Finally, because the present invention uses continuous rotation and on off components, a very simple and dedicated control system can be employed and located at or near the particulate trap system. For these reasons, the single particulate trap embodiment is well suited to retrofit applications for a wide variety of vehicles, such as transit buses, school buses, automobiles and utility trucks. Similarly, the dual particulate trap system is well suited for retrofit applications for a wide variety of large engine applications which require more than one particulate trap, such as large trucks, locomotives, marine engines and industrial generators.

In a first method of retrofitting a vehicle having an exhaust system, the wall-flow particulate trap system is operatively connected to the vehicle's exhaust system. In a second method of retrofitting a vehicle, the exhaust system includes a muffler, the muffler is removed and replaced by the wall-flow particulate trap system. In yet a third method of retrofitting a vehicle, the exhaust system includes a muffler, the muffler is removed and replaced by the particulate trap system, and a muffler is operatively connected to the particulate trap system.

In this last method, the muffler may be the original muffler or a muffler of reduced size and/or capacity. In view of the foregoing, it will be seen that the several advantages of the invention are achieved and attained. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. As various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the invention, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be inteφreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.

Claims

What is Claimed Is:

1. A wall-flow particulate trap system comprising: a. at least one particulate trap having an inlet and an outlet, said at least one particulate trap disposed in an engine exhaust gas line; b. at least one mode valve assembly offset from said inlet of said at least one particulate trap; c. at least one remote actuated relief valve offset from said outlet of said at least one particulate trap; d. at least one duct rotor intermediate said at least one particulate trap and said at least one mode valve assembly, said at least one duct rotor having a first end and a second end, said second end of said at least one duct rotor in operative communication with said at least one mode valve assembly and at least a portion of said first end of said at least one duct rotor in fluid communication with said inlet of said at least one particulate trap; and e. at least one rotor drive in driving connection with said at least one duct rotor such that said portion of said first end in fluid communication with said inlet is changeable.

2. The system of claim 1, further comprising a layer of a heat expandable ceramic around said at least one particulate trap.

3. The system of claim 1, wherein said at least one mode valve assembly further comprises an actuator selected from the group consisting of a pneumatic actuator and an electric actuator.

4. The system of claim 1, wherein said at least one rotor drive further comprises an actuator selected from the group consisting of: a gear train, a worm gear and a ratchet.

5. The system of claim 1, wherein said fluid communication of said duct rotor with said at least one particulate trap is through a minor duct section.

6. The system of claim 5, wherein said minor duct section has a width of about 5 to about 30 degrees.

7. The system of claim 1, wherein said at least one particulate trap includes a cordierite cuff.

8. The system of claim 1, further comprising a seal for sealing said mode valve assembly to said at least one particulate trap.

9. The system of claim 1, further comprising a purge duct operatively connected to said at least one mode valve assembly.

10. The system of claim 9, further comprising a separator operatively connected to said purge duct.

11. The system of claim 10, further comprising an igniter and ash storage chamber operatively connected to said separator.

12. The system of claim 10 wherein said separator is a cyclone separator.

13. The system of claim 1, further comprising a control system operatively connected to said at least one mode valve assembly and to said at least one remote actuated relief valve.

14. The system of claim 13, wherein said control system comprises: a. a power input bus; b. a pulse generator electrically connected to signal said power bus to power operation of said mode valve assembly; c. a timer electrically connected to said pulse generator to time said signals.

15. The system of claim 13, wherein said control system further comprises: a pressure switch, said pressure switch being operatively connected to said controller to initiate action of said mode valve assembly upon a preconfigured pressure being sensed across said particulate trap.

16. The system of claim 9, further comprising an actuator operatively connected to said remote relief valve.

17. The system of claim 9 further comprising a spiral burner in fluid communication with said purge duct.

18. A wall-flow particulate trap system for an internal combustion engine, the internal combustion engine producing exhaust gas containing soot and ash, the wall-flow particulate trap system comprising: a. a trap structure having an exhaust gas inlet area and an exhaust gas outlet area; b. at least one purge duct operatively connected to said trap structure at said exhaust gas inlet area; c. at least one particulate trap adapted for mounting within said trap structure, said at least one particulate trap having an inlet and an outlet, said at least one particulate trap adapted to receive the engine exhaust gas and intermediate said exhaust gas inlet area and said exhaust gas outlet area; d. at least one mode valve assembly offset from said inlet of said at least one particulate trap and in fluid communication with said purge duct; e. at least one remote actuated relief valve offset from said outlet of said at least one particulate trap; f. at least one duct rotor having a first end and a second end, said second end of said at least one duct rotor operatively connected to said at least one purge duct, said at least one duct rotor including a minor duct section located at said first end, and said minor duct section in fluid communication with said inlet of said at least one particulate trap; g. at least one rotor drive in driving connection with said at least one duct rotor; and h. whereby, upon activation of said at least one remote actuated relief valve, said at least one particulate trap is regenerated by reverse flow of filtered exhaust gas through porous walls of a plurality of tubular passages.

19. The method of cleaning exhaust in an exhaust line comprising: placing a particulate trap in the exhaust line; disposing a duct in close cooperation with a portion of said particulate trap such that particles dislodged from said portion of said particulate trap enter said duct; reducing the pressure in said duct relative to a pressure on an opposite side of said particulate trap such that particles are dislodged from said portion of said particulate trap in close cooperation with said duct; and rotating said duct to vary said portion of said particulate trap in close cooperation with said duct.

20. The method of claim 17 wherein said step of reducing said pressure in said duct is initiated by a pressure differential across said particulate trap a preconfigured level.

21. The method of claim 17 wherein said step of reducing pressure in said duct to dislodge particles from said portion of said particulate trap heats the particles.

22. The method of claim 17 further comprising the step of burning said dislodged particles in a burner, said burner being in operative communication with said duct.

23. The method of claim 22 wherein said burning step is in a spiral burner.

24. The system of claim 1 wherein said rotor drive runs continuously at all times when the engine is running.

25. The system of claim 1 wherein said relief valve maintains pressure through said mode valve substantially at least 30 inches wg when operative.

26. The system of claim 1 wherein said mode valve allows downstream passage of exhaust in a non-regeneration stage and blocks downstream passage of exhaust during a regeneration state.

27. The method of claim 23 wherein said spiral burner has a centrifical heating element.

28. The system of claim 9 further comprising a spring, said spring biasing a face of said purge duct assembly against a face of said particulate trap.

29. The system of claim 1 further comprising a ring gear and a ratchet for driving said ring gear to actuate said rotor drive, said ring gear being outside a diameter of said particulate trap.

30. The system of claim 29 wherein said ring gear and said duct rotor are separate parts.

31. The system of claim 30 wherein said ring gear and duct rotor are laser welded together.

32. The system of claim 1 wherein said system includes a controller and an actuating sensor and wherein said system is a modular assembly separate from an engine of the vehicle in which the module is installed.

33. The controller of claim 1 wherein said rotor drive is continuously driven by a pulse generator, and a regeneration flow is controlled by a timer, said timer operating only during said regeneration flow.

34. The system of claim 33 wherein said timer is initiated by a pressure differential across said particulate trap, said pressure differential sensed by a pressure switch, and wherein said timer signals activation of an igniter and at least partial closure of said relief valve and wherein said timer opens said mode valve.

35. The system of claim 22 wherein said burning step is achieved by a partial elevation of temperature of burning particles by an exhaust flow.

36. The system of claim 1 wherein said relief valve maintains a substantially constant pressure during a regeneration.

37. The system of claim 36 wherein said relief valve is closed by a solenoid and maintained at a substantially constant pressure by a spring.

38. The system of claim 36 wherein said relief valve is closed electromechanically and a substantially constant pressure is maintained by a diaphragm and spring assembly.