Patent Publication Number: US-7716922-B2

Title: Diesel particulate filter (DPF) in-chassis cleaning method

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to apparatuses and methods for cleaning a diesel particulate filter while installed in the chassis of a motor vehicle. 
   2. Description of the Prior Art 
   Diesel engines are efficient, durable and economical. Diesel exhaust, however, can harm both the environment and people. To reduce this harm governments, such as the United States and the European Union, have proposed stricter diesel exhaust emission regulations. These environmental regulations require diesel engines to nearly meet the same pollution emission standards as gasoline engines. 
   One part of diesel exhaust includes diesel particulate material. Diesel particulate material is mainly carbon particles or soot. One way to remove soot from diesel exhaust is with diesel traps. The most widely used diesel trap is a diesel particulate filter which nearly completely filters the soot without hindering exhaust flow. As a layer of soot collects on the surfaces of the inlet channels of the filter, the lower permeability of the soot layer causes a pressure drop in the filter and a gradual rise in the back pressure of the filter against the engine. This phenomenon causes the engine to work harder, thus decreasing engine operating efficiency. Eventually, the pressure drop in the filter and decreased engine efficiency becomes unacceptable, and the filter must either be replaced or the accumulated diesel soot must be cleaned out. 
   The filter is cleaned of accumulated diesel soot by burning-off or oxidation of the diesel soot to carbon dioxide which is known as regeneration. Regeneration of an existing filter is superior to filter replacement, because no interruption for service is necessary. 
   In addition to capturing carbon soot, the filter also traps ash particles, such as metal oxides, that are carried by the exhaust gas. These particles are not combustible and, therefore, are not removed during regeneration. The filter must therefore be cleaned or discarded when the ash particles in the filter build up to high levels. 
   Cleaning ash from a diesel particulate filter is not easily accomplished with typical maintenance shop equipment. The use of shop air to blow out the ash particles does not lend itself to containment of the ash particles. The use of a wet/dry vacuum tool has limited effectiveness on smaller and deeply embedded particles. The use of water or solvents can be detrimental to the substrate and/or washcoat. 
   Several methods of cleaning the filter require the removal of the filter from the chassis and insertion into specialized equipment for cleaning. These methods expose the heavy filter to excessive handling which increases the potential for inadvertent damage to this expensive component. The equipment is also expensive to purchase for the service shop, which would make the cost of cleaning expensive for the motor vehicle owner. 
   Therefore, it would be advantageous to develop a method to quickly and easily clean the ash particles from the filter while still attached to the chassis. It would be further advantageous to clean the filter without using costly additional or specialized equipment. 
   SUMMARY OF THE INVENTION 
   According to the invention there is provided an economical way of cleaning the ash from a diesel particulate filter of a motor vehicle. The method of the invention cleans ash particles from the diesel particulate filter by producing a pressure wave and introducing the pressure wave into a housing containing the diesel particulate filter. The pressure wave dislodges ash particulates from the filter, which can then be removed from the filter using a suction device, such as a shop vacuum. 
   The method cleans the filter apparatus while the apparatus is still attached to a chassis of the motor vehicle and engine. The diesel particulate filter is disposed within a housing. A first conduit is in fluid communication with the engine and the housing and has a port. A second conduit is in fluid communication with the housing and can have a second port. An inflatable bladder is bladder located in one of the conduits and accessible through one of the ports. 
   Additional effects, features and advantages will be apparent in the written description that follows. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a side view of a motor vehicle with the filter apparatus and pressure wave generator of the invention; 
       FIG. 2  is a partial cross-sectional view of a first embodiment of a filter apparatus and pressure wave generator of the invention; 
       FIG. 3  is a partial cross-sectional view of a second embodiment of a filter apparatus and pressure wave generator of the invention; 
       FIG. 4  is a cross-sectional view of a third embodiment of a filter apparatus and pressure wave generator of the invention removed from the motor vehicle; and 
       FIG. 5  is a partial cross-sectional view of a fourth embodiment of a filter apparatus and pressure wave generator of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Turning to the Figures where like reference numerals refer to like structures, the present invention relates to a method and apparatus for cleaning ash from a diesel particulate filter  20  which can be used while the diesel particulate filter  20  still attached to the motor vehicle  11  or truck, such as to the chassis, or used after removal of the diesel particulate filter  20  and housing  22 . The filter apparatus  10  can be installed on the motor vehicle  11  is any configuration, such as vertically, horizontally or under the cab. 
   The engine  12  is in fluid communication with the filter apparatus  10  through entrance tubing  14  at the inlet side of the filter apparatus  10 . Treated exhaust flows from the filter apparatus  10  through exit tubing  16 , which can include a tailpipe, at the outlet side of the filter apparatus  10 . 
   As shown in  FIGS. 1 and 2 , the filter apparatus  10  has a housing  22  and a diesel particulate filter  20  disposed therein. The filter apparatus  10  may connect with a catalytic device  18  located between the engine  12  and the filter apparatus  10 . The housing  22  has a first conduit  24  in fluid communication with the entrance tubing  14 . The opposite second conduit  26  is in fluid communication with the exit tubing  16 . 
   The first conduit  24  has a first port  28 . An inflatable first bladder  30  is located within the first conduit  24  and is accessible through the first port  28 . When inflated by pumping gas or air through the stem  31 , the first bladder  30  closes off the housing from the catalytic device  18 . 
   Pressure waves can be generated at the exit tubing  16  or second conduit  26  and transmitted into the housing  22 . After inflating the bladder  30 , pulses of compressed gas can be directed through the exit tubing  16  or second conduit into the housing  22 . The pulses of compressed gas dislodge the ash particles from the diesel particulate filter  20 . An ash collecting apparatus  84 , such as a shop vacuum, can be inserted into the first port  28  to remove the dislodged ash particles. 
   A second port  32  can be located between the housing  22  and an exit opening  34  of the exit tubing  16 , such as within the second conduit  26 . An inflatable second bladder  36  is accessible through the second port  32 . When inflated, the second bladder  36  closes off the housing  22  from the outside environment. 
   Pressure waves are introduced between the exit opening  34  of the exit tubing  16  and the housing  22 . The pressure waves are generated from a gas line  38  introduced through the second port  32  after inflating the second bladder  36 . The gas line  38  connects to a remote pressure wave generator  86 , such as pulses of compressed gas from a tank or air compressor. A controller can control the amount, frequency and pressure of the gas pulsed into the filter apparatus  10 . For the pressure wave, the gas should be at a high pressure, for example, about 20 psi to about 150 psi. 
   Alternatively, additional heat can be added to the housing  22  from a heat source through the first port  28  or second port  32  (not shown). A heat gun, water heater element, or propane flame can add heat through the first port  28  or second port  32 . The additional heat augments the heat generated by the running engine. 
   Alternatively, pressure waves can be introduced by pressure wave generator  40  located between the housing  22  and the exit opening  34  of the exit tubing  16 . As shown in  FIGS. 3 and 4 , pressure wave generator  40 ,  70  uses a vessel  42  in fluid communication with a gas line  44  attached to a source of gas, such as an air compressor or a gas tank. A stopper  48 , such as a cap, plug, pipe cape  72  or inflatable bladder as shown in  FIG. 5 , closes the exit opening  50  of the second conduit  26  to form a chamber  47 , with the gas line  44  inserted through the stopper  48 . The stopper  48  can have a safety tether. 
   The vessel  42  can be located within the second conduit  26  after first disconnecting the exit tubing  16 . Alternatively, the vessel  42  can be inserted into the second conduit  26  from the exit tubing  16  or used in the exit tubing  16 . The vessel  42  is surrounded by a safety device  46 , such as a cage, screen or a shield. The vessel  42  should be made from a stiff polymer having a known bursting pressure, such as polyethylene. 
   A pressure wave is generated by pressurizing the vessel  42  with the gas until the vessel  42  fails and bursts. The pressure wave generated should be about 100 psi to about 300 psi. The safety device  46  should contain any vessel debris. The gas source should be a high pressure air source, such as compressed air, an air compressor or compressed nitrogen. Preferably, the first bladder  30  is inflated within the first conduit  24  to protect the catalytic device  18  from any pressure waves. 
     FIG. 4  shows pressure wave generator  70  attached to the second conduit  26  after removing the exit tubing  16 . The pressure wave generator  70  has a pipe cape  72  with a pass-through air fitting  74 . A chamber  78  is defined by a cylindrical wall  76  extending between the pipe cape  72  and a flange  80  connected to the housing  22 . A vessel  42  connects to a gas line  44  inserted through the pass-through air fitting  74 . A screen  90  is placed inside the chamber  78  between the vessel  42  and the flange  80 . 
     FIG. 5  shows pressure wave generator  52 . A stopper  49 , such as a cap, plug, pipe cape or inflatable bladder  54 , forms a chamber  68  after inserting into the exit opening  34 ,  50  between the outside and the housing  22  to close at least part of the exit tubing  16  or second conduit  26 . The bladder  54  surrounds a fuel line  56 , a gas line  58  and an electrical line  60 , all of which are threaded from the exit opening  34  of the exit tubing  16  or the exit opening  50  of the second conduit  26  after removing the exit tubing  16 . The fuel line  56  and gas line  58  can end in a nozzle  62 . The electrical line  60  extends between a controller  64  and an igniter  66 , such as a spark igniter or piezoelectric igniter, with the igniter  66  located at or near the nozzle  62 . 
   The controller  64  can include electronic controls for manual inputs or can be programmed for automatic control. The controller  64  can be in communication with pressure sensors located in the fuel line  56 , the gas line  58  and the exit tubing  16  or second conduit  26 . 
   The fuel can be any fuel that ignites such as propane or other aerosols and can be pressurized. The gas is an oxygen source, is preferably compressed and can be air. 
   A cycle of pressure wave generation starts after the bladder  54  shown in  FIG. 4  is inflated. Then, gas is added to the chamber  68  through gas line  58 . After oxygen in the chamber  68  reaches a desired level, fuel starts to flow through the fuel line  56  to the nozzle  62 . The fuel is ignited by the igniter  66  which causes an explosion. The explosion generates a pressure wave which passes through the second conduit  26  and into the housing  22 . Additional pressure waves can be generated by repeating the cycle. 
   The controller  64  can control the cycle by controlling the delivery of gas, fuel and ignition. After oxygen reaches a level between the bladder  54  and the housing  22 , the controller  64  can stop the flow of gas. The controller  64  can next start the fuel flow and ignite the igniter  66 . The controller  64  can switch on the ash collecting apparatus  84  for removing the ash particles after igniting the fuel. Once the pressure drops in the chamber  68  after the explosion, the controller  64  can restart the cycle. 
   The ports  28 ,  32  are normally plugged during normal operating conditions. When the diesel particulate filter needs cleaning, the plugs are removed from the ports to allow cleaning and inflation of the bladders. 
   The diesel particulate filter  20  and its housing  22  can also be removed from the vehicle and cleaned using the pressure waves. As shown in  FIG. 4 , the diesel particulate filter is removed and attached to pressure wave generator  70 . A filtering apparatus  88  is attached to the first conduit  24  to filter ash and debris during the cleaning. 
   The method of the invention has a number of advantages. By leaving the diesel particulate filter attached to the chassis, the filter handling requirement for this method is reduced and thus has a lower risk of damage to the filter. Yet if desired, the filter can be removed from the vehicle and cleaned using the method of the invention. 
   The method is economical. The equipment used to clean the diesel particulate filter is readily available in a service shop. 
   While the invention is shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.