Abstract:
An engine enclosure ( 100, 200 ) for an agricultural work vehicle has a plurality of walls ( 114, 210, 216, 218, 230 ) that surround an internal combustion engine ( 102, 202 ) and a fan ( 122, 236 ) coupled to an air inlet ( 120, 238 ) in the plurality of walls for maintaining the inside of the engine enclosure ( 100, 200 ) at a pressure slightly higher than atmospheric pressure.

Description:
FIELD 
       [0001]    The field is work vehicles. More particularly, the field is engines and engine compartments for agricultural work vehicles. 
       BACKGROUND 
       [0002]    Agricultural work vehicles travel through agricultural fields planting, cultivating, treating and harvesting crops. These vehicles are often surrounded by clouds of light combustible matter, such as leaves, dust, chaff, and the like. 
         [0003]    This light combustible matter will accumulate in areas with stagnant air flow, often settling out and coating surfaces of high temperature objects such as exhaust pipes, turbochargers, diesel particulate filters, and the like. It is a concern that this accumulated light material will combust when otherwise cool surfaces are periodically cycled to extremely hot temperatures, such as a diesel particulate filter experiences during its regeneration process. 
         [0004]    There are many prior art arrangements that enclose an engine block and associated components. These can be seen in U.S. Pat. No. 4,324,208, U.S. Pat. No. 4,610,326, U.S. Pat. No. 4,891,940, U.S. Pat. No. 7,523,726, U.S. Pat. No. 2,250,382, U.S. Pat. No. 4,241,702, U.S. Pat. No. 3,949,726, and GB 1,397,476. 
         [0005]    These arrangements, however, are not directed to the problem of solving the accumulation of light combustible particles on exhaust gas aftertreatment devices such as diesel particulate filters. Instead, they are directed to ways of soundproofing engines, air cooling engines, cooling of mufflers, and the like. 
         [0006]    Some prior art arrangements are directed to the problem of combustible particles accumulating on diesel particulate filters or other hot exhaust gas conduits. These have proposed directing a flow of air (both clean and dirty) either continuously or intermittently across surfaces on which the particles may accumulate to either prevent the accumulation of light combustible particles or to periodically blow the light combustible particles off the surfaces. These prior art arrangements use the kinetic energy of air and therefore require nozzles located close to all of the surfaces on which particles might accumulate and a relatively large fan to supply air at a sufficient velocity. 
         [0007]    Both of these cleaning arrangements do not prevent light combustible materials from reaching the hot surfaces. Instead they deflect the light combustible material before it settles, or blow it off the surfaces before the surfaces are heated up sufficient to ignite the light particles. 
         [0008]    These cleaning arrangements are typically employed in vehicles in which a large volume of air is directed through an engine coolant heat exchanger and then through the engine compartment, across the surface of the engine and the other hot surfaces. Engine coolant heat exchangers typically require a large supply of air passing therethrough to extract sufficient heat from the engine coolant. 
         [0009]    A further problem with these cleaning arrangements is that so much air must pass through the engine coolant heat exchangers in order for them to work that it is impossible to filter the air sufficiently to remove all of the light combustible material. Much of the light combustible material is dust, and therefore would require filtering at a micron level in order to prevent its accumulation on surfaces inside the engine compartment. 
         [0010]    What is needed, therefore, is an improved method for preventing light combustible matter from accumulating on hot surfaces in the engine enclosure of an agricultural vehicle. What is also needed is a method that will not require extremely fine filtering of large quantities of engine cooling air and the attendant cleaning and replacement of filter elements. 
         [0011]    It is an object of this invention to provide such a system. 
       SUMMARY 
       [0012]    In one arrangement, a vehicle configured to work in an agricultural field has an internal combustion engine that is disposed inside an engine enclosure in the form of a box. The engine enclosure defines an air inlet. A source of air is coupled to the air inlet and generates an air flow into the engine enclosure. The source of air produces a slight positive pressure in the engine enclosure. The source of air maintains the air pressure in the engine enclosure slightly higher than the air pressure of the ambient environment surrounding the engine enclosure. The pressure produced by the source of air prevents dust and debris from entering the engine enclosure. 
         [0013]    In another arrangement, an engine enclosure for an internal combustion engine is provided that comprises a plurality of walls surrounding the internal combustion engine, wherein the walls define an air inlet opening into a space between the internal combustion engine and the plurality of walls, and the fan coupled to the air inlet to provide air under pressure to the space between the internal combustion engine and the plurality of walls, and to maintain the air in the space at a pressure above the air pressure outside the plurality of walls. 
         [0014]    The engine enclosure may further comprise a combustion air conduit coupled to the internal combustion engine to supply the internal combustion engine with air for internal combustion, wherein at least a portion of said combustion air conduit is disposed inside the engine enclosure. 
         [0015]    The combustion air conduit may extend through a wall of the plurality of walls. 
         [0016]    An end of the combustion air conduit may be disposed outside of the engine enclosure to receive ambient air from the environment outside of the engine enclosure and to conduct the ambient air through the wall of the plurality of walls and into the internal combustion engine. 
         [0017]    The fan may be disposed to receive ambient air from outside the engine enclosure and to convey the ambient air into the air inlet. 
         [0018]    An air filter may be disposed between the fan and the ambient environment to filter ambient air before it is conveyed into the air inlet. 
         [0019]    The engine enclosure may further comprise a heat exchanger disposed outside of the engine enclosure, and configured to receive ambient air from the ambient environment outside of the engine compartment, to transfer heat to the ambient air and to transmit now-heated ambient air back into the ambient environment outside of the engine compartment. 
         [0020]    The engine enclosure may further comprise a first engine coolant conduit coupled to and extending between the internal combustion engine and the heat exchanger to conduct hot engine coolant from the engine to the heat exchanger for cooling, and a second engine coolant conduit coupled to and extending between the internal combustion engine and the heat exchanger to conduct engine coolant from the heat exchanger back to the engine after cooling. 
         [0021]    The first engine coolant conduit and the second engine coolant conduit may extend through a wall of the engine enclosure. 
         [0022]    The engine enclosure may further comprise a PTO gearbox disposed inside the plurality of walls that is coupled to the internal combustion engine to be driven thereby. 
         [0023]    The engine enclosure may further comprise an output driveshaft coupled to and driven by the PTO gearbox. 
         [0024]    The output driveshaft may extend through a wall of the plurality of walls. 
         [0025]    The output driveshaft may be coupled to and may drive a driven machine disposed outside of the plurality of walls. 
         [0026]    The engine enclosure may further comprise an air vent extending from a wall of the plurality of walls and configured to communicate air from inside the engine enclosure to the ambient atmosphere outside of the engine enclosure thereby preventing overpressure of the engine enclosure. 
         [0027]    The plurality of walls may enclose a turbocharger that is coupled to the engine to pressurize combustion air for the engine. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0028]      FIG. 1  is a schematic diagram of an engine enclosure in accordance with the present invention. 
           [0029]      FIG. 2  is a schematic diagram of an alternative engine enclosure in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    Referring to  FIG. 1 , an engine enclosure  100  surrounds an internal combustion engine  102  that is coupled to a gearbox  104 . A turbocharger  106  is driven by exhaust gas leaving an exhaust manifold  108  of the internal combustion engine  102 . The exhaust gas passes through an exhaust gas aftertreatment device  110  and thence through a conduit  112  that passes through a wall  114  of the engine enclosure  100 . Turbocharger  106  sucks air into a combustion air conduit  116 , pressurizes it, and transmits it through a combustion air outlet  118  into the internal combustion engine  102 . An air inlet  120  is provided in a wall of the engine enclosure  100  to receive air pressurized by a fan  122 . Fan  122  has an air inlet that is coupled to and receives air from an air filter  124 . The air filter  124  is coupled to and receives air from a cyclone separator  126 . The cyclone separator  126  has a debris outlet  128  that receives debris, dust, and other solid particles from the cyclone separator  126 . The cyclone separator  126  has an intake air inlet  130  that receives air from the ambient atmosphere. An air vent  132  is provided in a wall of the engine enclosure  100  to permit excess air inside the engine enclosure  100  to escape the engine enclosure  100  thereby preventing overpressure of the engine enclosure  100 . 
         [0031]    Referring to an alternative arrangement shown in  FIG. 2 , an engine enclosure  200  surrounds an internal combustion engine  202  that is coupled to a gearbox  204 . An exhaust gas aftertreatment device  206  is coupled to internal combustion engine  202  to receive exhaust gas therefrom. The exhaust gas aftertreatment device  206  is internally configured to treat the exhaust gas to reduce the atmospheric contaminants entrained therein. A typical exhaust gas aftertreatment device  206  is a diesel particulate filter, which cycles from cool to extremely hot when it is regenerated. An exhaust gas outlet  208  extends from the exhaust gas aftertreatment device  206  through a wall  210  of the engine enclosure  200 . Aperture  212  and aperture  214  are provided in wall  216  and wall  218 , respectively, of the engine enclosure  200 . Aperture  212  and aperture  214  surround output drive shaft  220  and output drive shaft  222 , respectively. The output drive shaft  220  and the output drive shaft  222  extend from the gearbox  204 . The output drive shaft  220  and the output drive shaft  222  extend through the wall  216  and the wall  218  and are coupled to the driven machine  224  and the driven machine  226 , respectively to communicate power from the gearbox  204  to the driven machine  224  and the driven machine  226 . The driven machine  224  and the driven machine  226  are disposed outside of the engine enclosure  200 . A combustion air conduit  228  for the internal combustion engine  202  extends through a wall  230  of engine enclosure  200 . The combustion air conduit  228  is coupled to and receives air from and air filter  232  that is disposed outside of the engine enclosure  200 . The air filter  232  has an air inlet  234  that receives air from the ambient environment outside the engine enclosure  200 . A fan  236  is coupled to an air inlet  238  disposed in the wall  210  of the engine enclosure  200 . The fan  236  is disposed outside of the engine enclosure  200 . The inlet of the fan  236  is connected to an air filter  240 . The air filter  240  has an air inlet  242  that is open to receive air from the ambient environment outside the engine enclosure  200 . 
         [0032]    A first engine coolant conduit  244  is coupled to the internal combustion engine  202  to receive hot engine coolant therefrom and to conduct the hot engine coolant from the internal combustion engine  202  through the wall  210  of the engine enclosure  200 , and to a heat exchanger  246  for cooling engine coolant. A fan  248  is driven by a motor  250  and is disposed to move ambient air  254  through the heat exchanger  246  thereby cooling the hot engine coolant. The now-cool engine coolant is conveyed from the heat exchanger  246  into a second engine coolant conduit  252  which is coupled to the heat exchanger  246 . The second engine coolant conduit  252  is disposed to convey the cool engine coolant back to the internal combustion engine  202 . The second engine coolant conduit  252  passes through the wall  210  of the engine enclosure  200 . As in the example of  FIG. 1 , an air vent  256  is provided in the wall  218  of the engine enclosure  200  to permit excess air inside the engine enclosure  200  to be released into the ambient environment, thereby preventing overpressure of the engine enclosure  200 . 
         [0033]    The heat exchanger  246  is disposed outside of the engine enclosure  200  such that the ambient air  254  is drawn from the ambient environment surrounding the engine enclosure  200 , passes through the heat exchanger  246 , and is returned to the ambient environment surrounding the engine enclosure  200  without passing into or out of the engine enclosure  200 . In this way, the large quantities of air necessary for cooling the hot engine coolant need not be filtered in order to remove the large quantities of debris as is necessary in the traditional arrangement. In the traditional arrangement, as described above, air passing through the heat exchanger  246  for cooling engine coolant is then passed over and around the engine and other hot surfaces such as surfaces of the internal combustion engine  202 , the exhaust gas aftertreatment device  206 , and the exhaust gas outlet  208 .