Patent Publication Number: US-2016230717-A1

Title: Coating for engine

Description:
TECHNICAL FIELD 
     The present disclosure relates to a coating for an engine. More particularly, the present disclosure relates to the coating for a passageway associated with the engine. 
     BACKGROUND 
     Generally, in cold climate, water vapor present in an intake air of an engine may condense on inner surface of an intake system such as an intake line and/or an intake manifold. Due to low surface temperature, the condensate may further freeze forming an ice layer on the inner surface of the intake system. After an extended period of time, formation of the ice layer may increase. As a result, the ice layer may block the intake system and restrict flow of intake air therethrough. This may lead to reduced volume of intake air reaching one or more cylinders of the engine. As a result, an amount of unburned hydrocarbon may increase in an exhaust air. This unburned hydrocarbon may further bum in components of an aftertreatment system of the engine leading to damage to the aftertreatment system. 
     Also, in some situations, the water vapor may condense on components of the intake system such as a pressure sensor, a temperature sensor, and so on, The condensate may form a layer over the sensors leading to erroneous signals generated by the sensors. 
     Additionally, mixers employed in the aftertreatment system of the engine receive a flow of the exhaust air and a reductant for reducing a droplet size of the reductant and homogenizing a mixture of the exhaust air and the reductant. Due to continuous use, the reductant may accumulate on surfaces of the mixer and form deposits. Over a period of time, the deposit may grow in size leading to blockage. As a result, the performance of the mixer may reduce due to improper mixing of the reductant which may increase tail pipe emissions. 
     U.S. Patent Application Number 2015/0211398 describes a vehicle exhaust system. The system includes a mixer having an inlet that receives engine exhaust gases and an outlet to direct swirling engine exhaust gas to a downstream exhaust component. The mixer includes a plurality of internal surfaces that come into contact with the engine exhaust gases. At least one of the internal surfaces includes a coating comprised of a low-coefficient of friction material. 
     Currently used surface coatings may not be efficient to limit deposit formation of the reductant on surfaces of the mixer or condensation of water vapor on inner surfaces of the intake system over a period of time. In some situations, the mixer and/or the intake system may include additional thermal devices to limit deposit formation and condensation respectively. Such thermal devices may add to an overall system cost, reduce system efficiency, increase system weight, and so on. Also, in some situations, in order to limit deposit formation on surfaces of the mixer, dosing of the reductant may be reduced in conditions favorable for deposit formation, such as low system temperature, reduced engine load, and so on. However, this may increase engine emissions and prevent the engine from being emission complaint. Hence, there is a need for an improved coating for the engine to limit deposit formation and/or condensation of the water vapor. 
     SUMMARY OF THE DISCLOSURE 
     In an aspect of the present disclosure, an engine system is provided. The engine system includes a passageway having an inner surface and an outer surface. The passageway is adapted to allow a flow of air therethrough. The engine system also includes a sensor provided in the passageway and in contact with the air. The sensor is adapted to sense a parameter of the air. The engine system further includes a hydrophobic coating having a micropatterned texture provided on at least one of the inner surface of the passageway and the sensor. The hydrophobic coating is adapted to limit deposition of at least one of a fluid and a solid thereon. 
     Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an engine system, according to one embodiment of the present disclosure; 
         FIG. 2  is a partial cutaway view of an air intake system, according to one embodiment of the present disclosure; 
         FIG. 3  is a perspective view of a mixer of an exhaust aftertreatment system, according to another embodiment of the present disclosure; and 
         FIG. 4  is a side sectional view of an exemplary surface coating, according to one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or the like parts. Referring to  FIG. 1 , a schematic diagram of an engine system  10  is illustrated. The engine system  10  includes an engine  12 . The engine  12  may include an internal combustion engine powered by any fuel known in the art such as gasoline, diesel, natural gas, and so on, or a combination thereof. The engine  12  may be used for applications including, but not limited to, power generation, transportation, construction, agriculture, forestry, aviation, marine, material handling, and waste management. 
     The engine system  10  includes an air intake system  14  fluidly coupled to the engine  12 . The air intake system  14  is adapted to provide a flow of an intake air into the engine  12 . Referring to  FIG. 2 , the air intake system  14  includes an intake line  16  having an inner surface  18  and an outer surface  20 . The air intake system  14  also includes an intake manifold  22  having an inner surface  24  and an outer surface  26 . The intake manifold  22  is fluidly coupled to the intake line  16 . The intake line  16  and the intake manifold  22  are adapted to provide a passageway for the flow of the intake air from atmosphere into the engine  12 . The air intake system  14  may also include an air filter (not shown) provided downstream of the intake line  16 . The air filter may be adapted to provide filtration of the intake air prior to flowing into the intake line  16  and the intake manifold  22 . 
     The air intake system  14  also includes one or more sensors such as a pressure sensor  28  and a temperature sensor  30 . In other embodiments, the sensors may, additionally or alternatively, include any other sensor such as a humidity sensor, a flow rate sensor, and so on based on application requirements. The sensors are adapted to determine a parameter of the intake air. More specifically, the pressure sensor  28  is adapted to determine a pressure of the intake air. The temperature sensor  30  is adapted to determine a temperature of the intake air. 
     In the illustrated embodiment, the pressure sensor  28  and the temperature sensor  30  are coupled to the intake manifold  22 . More specifically, the pressure sensor  28  and the temperature sensor  30  are provided in contact with the intake air. In other embodiments, the pressure sensor  28  and the temperature sensor  30  may, alternatively or additionally, be coupled to the intake line  16  based on application requirements and in contact with the intake air. 
     Referring to  FIG. 1 , the engine system  10  includes an exhaust aftertreatment system  32  fluidly coupled to the engine  12 . The exhaust aftertreatment system  32  is fluidly coupled to the engine  12  via an exhaust line  34  having an inner surface  36  and an outer surface  38 . The exhaust line  34  is adapted to provide a passageway for a flow of an exhaust air from the engine  12  to the exhaust aftertreatment system  32 . The exhaust aftertreatment system  32  is adapted to receive and treat the exhaust air generated by the engine  12 . The exhaust aftertreatment system  32  includes a Diesel Oxidation Catalyst (DOC)  40 . The DOC  40  is fluidly coupled to the engine  12  via the exhaust line  34 . The DOC  40  is adapted to oxidize one or more components of the exhaust air such as Carbon Monoxide (CO), Hydrocarbons (HC), and so on. 
     The exhaust aftertreatment system  32  includes a Diesel Particulate Filter (DPF)  42 . The DPF  42  is provided downstream of the DOC  40  and fluidly coupled to the DOC  40  via the exhaust line  34 . The DPF  42  is adapted to provide filtration of particulate matter present in the exhaust air, The exhaust aftertreatment system  32  includes an injection system  44 . The injection system  44  includes a reductant tank  46 . The reductant tank  46  is adapted to store and supply a reductant, such as a urea water solution, to the exhaust aftertreatment system  32 . The injection system  44  also includes an injector  48  (also shown in  FIG. 3 ). The injector  48  is fluidly coupled to the reductant tank  46 . The injector  48  is also fluidly coupled to the exhaust line  34  downstream of the DPF  42 . The injector  48  is adapted to inject the reductant from the reductant tank  46  into the exhaust line  34 . 
     Referring to  FIG. 3 , the exhaust aftertreatment system  32  also includes a mixer  50  having a surface  52 . The mixer  50  is provided within the exhaust line  34  and downstream of the injector  48 . The mixer  50  is adapted to provide mixing and homogenizing of a mixture of the exhaust air and the reductant. The mixer  50  may be any mixer known in the art such as an impact mixer, a swirl mixer, a combination mixer, a plate type mixer, a baffle type mixer, a rotary mixer, and so on. The exhaust aftertreatment system  32  further includes a Selective Catalytic Reduction (SCR) unit  54  provided downstream of the mixer  50  and fluidly coupled to the exhaust line  34 . The SCR unit  54  is adapted to reduce Nitrogen Oxides (NOx) present in the exhaust air with the reductant preferentially into Nitrogen (N 2 ), and water (H 2 O). 
     Referring to  FIG. 4 , the present disclosure relates to a hydrophobic coating  56  provided on at least one of an inner surface of a passageway and a sensor associated with the engine system  10 . More specifically, in the illustrated embodiment, the hydrophobic coating  56  is provided on the inner surface  24  of the intake manifold  22 . In other embodiments, the hydrophobic coating  56  may be provided on the inner surface  18  of the intake line  16 , the surface  52  of the mixer  50 , a surface  58  of the pressure sensor  28  in contact with the intake air, and/or a surface  60  of the temperature sensor  30  in contact with the intake air. in other embodiments, the hydrophobic coating  56  may, additionally or alternatively, be provided on other components of the engine system  10  and/or the exhaust aftertreatment system  32  such as a turbocharger inlet and/or outlet (not shown), a compressor inlet and/or outlet (not shown), a cylinder port (not shown), the inner surface  36  of the exhaust line  34 , and so on based on application requirements and without limiting the scope of the disclosure. 
     Further, the hydrophobic coating  56  also includes a micropatterned texture  62  formed thereon. The hydrophobic coating  56  and the micropatterned texture  62  are adapted to limit deposition of at least one of a fluid and a solid thereon. More specifically, the hydrophobic coating  56  limits adhesion between the fluid droplets and a base surface, such as the inner surface  24  of the intake manifold  22 , by increasing the contact angle between the fluid droplets and the hydrophobic coating  56 . As a result, wetting of the base surface by the fluid droplets is reduced which in turn limits deposition and solidification of the fluid droplets on the base surface. 
     For example, when the hydrophobic coating  56  with the micropatterned texture  62  is provided on the inner surface  24  of the intake manifold  22 , the inner surface  18  of the intake line  16 , the surface  58  of the pressure sensor  28 , and/or the surface  60  of the temperature sensor  30 , the hydrophobic coating  56  is adapted to limit condensation of water vapor present in the intake air on the inner surface  24  of the intake manifold  22 , the inner surface  18  of the intake line  16 , the surface  58  of the pressure sensor  28 , and/or the surface  60  of the temperature sensor  30  which when cooled further may form of ice. Similarly, when the hydrophobic coating  56  with the micropatterned texture  62  is provided on the surface  52  of the mixer  50 , the hydrophobic coating  56  is adapted to limit deposition of reductant droplets, such as the urea water solution, and/or solid particles, such as the particulate matter, which when cooled may solidify on the surface  52  of the mixer  50 . 
     The hydrophobic coating  56  with the micropatterned texture  62  may be made of any material having hydrophobic properties such as silica glass, grafted polymer, chrome nitride, graphene, TEFLON™ and so on. The micropatterned texture  62  may include any profile such as multiple dots, dimples, stripes, waves, peaks, valleys, crests, troughs, shapes such as triangles, circles, rectangles, and so on spaced apart from one another or a combination thereof. 
     Also, the hydrophobic coating  56  with the micropatterned texture  62  may be formed by any lithographic process known in the art such as chemical lithography, photolithography, and so on. In other embodiments, the hydrophobic coating  56  with the micropatterned texture  62  may be formed by any additive manufacturing process known in the art such as 3D printing and so on. In yet other embodiments, the complete component such as the intake manifold  22 , the intake line  16 , the pressure sensor  28 , the temperature sensor  30  and/or the mixer  50  may be 3D printed with the micropatterned texture  62 . 
     It should be noted that the hydrophobic coating  56  with the micropatterned texture  62  disclosed herein is merely exemplary. In some embodiments, the inner surface  24  of the intake manifold  22 , the inner surface  18  of the intake line  16 , the surface  58  of the pressure sensor  28 , the surface  60  of the temperature sensor  30 , and/or the surface  52  of the mixer  50  may include the micropatterned texture  62  directly on the base surface without the hydrophobic coating  56  based on application requirements. Also, a size of the micropatterned texture  62  may vary based on application requirements such that in some embodiments the micropatterned texture  62  may be fine enough to be classified as a nanopatterned texture. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure relates to the hydrophobic coating  56  with the micropatterned texture  62  provided on the surfaces of the components of the engine system  10 . In cold climates, the hydrophobic coating  56  provided on the inner surfaces  18 ,  24  of the intake line  16  and/or the intake manifold  22  respectively limits condensation of the water vapor present in the intake air and further ice formation on the inner surfaces  18 ,  24 . Similarly, the hydrophobic coating  56  provided on the surface  52  of the mixer  50  limits deposition and solidification of the urea droplets thereon. 
     The hydrophobic coating  56  provides reduction of wetting of the surface  52  of the mixer  50  by the reductant droplets. Additionally, the micropatterned texture  62  provides shearing of the reductant droplets/solid particles from the surface  52  of the mixer  50 , The sheared reductant droplets/solid particles are further carried away by the flow of the exhaust air prior to accumulating into larger droplets. The micropatterned texture  62  also provides reduction of heat transfer between the surface  52  of the mixer  50  and the reductant droplets due to the increased contact angle therebetween. The reduction of heat transfer provides reduction of cold spots on the surface  52  of the mixer  50 . As a result, the hydrophobic coating  56  with the micropatterned texture  62  provides reduction of accumulation of the reductant droplets and deposit formation on the mixer  50 . 
     Similarly, the hydrophobic coating  56  provides reduction of wetting of the inner surface  24  of the intake manifold  22 , the inner surface  18  of the intake line  16 , the surface  58  of the pressure sensor  28 , and/or the surface  60  of the temperature sensor  30  by the water droplets. Additionally, the micropatterned texture  62  provides shearing of the water droplets from the inner surface  24  of the intake manifold  22 , the inner surface  18  of the intake line  16 , the surface  58  of the pressure sensor  28 , and/or the surface  60  of the temperature sensor  30 . The sheared water droplets are further carried away by the flow of the intake air prior to accumulating into larger droplets. The micropatterned texture  62  also provides reduction of heat transfer between the inner surface  24  of the intake manifold  22 , the inner surface  18  of the intake line  16 , the surface  58  of the pressure sensor  28 , the surface  60  of the temperature sensor  30  and the water droplets due to the increased contact angle therebetween. The reduction of heat transfer provides reduction of cold spots on the inner surface  24  of the intake manifold  22 , the inner surface  18  of the intake line  16 , the surface  58  of the pressure sensor  28 , and/or the surface  60  of the temperature sensor  30 . As a result, the hydrophobic coating  56  with the micropatterned texture  62  provides reduction of accumulation of the water droplets and ice formation on the inner surface  24  of the intake manifold  22 , the inner surface  18  of the intake line  16 , the surface  58  of the pressure sensor  28 , and/or the surface  60  of the temperature sensor  30 . 
     The hydrophobic coating  56  with the micropatterned texture  62  provides an effective and cost efficient method to limit ice formation within the intake system  14  and/or urea deposition on the mixer  50 . The hydrophobic coating  56  with the micropatterned texture  62  may be provided on the surfaces of the components of the engine system  10  without adding considerable weight to the system and without making extensive modifications to the existing system design. 
     While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of the disclosure. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.