Patent Publication Number: US-11035284-B2

Title: Pipe structure

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 USC 119 from Japanese Patent Application No. 2018-131084 filed Jul. 10, 2018, the disclosure of which is incorporated by reference herein in its entirety. 
     BACKGROUND 
     Technical Field 
     The present disclosure relates to a pipe structure. 
     Related Art 
     Since heretofore, the use of a catalyst in which iridium, neodymium and nickel are together carried on a carrier formed of silicon carbide to clean exhaust gas from an internal combustion engine of a car or the like has been known (for example, see Japanese Patent Application Laid-Open (JP-A) No. H8-71422). 
     SUMMARY 
     However, although this catalyst may clean exhaust gas, it may not remove hazardous components in air (such as ozone). 
     Accordingly, the present disclosure provides a pipe structure that may remove ozone from the air in a vicinity of a pipe. 
     In order to achieve the object described above, a pipe structure according to a first aspect of the present disclosure includes: a pipe disposed in a state of contact with the air, a fluid with a temperature of at least 100° C. flowing inside the pipe; and a coating material that contains nickel oxide and that is coated onto an outer periphery portion of the pipe. 
     According to the pipe structure of the first aspect, the nickel oxide, that is contained in the coating material coated onto the outer periphery portion of the pipe, is heated by the fluid with a temperature of 100° C. or more flowing inside the pipe that is disposed in a state of contact with the atmosphere. Consequently, ozone in the air in the vicinity of the pipe is removed by catalytic action of the nickel oxide. 
     In a pipe structure according to a second aspect of the present disclosure, in the pipe structure of the first aspect, a base material of the coating material is a porous material. 
     According to the pipe structure of the second aspect, the base material of the coating material is a porous material. Therefore, a contact surface area between the air and the nickel oxide is increased, and effectiveness of removal of ozone from the air in the vicinity of the pipe is improved. 
     In a pipe structure according to a third aspect of the present disclosure, in the pipe structure of the first aspect or the second aspect, the pipe is an exhaust pipe provided at a vehicle. 
     According to the pipe structure of the third aspect, the pipe serves as an exhaust pipe that is provided at a vehicle. Accordingly, ozone in the air in a vicinity of the exhaust pipe is removed during running of the vehicle. 
     In a pipe structure according to a fourth aspect of the present disclosure, in the pipe structure of the third aspect, the coating material is coated onto a surface of a sub-muffler that structures a portion of the exhaust pipe. 
     According to the pipe structure of the fourth aspect, the coating material is coated onto the surface of the sub-muffler that constitutes a portion of the exhaust pipe. This sub-muffler is a high-temperature region with a temperature of 100° C. or more. Therefore, the catalytic action of the nickel oxide is facilitated, and ozone in the air in the vicinity of the exhaust pipe is removed efficiently. 
     According to the pipe structure of the first aspect, ozone in the air in a vicinity of the pipe may be removed. 
     According to the pipe structure of the second aspect, the effectiveness of removal of the ozone in the air in the vicinity of the exhaust pipe may be improved. 
     According to the pipe structure of the third aspect, the ozone in the air in the vicinity of the exhaust pipe may be removed during running of the vehicle. 
     According to the pipe structure of the fourth aspect, the ozone in the air in the vicinity of the exhaust pipe may be removed efficiently. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view showing an exhaust pipe of a vehicle at which a pipe structure according to a present exemplary embodiment is employed; and 
         FIG. 2  is a graph showing a comparison of ozone concentrations over time between a vicinity of the exhaust pipe at which the pipe structure according to the present exemplary embodiment is employed and a vicinity of an exhaust pipe at which the pipe structure is not employed. 
     
    
    
     DETAILED DESCRIPTION 
     Herebelow, an exemplary embodiment of the present disclosure is described in detail in accordance with the drawings. 
     A pipe structure  10  according to the present exemplary embodiment can be excellently employed at an exhaust pipe  14  (of a vehicle), which serves as an example of a pipe  12 . Below, descriptions are given using the exhaust pipe  14  of the vehicle as an example. For convenience of description, the arrow UP shown in  FIG. 1  indicates a vehicle upper direction and the arrow FR indicates a vehicle front direction. 
     As shown in  FIG. 1 , the exhaust pipe  14  is provided at a lower portion of the vehicle (which is not shown in the drawings). The exhaust pipe  14  extends toward the vehicle rear side from an engine (not shown in the drawings) disposed at the vehicle front side. The exhaust pipe  14  is disposed in a state of contact with the atmosphere. A muffler  16  that constitutes a portion of the exhaust pipe  14  is connected in fluid communication with a rear end portion of the exhaust pipe  14 . 
     In a side view seen in the vehicle width direction, the muffler  16  is formed in a substantially elliptical shape with an axial direction in the vehicle width direction. The rear end portion of the exhaust pipe  14  is connected in fluid communication with a substantially central portion in the vehicle width direction of a front end portion of the muffler  16 . A muffler cutter  17  extends toward the vehicle body rear side from a right side portion of the muffler  16 . 
     A sub-muffler  18  that constitutes another portion of the exhaust pipe  14  is connected in fluid communication at an intermediate portion of the exhaust pipe  14 . The sub-muffler  18  is a two-layer tube structure formed with a larger diameter than other regions of the exhaust pipe  14 . The sub-muffler  18  acts as a high-temperature region inside which exhaust gases flow as a fluid with a temperature of 100° C. or more. 
     A coating material  20  containing nickel oxide is coated onto a surface (a whole outer periphery face)  18 A of the sub-muffler  18 . Nickel oxide is an inorganic compound that functions as a catalyst that decomposes and removes ozone when heated to 100° C. or more. In some embodiments, a base material (a material that serves as a base containing the nickel oxide) of the coating material  20  is a porous material. 
     Now, operations of the pipe member  10  structured as described above are described. 
     As described above, the coating material  20  containing nickel oxide is coated onto the surface  18 A of the sub-muffler  18 . Hence, during running of the vehicle, the surface  18 A of the sub-muffler  18  is heated by exhaust gas with a temperature of 100° C. or more flowing inside the sub-muffler  18 . Thus, the nickel oxide is heated by the exhaust gas with a temperature of 100° C. or more. Consequently, during running of the vehicle, ozone in the air in the vicinity of the sub-muffler  18  (the exhaust pipe  14 ) may be decomposed and removed by the catalytic action of the nickel oxide. 
     Test results are shown in  FIG. 2 . The graph depicted as a broken line in  FIG. 2  represents a situation in which the coating material  20  is not coated onto the sub-muffler  18 . The graph depicted as a solid line in  FIG. 2  represents a situation in which the coating material  20  is coated onto the sub-muffler  18 . Natural decomposition of ozone is facilitated by heating. Consequently, as shown by the broken line in  FIG. 2 , even when the coating material  20  (nickel oxide) has not been coated, ozone in the air in the vicinity of the sub-muffler  18  (the exhaust pipe  14 ) naturally decomposes and is removed as time passes (as around 600 seconds passes). 
     However, as shown by the solid line in  FIG. 2 , when the coating material  20  (nickel oxide) has been coated onto the sub-muffler  18 , ozone in the air in the vicinity of the sub-muffler  18  (the exhaust pipe  14 ) may be decomposed and removed in a shorter time, around 100 seconds, which is about six times faster than in the situation in which the coating material  20  (nickel oxide) has not been coated onto the sub-muffler  18 . In particular, if the base material of the coating material  20  is a porous material, because a contact surface area between the nickel oxide and the air is increased, the effectiveness of removal of ozone from the air in the vicinity of the sub-muffler  18  (the exhaust pipe  14 ) may be improved. 
     As described above, the sub-muffler  18  acts as a high-temperature region with a temperature of 100° C. or more. Therefore, when the coating material  20  (nickel oxide) is coated onto the sub-muffler  18 , the catalytic action of the nickel oxide may be facilitated compared to a situation in which the coating material  20  (nickel oxide) is coated onto a region of the exhaust pipe  14  other than the sub-muffler  18 . Thus, ozone in the air in the vicinity of the sub-muffler  18  (the exhaust pipe  14 ) may be removed efficiently. 
     Hereabove, the pipe structure  10  according to the present exemplary embodiment has been described in accordance with the attached drawings. However, the pipe structure  10  according to the present exemplary embodiment is not limited to the illustrated structure; suitable design modifications may be applied within a scope not departing from the scope of the present disclosure. For example, a region onto which the coating material  20  containing nickel oxide is coated is not limited to the sub-muffler  18  and may be an alternative region of the exhaust pipe  14 , although removing ozone efficiently may then be more difficult. 
     Further, the base material of the coating material  20  is not limited to porous materials. Further still, the pipe structure  10  according to the present exemplary embodiment is not limited to a structure that is employed at the exhaust pipe  14  (the sub-muffler  18 ) of a vehicle. The pipe structure  10  according to the present exemplary embodiment may be employed at any pipe  12 , provided a high-temperature fluid with a temperature of 100° C. or more flows in the pipe  12  and provided a region onto which the coating material  20  may be coated is formed at an outer periphery portion of the pipe  12 .