Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
  • F01N13/00—Exhaust or silencing apparatus characterised by constructional features
  • F01N13/14—Exhaust or silencing apparatus characterised by constructional features having thermal insulation
  • F01N13/148—Multiple layers of insulating material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
  • B60R13/00—Elements for body-finishing, identifying, or decorating; Arrangements or adaptations for advertising purposes
  • B60R13/08—Insulating elements, e.g. for sound insulation

Definitions

• This invention relates generally to heat shield assemblies for vehicle exhaust systems.
• Vehicles with internal combustion engines typically include an exhaust system with a plurality of exhaust pipes, a catalytic converter, a muffler and (sometimes) a lurbocharger. All of these components operate most efficiently at high temperatures.
• the exhaust system typically is responsible for the oxidation of unbumed hydrocarbons in the exhaust gas from the combustion process.
• Typical heat shield assemblies are made substantially entirely of one or more insulating materials with very low thermal conductivities in order to directly insulate the exhaust components to maximizing the heat retained in the exhaust components to optimize the oxidation of unburned hydrocarbons in the exhaust gas from the combustion process.
• the heat shield assembly Tor an exhaust system of an internal combustion engine of a vehicle.
• the heat shield assembly includes an inner-most layer that is directly engagable with an exhaust component and is of a non-ceramic material with a first heat capacity and a first thermal conductivity.
• the heat shield assembly additionally includes an insulating layer that surrounds the inner-most layer and Is of a material that has a second heat capacity which is lower than the first heat capacity and has a second thermal conductivity which is lower than the first thermal conductivity.
• the heat shield assembly is advantageous because, due to the high heat capacity and thermal conductivity, heat is very efficiently conducted between the exhaust component and the inner-most layer. As such, when the internal combustion engine is cold started with all components at an ambient temperature, the exhaust pipe warms relatively slowly because some of the heat from exhaust gasses travelling through the exhaust pipe is transferred into the inner-most layer. This protects the exhaust pipe from stresses due to rapid temperature change that could damage the exhaust component. Additionally, the high heat capacity and thermal conductivity of the inner-most layer allows the inner-most layer to trap a large amount of heat during operation of the engine and to return that heat back to the exhaust pipe after the engine has stopped operating, thereby reducing the rate at which the exhaust component cools.
• the inner-most layer is made of two pieces.
• the insulating layer is made of two pieces.
• the heat shield assembly further includes an outer shell that surround the inner-most and insulating layers for protecting the inner-most and insulating layers.
• the outer shield is made of two pieces.
• the two pieces of the outer shell are joined together by a weld seam.
• the weld scam joins the two pieces of the outer shell together at radially extending Ranges on the pieces of the outer shell.
• the outer shell extends longitudinally past the inner-most and insulating layers in both longitudinal directions.
• the outer shell tapers radially inwardly for directly contacting the exhaust component.
• the exhaust assembly includes an exhaust component, such as an exhaust pipe, and a heat shield assembly which includes an inner-most layer and an insulating layer.
• the innermost layer is in direct engagement with the exhaust component and is made of a non-ceramk material which has a first heat capacity and a first thermal conductivity for receiving and retaining heat from the exhaust component during operation of the internal combustion engine and for transferring heat back to the exhaust component after operation of the internal combustion engine has stopped.
• the insulating layer surrounds the inner-most layer and is of a material that has a second heal capacity that is lower than the first heat capacity and has a second thermal conductivity which is lower than the first thermal conductivity for insulating the exhaust component and the inner-most layer from another vehicle component.
• Figure 1 is a perspective view of an exhaust component in the form of an exhaust pipe with an exemplary embodiment of a heat sink assembly encasing a portion of a longitudinal length of the exhaust pipe;
• Figure 2 is a sectional and perspective view of the exhaust pipe and the heat sink assembly
• Figure 3 is an exploded view of the exemplary embodiment heat sink assembly
• Figure 4 is a cross-sectional view of the exhaust pipe and the exemplary embodiment of the neat sink assembly taken through Line 4-4 of Figure 1;
• Figure 5 is a perspective view showing a seam welding process being employed to weld two pieces of an outer shell of the exemplary heat sink assembly together;
• Figure 6 is an enlarged view of one longitudinal end of the exemplary embodiment of the heat sink assembly around the exhaust pipe; and [0023]
• Figure 7 is a perspective view of a heat shield covering a turbo charger, a catalytic converter and a portion of an exhaust pipe in an exemplary vehicle exhaust assembly.
• an exhaust component including a heat shield assembly 20 for use in a vehicle with an internal combustion engine is generally shown in Figure 1.
• the exemplary exhaust component is an exhaust pipe 22 for conveying exhaust gasses from an exhaust manifold of the engine to the ambient air via a tail pipe.
• heat shield assembly 20 could be used in conjunction with other types of exhaust components, such as a catalytic converter, a turbocharger or a muffler.
• the exemplary embodiment of the heat shield assembly 20 includes three distinct and separately formed layers which all surround or encapsulate a portion of the length of the exhaust pipe 22.
• a first of the three layers is an inner-most layer 24 which is in direct, surface-to-surface contact with the exhaust pipe 22 for directly transferring heat through conduction between the exhaust pipe 22 and the inner-most layer 24.
• the inner-most layer 24 is made of a first material which has a first heat capacity (also known as specific heat) and a first thermal conductivity.
• the first heat capacity and the first thermal conductivity of the non-ceramic material are both relatively high. Due to the high heat capacity and thermal conductivity, heat is very efficiently conducted between the exhaust component and the inner-most layer 24. As such, when the internal combustion engine is cold started with all components at an ambient temperature, the exhaust pipe 22 warms relatively slowly because some of the heat from exhaust gasses travelling through the exhaust pipe 22 is transferred into the inner-most layer 24. This protects the exhaust pipe 22 from damage that could occur from heating up too rapidly.
• the high heat capacity and thermal conductivity of the inner* most layer 24 allows the inner-most layer 24 to return heat back to the exhaust pipe 22 after the engine has stopped operating to reduce the rate at which the exhaust component cools.
• this also has the effeel of keeping the exhaust pipe 22 closer to an optimal operating temperature for if the internal combustion engine begins operation again in a short period. For example, if a driver of the vehicle turns the engine off while he or she goes into a store, the exhaust pipe 22 will be closer to its optimal operating temperature when he or she restarts the engine. This may have the effect of reducing pollutants that are emitted by the exhaust system and also improving the performance of the engine during the time that exhaust pipe 22 would otherwise be warming up to its optimal operating temperature.
• the inner-most layer 24 may be made of a material that is solid at normal ambient temperatures and which is liquid at normal operating temperatures of the exhaust pipe 22 for storing energy in the form of latent heat. Alternately, the inner-most layer 24 could be of a material that is solid throughout the operating temperature range of the exhaust pipe 22.
• Preferred materials for the inner-most layer 24 include salt paraffin; salt hydrates (such as pyrophosphate hydrates or eutectic salt hydrate mixtures, salts or cutcclic salt mixtures); molten salts; metallic alloys; binary or ternary metallic compositions of Aluminum, Silicon, Copper, Magnesium or Nickel; and graphite compositions.
• the heat shield assembly 20 also includes an insulating layer 26 which surrounds or encapsulates the inner-most layer 24.
• the insulating layer 26 is made of a material that has a second heat capacity which is lower than the first heat capacity of the inner-most layer 24 and with a second thermal conductivity which is lower than the first thermal conductivity of the inner-most layer 24.
• the insulating layer 26 is may be made of high temperature insulation fiber-mats, wools, needle-mats, knit blankets or other composites or compositions of materials such as silica fiber, E-glass fiber, Alkaline Earth Silicate fibers, basalt fibers or other applicable high temperature resistant, low thermal conductivity insulation materials.
• the insulating layer 26 restricts the escape of heat from the innermost layer 24, thereby maximizing the transfer of heat between the exhaust pipe 22 and the inner-most layer 24 and also protecting other vehicle components from the heat emanating from the exhaust pipe 22.
• the heat shield assembly 20 additionally includes an outer shell 28 which is made of a different material than the inncr-mosl and insulating layers 24, 26 surrounds or encapsulates the insulating layer 26.
• the outer shell 28 may be made of any suitable material (such as metal or plastic) for protecting the exhaust pipe 22 and the inner-most and insulating layers 24, 26 from damage due to stones, water, dust, debris and other contaminants under a body of the vehicle.
• each of the inner-most layer 24, the insulating layer 26 and the outer shell 28 is made as two, generally half-cylindrically shaped pieces with diametrically spaced apart and longitudinally extending edges 30 and with interior surfaces that are curved.
• the interior surfaces of the pieces of the inner-most layer 24 are curved to match the curvature of the curvature of an outer surface of the tubular exhaust pipe 22.
• the two pieces of the inner-most layer 24 are brought into a nesting relationship with opposite sides of the exhaust pipe 22, and the longitudinally extending edges 30 are brought into contact with one another such that the inner-most layer 24 surrounds or encapsulates a portion of the exhaust pipe 22.
• the insulating layer 26 is joined with the inner-most layer 24 through a similar process to the above-described connection between the inner-most layer 24 and the exhaust pipe 22.
• the two pieces of the outer shell 28 are locked together to trap the innermost and insulating layers 24, 26.
• the exemplary pieces of the outer shell 28 have flanges 32a, 32b that extend both radially outwardly and longitudinally along the length of the outer shell 28.
• the Ranges 32a, 32b are deformed into a locking engagement with one another and then welded together to trap the inner-most and insulating layers 24, 26 around the exhaust pipe 22.
• the exemplary flanges 32a, 32b are welded together through seam welding by engaging opposite sides of the flanges 32a, 32b with a pair of electrically charged roller electrodes 34 and passing the length of the flanges 32a, 32b between the roller electrodes 34.
• the passage of current from one electrode 34, through the flanges 32 and to the other electrode 34 has the effect of heating portions of the flanges 32a, 32b to their melting point, thereby establishing a weld joint 36 (shown in Figure 4) between the flanges 32a, 32b upon cooling.
• Seam welding has been found to be a particularly cost effective means to establish a reliable connection around the inner-most and insulating layers 24, 26.
• the outer shell 28 extends longitudinal past the neighboring ends of the innermost and insulating layers 24, 26 and tapers radially inwardly to directly contact the exhaust pipe 22.
• the exemplary outer shell 28 is also mechanically deformed to establish a gas and fluid tight seal between the outer shell 28 and the exhaust pipe 22. Additionally, an adhesive or coating could be applied to establish the gas and fluid tight seals between the longitudinal ends of the outer shell 28 and the exhaust pipe 22.
• FIG. 7 shows the exemplary embodiment of the heat shield assembly 20 as installed over a plurality of components in an exemplary exhaust system for a vehicle.
• the heat shield assembly 20 surrounds a turbo charger, a catalytic converter and a portion of an exhaust pipe.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• General Engineering & Computer Science (AREA)
• Exhaust Silencers (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

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Family Applications (1)

Country Status (5)

Cited By (1)

Families Citing this family (5)

Citations (1)

Family Cites Families (25)

• 2015
  • 2015-12-27 US US14/979,416 patent/US9840959B2/en not_active Expired - Fee Related
• 2016
  • 2016-12-18 WO PCT/US2016/067406 patent/WO2017116777A1/en not_active Ceased
  • 2016-12-18 CN CN201680076317.0A patent/CN108602472A/zh active Pending
  • 2016-12-18 DE DE112016006076.9T patent/DE112016006076T5/de not_active Withdrawn
  • 2016-12-18 JP JP2018533806A patent/JP2019505715A/ja not_active Withdrawn

Patent Citations (1)

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