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
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
  • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
  • F02B37/12—Control of the pumps
  • F02B37/18—Control of the pumps by bypassing exhaust from the inlet to the outlet of turbine or to the atmosphere
  • F02B37/183—Arrangements of bypass valves or actuators therefor
  • F02B37/186—Arrangements of actuators or linkage for bypass valves
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D17/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
  • F02C7/00—Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants
  • F02C7/28—Arrangement of seals
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2220/00—Application
  • F05D2220/40—Application in turbochargers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/12—Improving ICE efficiencies

Definitions

• This invention concerns an improved seal for a shaft which passes through, e.g., the turbine housing of a turbocharger, and the turbocharger having such a seal.
• Turbochargers are a type of forced induction system. They deliver air, at greater density than would be possible in the normally aspirated configuration, to the engine intake, allowing more fuel to be combusted, thus boosting the engine's horsepower without significantly increasing engine weight.
• a smaller turbocharged engine, replacing a normally aspirated engine of a larger physical size, will reduce the mass and can reduce the aerodynamic frontal area of the vehicle.
• Turbochargers use the exhaust flow from the engine exhaust manifold to drive a turbine wheel (21), which is located in the turbine housing (2). Once the exhaust gas has passed through the turbine wheel, and the turbine wheel has extracted energy from the exhaust gas, the spent exhaust gas exits the turbine housing and is ducted to the vehicle downpipe and usually to after-treatment devices such as catalytic converters, particulate traps, and NO x traps.
• after-treatment devices such as catalytic converters, particulate traps, and NO x traps.
• the turbine volute is fluidly connected to the turbine exducer by a bypass duct.
• Flow through the bypass duct is controlled by a wastegate valve (61). Because the inlet of the bypass duct is on the inlet side of the volute, which is upstream of the turbine wheel, and the outlet of the bypass duct is on the exducer side of the volute, which is downstream of the turbine wheel, flow through the bypass duct, when in the bypass mode, bypasses the turbine wheel, thus not powering the turbine wheel.
• an actuating or control force must be transmitted from outside the turbine housing, through the turbine housing, to the wastegate valve inside the turbine housing.
• a wastegate pivot shaft may extend through the turbine housing.
• an actuator (73) is connected to a wastegate arm (62) via a linkage (74), and the wastegate arm (62) is connected to the wastegate pivot shaft (63).
• the pivot shaft (63) is connected to the wastegate valve (61). Actuating force from the actuator is translated into rotation of the pivot shaft (63), pivoting the wastegate valve (61) inside the turbine housing.
• the wastegate pivot shaft rotates in a cylindrical bushing (68), or directly contacts the turbine housing. Because an annular gap exists between the shaft and the bore of the bushing, in which the shaft is located, an escape of hot, toxic exhaust gas and soot from the pressurized turbine housing is possible through this clearance.
• Turbine housings experience great temperature flux.
• the outside of the turbine housing faces ambient air temperature while the volute surfaces contact exhaust gases ranging from 740°C to 1050°C, depending on the fuel used in the engine.
• the temperature around the wastegate pivot shaft is around 400°C to 450°C. It is essential that the actuator, via the translated motions described above, be able to control the wastegate to thereby control flow to the turbine wheel in an accurate, repeatable, non- jamming manner.
• a VTG is used not only to control the flow of exhaust gas to the turbine wheel but also to control the turbine back pressure required to drive EGR exhaust gas, against a pressure gradient, into the compressor system to be re-admitted into the combustion chamber.
• the back-pressure within the turbine system can be in the region of up to 500kPa.
• High pressure inside the turbine stage can result in the escape of exhaust gas to the atmosphere through any apertures or gaps. Passage of the exhaust gas through these apertures is usually accompanied by black soot residue on the exit side of the gas escape path. Deposits of this soot, generated by the engine combustion process, is unwanted from a cosmetic standpoint. This makes exhaust leaks a particularly sensitive concern in vehicles such as ambulances and buses.
• the soot which escapes from the turbine stage is not captured and treated by the engine/vehicle aftertreatment systems.
• the test for the escape of particulate matter is to simply wrap the turbine stage in aluminum foil, run the engine for a period of time, and visually inspect the foil for traces of soot which has escaped from the turbine stage of the turbocharger.
• the soot one sees coming from the exhaust stack of a Diesel engine is a mix of exhaust by-products in three basic phases: coarse phase, accumulation phase, and nuclei phase.
• Most of the particulate mass consists of carbonaceous agglomerates and associated adsorbed materials and is passed in the accumulation mode which has sizes in the 0.05 ⁇ to ⁇ . ⁇ diameter range.
• the nuclei phase particles are typically volatile organics and sulfur compounds which have sizes in the 0.005 ⁇ to 0.05 ⁇ diameter range. While the particles in the nuclei phase are the greatest in number, they are only about 20% of the mass.
• Particles in the coarse phase range from 0.1 ⁇ to 8 ⁇ and contribute another 5-20% to the particulate mass.
• Coarse phase particles are typically accumulated on the walls of combustion and exhaust vessels and then re-entrained in the exhaust flow.
• Seal means such as seal rings, sometimes also called piston rings, are commonly used within a turbocharger to create a seal between the static bearing housing and the dynamic rotating assembly (i.e., turbine wheel, compressor wheel, and shaft) to control the passage of oil and gas from the bearing housing to both compressor and turbine stages and vice versa.
• BorgWarner Inc. has had seal rings for this purpose in production since at least 1954 when the first turbochargers were mass produced.
• the relative rubbing speed between the seal ring cheek and the side wall of the seal ring groove is of the order of 149,225 mm/sec.
• Seal rings of the variety which are used as described above, are sometimes used as a sealing device for relatively slowly rotating shafts (as compared to the 150,000 RPM turbocharger rapidly rotating assembly seals). These slowly rotating shafts move in rotational speeds of the order of 15 RPM which equates to a relative rubbing speed of 7 to 8mm/sec.
• Seal rings as used in turbochargers, create a seal by contacting part of the side wall of the seal ring against one side wall of a seal ring groove and contacting the outside diameter of the seal ring against the inside diameter of the bore in which the shaft resides.
• the depth of the seal ring groove must be such that the ring can collapse in outside diameter (and thus effective circumference and inside diameter) so that the outside diameter of the seal ring can assume approximately the inner diameter of the bore in which it operates.
• FIG. 2A depicts a seal ring (80) in the naturally expanded condition, albeit assembled to the shaft by forcibly expanding the ring over the diameter of the shaft (63) and then allowing the ring to relax into the groove.
• a chamfer (69) compresses the ring until the outside diameter of the ring can slide in the inside diameter (70) of the bushing.
• the now-compressed ring seals against the inside diameter of the bushing at any axial position of the shaft.
• the seal ring (80) can axially reside at any axial position within the confines of the ring groove, the seal ring groove being defined as: the volume radially between the outside diameter of the shaft (63) and the diameter of the floor (82) of the seal ring groove and axially the distance between the inner (83) and outer (81) walls of the seal ring groove.
• the seal ring groove being defined as: the volume radially between the outside diameter of the shaft (63) and the diameter of the floor (82) of the seal ring groove and axially the distance between the inner (83) and outer (81) walls of the seal ring groove.
• Fig. 3 depicts a condition in which the seal ring (80) is somewhat centered between the inner and outer walls (83 and 81) of the seal ring groove, thus allowing flow of gas and soot (86) around the seal ring. Since the axial position of the seal ring is controlled by the friction between the inner diameter of the bore in the bushing, and the ring is only moved by any contact with a side wall of a groove, a nearly complete sealing condition only exists when the seal ring sidewall is in direct contact with a seal ring groove side wall. In any other axial condition, the leakage path depicted in Fig. 3 exists, and gas and particulate matter can escape the turbine stage through the shaft area.
• the present invention solves the above problems by incorporating a semipermeable sealing media within the elements which constrain and support the rotating or sliding shaft assemblies which pierce the wall of a turbocharger housing, thus minimizing the escape of potentially aesthetically compromising or potentially harmful soot or particulate matter.
• Fig. 1 depicts a section for a typical wastegate turbocharger
• Figs. 2A,B depict two sections showing seal ring compression
• Fig. 3 depicts a section view showing gas leakage passage
• Fig. 4 depicts a section view of the first embodiment of the invention
• Fig. 5 depicts a section view of a variation to the first embodiment of the invention.
• Fig. 6 depicts a view of the second embodiment of the invention.
• Seal rings of the variety which are used as described above, are sometimes used as a sealing device for relatively slowly rotating shafts (as compared to the 150,000 RPM turbocharger rotating assembly seals). These slowly rotating shafts move in rotational speeds of the order of 15 RPM which equates to a relative rubbing speed of 7 to 8mm/sec. Even with the seal means described above, on both fast and relatively slowly moving shafts, there can be small escape of gases, soot, and other particulate matter which can negatively impact the aesthetics of an engine compartment.
• the inventor would provide a seal which would be permeable to gas but non-permeable to the soot.
• a seal which would be permeable to gas but non-permeable to the soot.
• the definition of such a seal will be referred to as a gas-permeable-non-soot-permeable (GPNSP) seal.
• GNSP gas-permeable-non-soot-permeable
• annular volume of the bushing (68), at the (outer) valve arm (62) end of the bushing was provided by either widening the bushing internal diameter or, as shown in Fig. 4, narrowing the shaft diameter to allow space for the GPNSP media (34).
• the annular volume taken up by the GPNSP has an inside diameter close to that of the shaft against which it seals, an outside diameter contacting the bore in the bushing in which the GPNSP media is radially constrained, and a length to fill the "provided for" space. Gas is free to travel through the GPNSP, but particulate matter will travel up the aforementioned annular volume and be trapped in the GPNSP media.
• the GPNSP media is located as close as possible to the (inner) wastegate valve (61) end of the bushing (68).
• the full length of the bore (70) bushing (68) is used to control the position of the pivot shaft (63), and a counterbore or cylindrical extension (66) is provided in the valve arm (62) to retain a donut-like piece of GPNSP media (34).
• the seal to the turbine housing is provided by the contact of the GPNSP media (37) with the lower surface (67) of the valve arm (62) and the upper surface (65) of the end of the bushing (68).
• any material that can be used in a Diesel soot filter can be used as the seal material of the present invention.
• Catalysts used in regeneration of Diesel filters are not required in the present invention, but may provide some benefit in maintaining or prolonging the gas permeability of the seal.
• Preferred materials are materials that can withstand mechanical vibration.
• metal based materials such as steel wool and glass based materials such as fiberglass are preferred over ceramic based materials.
• the device within the turbine housing actuated by an actuating mechanism located outside the turbine housing is preferably a wastegate, wherein the shaft is a wastegate pivot shaft, wherein the actuator is connected to a wastegate arm and the wastegate arm is connected to the wastegate pivot shaft, and wherein the wastegate pivot shaft extends through the turbine housing and is connected to the wastegate valve.
• the wastegate arm (62) is preferably provided with a counterbore or cylindrical extension (66) to retain a donut-shaped piece of sealing material against the outside the turbine housing or the end of the bushing.
• the device within the turbine housing actuated by an actuating mechanism located outside the turbine housing is a variable turbine geometry (VTG) device comprising a unison ring for actuating vanes forming nozzle passages, wherein a VTG actuator is connected to an arm on the actuator shaft, and wherein the actuator shaft extends through the turbine housing or the bearing housing and is connected to a link arm connected to the unison ring.
• VTG variable turbine geometry
• the sealing material is preferably fiberglass woven into a fabric and compressed into an annular shape.
• the sealing material is preferably in the form of glass fiber, steel wool, or ceramic mesh.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Supercharger (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=47996294

Family Applications (1)

Country Status (6)

Cited By (7)

Families Citing this family (7)

Citations (4)

Family Cites Families (5)

• 2012
  • 2012-09-06 KR KR1020147009624A patent/KR20140066226A/ko not_active Application Discontinuation
  • 2012-09-06 DE DE112012003266.7T patent/DE112012003266T5/de not_active Withdrawn
  • 2012-09-06 CN CN201280043684.2A patent/CN103782010B/zh active Active
  • 2012-09-06 WO PCT/US2012/053837 patent/WO2013048687A1/en active Application Filing
  • 2012-09-06 JP JP2014531849A patent/JP2014530317A/ja active Pending
  • 2012-09-06 US US14/344,924 patent/US20140348643A1/en not_active Abandoned

Patent Citations (4)

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