Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
  • F01D5/12—Blades
  • F01D5/28—Selecting particular materials; Particular measures relating thereto; Measures against erosion or corrosion
  • F01D5/284—Selection of ceramic materials
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
  • F01D5/02—Blade-carrying members, e.g. rotors
  • F01D5/04—Blade-carrying members, e.g. rotors for radial-flow machines or engines
  • F01D5/043—Blade-carrying members, e.g. rotors for radial-flow machines or engines of the axial inlet- radial outlet, or vice versa, type
  • F01D5/048—Form or construction

Definitions

• the invention relates to a ceramic turbine wheel, expecially a ceramic radial turbine wheel for an exhaust gas driven turbine of a turbocharger for motor vehicles, with a body which is formed in one piece with radial blades and a hub which is connectable to a usually metallic turbine shaft.
• Ceramic materials such as silicon nitride or silicon carbide, have a nearly constant high strength in the range of temperature under consideration, and have a density which is only one-third of that of a metallic material.
• the operating temperatures can be raised without danger, while the mass moment of inertia, due to the relative low density of the ceramic turbocharger rotor, can be reduced to about 40% of the moment of inertia of a metallic type rotor, and therefore, the time of response of the turbocharger correspondingly improves.
• the object of this invention is therefore construction of a ceramic turbine wheel, which, although it has a sufficient high temperature strength, does not show the above described difficulties in production.
• This invention accordingly, provides a ceramic turbine wheel, comprising: (a) a body portion, symmetrical about an axis;
• a hub portion integral and coaxial with the body portion, symmetrical about the axis, and connectable with a turbine shaft; characterized in that the body portion is provided with a hollow central core, on the side of the body portion opposite the hub portion.
• the portion of the turbine from which the blades extend outwardly will become more elastic, so that deformations of the blades can be taken up sooner without damage.
• ceramic materials e.g. silicon nitride and silicon carbide
• the design of the hub results in a further reduction of the mass moment of inertia, already lowered by the use of ceramic material.
• the drawing shows schematically a presentation of a cross section, according to the invention, of a preferred embodiment of a ceramic radial turbine wheel for the turbocharger of a combustion engine for a motor vehicle, in which the hub portion is cylindrical.
• the radial turbine wheel As a whole; by 2, the blades which extend outwardly, usually radially, from the body portion; and by 3 the body portion, which is formed in one piece with blades 2 and the hub portion 4.
• the hub portion 4 is provided for connection with a usually metallic, some-times ceramic turbine shaft, which is not shown here.
• the blades 2 are described as “radial”, i.e. not “axial”. In the turbocharger art, the two main types of blade arrangements are “radial” and “axial”. In the “radial” type, portions of the blades 2, near the hub portion 4, are located along radii of the body portion 3; and portions of the blades 2, further from the hub portion 4, are curved gently in the same direction.
• the body portion 3 has on the side opposite to the hub portion 4 a hollow central core 5, whose outer diameter, designated with D 5 , should preferably not exceed 60% of the smallest outer diameter, designated with D 3min , of the body portion 3; and whose length, designated with L 5 , should preferably not exceed 60% of the axial blade length, designed by L.
• L 5 extends only from the base of the hollow central core 5 to the extremity of the blades 2, and not to the extremity of the hollow central core 5.
• at least 40% of the blade length L should extend from a non-hollow part of body portion 3. With such proportions, no noticible increases in tension appear in the body portion 3.
• the hollow central core 5, rounded at its bottom could be placed even deeper, in consideration of expediency.
• the minimum outer diameter, D 3min , of the body portion 3, be at the side of the body portion 3 opposite to the hub portion 4, and that the maximum outer diameter, D 3max , of the body portion 3, be at the side of the body portion 3 adjacent to the hub portion 4, of the turbine wheel 1.
• the hub portion 4 preferably has a diameter D 4 of about 15 to 25%, more preferably 15 to 20%, of the outer diameter D of the wheel. According to one preference, the hub portion 4 has a length L 4 of, at most, twice its diameter D 4 . According to another preference, the hub portion 4 is integral with the shaft, not shown.
• the shaft can be either a solid or hollow cylinder, made as an extension of hub portion 4, ranging from about 6 up to about 12 times the diameter D 4 of the hub portion 4.
• the transition 7 from the hub portion 4 to the body portion 3 there should preferably be provided a radius of at least 20% of the diameter of the hub portion 4.
• a radius of at least 20% of the diameter of the hub portion 4. By adherence to these rules of dimension for the production out of ceramic materials an optimally designed radial turbine wheel results, which offers favorable properties regarding to its strength as well as regarding to its production process.
• the embodiment shown in the drawing has a cylindrical hub portion 4.
• the basic diameter measured at about 60% of its length, measured from its end corresponds to the diameter D 4 of the cylindrical design.
• the cone angle of this design can amount to between 20° and 30° inclusive, preferably about 25°.
• this conical hub portion in consideration of expediency, can possess a hollow central core, whose diameter is at most 60% of the minimum diameter of the conical hub portion and whose axial length is at most 60% of the length of the hub portion.
• the hollow central core is rounded at its bottom.
• the transition from the conical hub portion to the body is rounded with a radius of at least 20% of the diameter of the hub portion.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Turbine Rotor Nozzle Sealing (AREA)
• Supercharger (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=22154286

Family Applications (1)

Country Status (4)

Cited By (4)

Families Citing this family (1)

Citations (12)

Family Cites Families (2)

• 1980
  • 1980-04-17 JP JP56500658A patent/JPS57500745A/ja active Pending
  • 1980-04-17 AT AT81900346T patent/ATE14036T1/de not_active IP Right Cessation
  • 1980-04-17 WO PCT/US1980/000419 patent/WO1981003047A1/en active IP Right Grant
  • 1980-04-17 EP EP81900346A patent/EP0050117B1/en not_active Expired

Patent Citations (12)

Also Published As

Similar Documents

Legal Events