JPH0322489Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a ceramic turbine rotor for a turbocharger for an internal combustion engine, in which a metal shaft for connecting to a blade on the compressor side is joined to the turbine rotor made of ceramic material.

(Prior art) Since the exhaust-side turbine rotor of a turbocharger for an internal combustion engine is exposed to high-temperature exhaust gas, the use of ceramic materials such as nitride and carbide-based sintered bodies, which have excellent heat resistance and high-temperature strength, is being considered. has been done. On the other hand, metal is used for the blades on the compressor side of the turbocharger, and it is necessary to connect them together by a metal shaft.

Normally, these ceramics and metals are joined by forming a long shaft integrally with the ceramic turbine rotor, providing a threaded part at the tip of the long shaft, and inserting this threaded part into the blade on the compressor side. Alternatively, a plurality of grooves are formed in the shaft-shaped protrusion formed integrally with the ceramic turbine rotor, and a metal blade is fitted onto the compressor side blade so as to fit into the grooves. A method has been proposed in which a cylindrical shaft is fitted and the two are shrink-fitted.

(Issues to be improved) In the former case, it is difficult to manufacture the long axis of the ceramic, and in the latter case, the bonding strength of the shrink-fitting method is low, especially when used in hot conditions, making it difficult to put into practical use. It was not possible to maintain the above durability.

(Means for Solving the Problems) The present invention was developed as a result of various studies in order to solve the above-mentioned problems.The invention includes a shaft-shaped protrusion on a ceramic blade, and a grooved metal sleeve attached to the shaft-shaped protrusion. This is a ceramic turbine rotor in which two metal shafts are fitted together, and only their mating end faces are brazed and joined.

(Function) As mentioned above, only the mating end faces are brazed and joined, and since the blades of the ceramic turbine rotor are not joined to the metal sleeve surrounding them, thermal distortion does not occur and ceramic cracking is difficult to occur, and the joining The part is located deep inside the metal sleeve and is not susceptible to oxidation even in high-temperature atmospheres, allowing good bonding strength to be maintained.

(Example) Examples of the present invention will be described below.

Reference numeral 1 denotes a ceramic turbine rotor, and 2 a short shaft-shaped protruding portion tapered 3 from a large diameter portion so as to have a diameter substantially equal to the inner diameter of the grooved metal sleeve. 4 is a metal shaft, one end of which is a grooved metal sleeve 5. 6 is an oil seal ring groove;
Reference numeral 7 indicates a joint portion, which is joined using a brazing material or the like. 3' is a tapered part at the root of the wing. The reason why 3 and 3' are rounded is to prevent stress from concentrating on the tip of the edge and causing cracks or breakage in the ceramic if the edge shape is used. 8 and 8' are center holes provided at the ends of ceramic and metal, respectively. This joint may be simply brazed, but
More preferably, as disclosed in Japanese Patent Application No. 59-80658, a thin plate made of sintered ceramic material is brazed either alone or with a buffer plate having a composite structure with a metal plate interposed therebetween, so as to be able to withstand high-temperature vibrations. However, the joint strength is strong and can prevent cracking near the joint due to residual stress after joining.

Heat-resistant ceramics such as silicon nitride and silicon carbide are used as ceramics for the turbine rotor used in implementing the present invention, and the metal shaft is made of carbon steel (JIS-S50C, etc.) and alloy layer (JIS-S50C, etc.).
SCM435), stainless steel (JIS-SUS630), maraging steel, heat-resistant steel such as Inconel, Kovar,
A heat-resistant metal such as titanium is used.

Furthermore, in the present invention, since the metal shaft and the grooved metal sleeve are integrated, the cost is lower than when the two are joined together, and there is no weakness caused by joining at high temperatures.

Next, as the brazing material, Ag--Cu eutectic brazing, titanium-silver-copper, brazing, etc. are used, but brazing materials mixed with or intervening with low expansion metals, low Young's modulus metals, etc. are preferable because of their excellent bonding strength.

(Effects of the invention) According to the invention, the shaft-shaped protrusion from the blade of the ceramic turbine rotor is fitted into the grooved metal sleeve of the metal shaft, and the mating end faces are brazed, so the effect of high temperature Since it is resistant to damage and oxidation, it can form a strong bond.

In addition, since the end of the grooved metal sleeve is located away from the blades of the ceramic turbine rotor, the ceramic does not crack due to high temperatures, and since the joint part is the end face inside the sleeve, it is less likely to be oxidized by the high temperature atmosphere and has good joint strength. can be maintained.

[Brief explanation of the drawing]

The figure is a longitudinal sectional view showing an example of the present invention. 1: Ceramic turbine rotor, 2: Shaft-like protrusion, 3: Taper, 4: Metal shaft, 5: Grooved metal sleeve, 6: Oil sealing groove, 7: Joint part.

Claims (1)

[Scope of utility model registration request] It consists of a short shaft-like protrusion that protrudes from the blades of a ceramic turbine rotor and has a tapered diameter-reduced portion, and a metal shaft that is fitted with a grooved metal sleeve that fits into this shaft-like protrusion. A ceramic turbine rotor characterized in that only internal butting end faces are brazed and joined.