JPS6325281Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a turbine rotor in an exhaust turbocharger for an automobile engine, and more particularly to a coupling structure between a turbine rotor and a rotor shaft.

By using ceramics for turbine rotors that are exposed to high-temperature exhaust gas, it is possible to improve heat resistance, durability, weight reduction, and acceleration response. Molding a turbine rotor with blades and a rotor shaft integrally tends to cause distortion due to their shape, and it is extremely difficult to remove this through machining. Therefore, it is necessary to mold the turbine rotor and rotor shaft separately. Molded with ceramics,
These can be joined by brazing etc.
For example, Japanese Unexamined Patent Publication No. 134701/1983
This is proposed in Publication No. 89801, etc. However, the use of ceramics for the rotor shaft cannot be said to be sufficient in terms of strength such as toughness against torque fluctuations. Furthermore, since the melting point of the brazing filler metal is low, there are also problems in the heat resistance and strength of the joint.

Therefore, it is preferable to form the turbine rotor from ceramics and the rotor shaft from a metal material such as steel and connect them together. However, metal materials have a larger coefficient of thermal expansion than ceramics, so Thermal stress is generated in the fitting portion of the rotor shaft, and there is a risk that cracks may occur in the turbine rotor.

An object of the present invention is to provide a coupling structure between a turbine rotor and a metal shaft that can use a metal material as the rotor shaft, is easy to manufacture, and has sufficient coupling strength against torque.

For this reason, the configuration of the present invention is such that a bulb-shaped protrusion with a non-circular cross section is formed at the axis of the ceramic rotor, and a tightening ring fitted into the protrusion is attached to a screw hole formed at the end of the metal shaft. It is screwed together.

To explain the present invention based on an embodiment, as shown in FIG. It is constructed by fitting a tightening ring 3 made of metal and screwing this into a screw hole 6 provided at the end of a metal shaft 5.

As shown in FIG. 2, the protrusion 4 has a non-circular cross section and is configured in a bulbous or tapered shape that gradually expands at the distal end. Specifically, the cross-sectional shape of the protruding portion 4 is triangular or square, or further, a polygon with rounded corners.

The ring 3 has a notch 3a in which a hole having the same shape as the protrusion 4 is provided. Also, tightening ring 3
A thread groove is provided on the outer circumferential surface of. The turbine rotor 2 is formed by integrally molding the blades, the shaft portion 2a, and the protruding portion 4 using ceramics and sintering the blades by a known method.

The tightening ring 3 is pushed out and fitted onto the protrusion 4 formed in this way, and the tightening ring 3 is screwed into the screw hole 6 of the metal shaft 5 while rotating the turbine rotor 2. 5 comes into contact with the end surface 8 of the turbine rotor 2, and when the turbine rotor 2 is further rotated, the tightening ring 3
is tightened into the deep part of the screw hole 6, and at this time, the tightening ring 3 is pushed out and moved to the enlarged part of the protrusion 3, and this expansion is tightly tightened at the threaded part with the screw hole 6, A solid connection between the turbine rotor 2 and the metal shaft 5 is obtained.

When the turbine rotor 2 is used at high temperatures,
Since the coefficient of thermal expansion of metal is larger than that of ceramics, the tightening ring 3 tends to expand, but if the direction of rotation of the turbine rotor 2 used matches the direction in which the tightening ring 3 is screwed in, loosening can be eliminated.

As shown in Fig. 3, the material of the tightening ring 3 is an alloy such as Fe-Ni-Co alloy whose coefficient of thermal expansion is almost the same as that of ceramics, and the connecting member 7 having the screw hole 6 is also made of the same metal. If used, it is possible to eliminate loosening of the protrusion 4 and the tightening ring 3 due to thermal expansion. In this case, the connecting member 7 is frictionally welded to the end of the metal shaft 5 to couple it.

As mentioned above, this invention forms a bulbous protrusion integrally at the axis of a turbine rotor made of ceramics, a tightening ring is fitted onto this, and this tightening ring is attached to a screw at the end of a metal shaft. Since it is screwed into a hole, the assembly work is simpler than conventional brazing, and there is no looseness, providing highly reliable bonding strength at high temperatures.

Further, since the tightening ring and the metal shaft are metal-bonded, there is no problem with the bond strength, and the excellent effects of being simple to manufacture and providing at low cost can be obtained.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a coupling structure between a ceramic turbine rotor and a metal shaft according to the present invention;
2 is a front sectional view taken along the line - in FIG. 1, and FIG. 3 is a side sectional view of a coupling structure between a ceramic turbine rotor and a metal shaft according to a modified embodiment of the present invention. 2: Turbine rotor, 3: Tightening ring, 4: Projection, 5: Metal shaft, 6: Screw hole, 7: Connection member.

Claims (1)

[Claims for Utility Model Registration] (1) A bulb-shaped protrusion with a non-circular cross section is formed at the axis of a ceramic rotor, and a tightening ring fitted to the protrusion is formed at the end of a metal shaft. A joint structure between a ceramic turbine rotor and a metal shaft, which is characterized by being screwed into a screw hole. (2) The ceramic turbine according to claim (1), in which the tightening ring and the threaded hole portion of the metal shaft are made of a metal having a thermal expansion coefficient equivalent to that of ceramics, such as Fe-Ni-Co alloy. A joint structure between the rotor and metal shaft.