JPH0524947A - Joined structural body of ceramics member and metallic member - Google Patents

Abstract

PURPOSE:To improve the joining strength between a ceramics member and a metallic member by combining the projecting part of the ceramics member and the recessed part of the metallic member in which an air vent part communicated to the outside is formed and executing shrinkage fit joining. CONSTITUTION:For joining a rotor 1 made of ceramics such as Si3N4, obtd. by integrally forming a shaft part 3 and a blade part 4 and a rotary shaft 2 made of metal such as stainless steel, the projecting part 5 of the rotor 1 is inserted into the recessed part 6 of the rotary shaft 2, and air in the recessed part 6 is flowed out through a groove 7 formed on the inner circumferential part of the recessed part 6. As the projected part 5 is inserted into the recessed part 6, the air in the recessed part 6 resisting to the insert ion is gradually forced out, and the end face of the projecting art 5 is closely contacted with the bottom face of the recessed part 6. In the above-mentioned manner, the projecting part 5 and the recessed part 6 are securely fitted with, and this joined part is subjected to shrinkage fitting to obtain a firmly joined structural body of the ceramics member and metallic member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joined structure in which a ceramic member and a metal member are joined by shrink fitting.

[0002]

2. Description of the Related Art Ceramics, which have recently been adopted as a material in a wide variety of fields, are superior in heat resistance to metals and have mechanical strength equal to that of metals. For example, the bending strength of silicon nitride is 100 Kg f / mm ² at room temperature. , 130
80kg f / mm ² at 0 ℃ Indicates the value of.

Ceramics having such excellent heat resistance are being adopted as various mechanical parts under severe operating conditions in place of parts made of metal, and one example thereof is a material for a rotor portion of a turbocharger of an internal combustion engine. Has been adopted by. A turbocharger is a device that uses exhaust energy of an internal combustion engine to rotate an exhaust turbine and uses its power to drive a compressor to precompress intake air or an air-fuel mixture. Since the rotor portion used in this turbocharger is a component that is exposed to high temperature air and rotates at high speed, it is effective to form it with ceramics having excellent heat resistance.

By the way, the rotor portion of the turbocharger has a structure in which the rotor is supported by a rotary shaft, and the rotary shaft for fixing the rotor is required to have a high processing accuracy in order to be incorporated in the turbocharger. For this reason, it is difficult to integrally form both this rotor and the rotating shaft with high processing accuracy with ceramics. Therefore, in order to solve this problem, in the rotor part of the turbocharger, the rotor, which has a high heat load, is made of ceramics, the rotating shaft with high processing accuracy is made of metal, and the two are joined together. Has been done.

Various structures have been proposed for joining the ceramic rotor and the metal rotating shaft, but a convex portion is formed at the center of rotation of the rotor and a concave portion is formed at the end of the rotating shaft. The structure in which the convex portion of (1) is inserted into the concave portion of the rotary shaft and shrink-fitted is often adopted as a simple structure. That is, the shrink fitting is a method in which a metal member is heated to a high temperature to fit the concave portion with the convex portion of the ceramic member, and the concave portion tightens the convex portion at a temperature lower than the high temperature due to a difference in thermal expansion coefficient between the both. .

[0006]

The structure for joining the ceramic rotor and the metal rotating shaft to each other has the following problems.

Since the convex portion of the rotor and the concave portion of the rotary shaft are shrink-fitted in a combined state with a fitting allowance, the outer peripheral surface of the convex portion and the inner peripheral surface of the concave portion come into extremely close contact. Therefore, when the convex portion of the rotor is inserted into the concave portion of the rotating shaft, the air in the convex portion cannot escape to the outside of the concave portion through the gap between the outer peripheral surface of the convex portion and the inner peripheral surface of the concave portion, and is pushed onto the convex portion. It is then trapped in the recess.

Therefore, due to the presence of air in this recess,
It is difficult to insert the entire convex portion into the concave portion and shrink-fit it until the end surface of the convex portion comes into close contact with the bottom surface of the concave portion. The convex part is formed with a length necessary to obtain sufficient bonding strength, and the concave part is also formed with the same length as the convex part.The entire convex part is inserted into the concave part and shrink-fitted so that both are sufficiently strong. Can be joined.

Therefore, unless the entire convex portion can be inserted into the concave portion, the joint strength between the convex portion and the concave portion, that is, the joint strength between the rotor and the rotary shaft is insufficient, and when the rotary shaft is machined after the joint or the rotor is rotated. When the joint structure of the rotating shaft and the rotary shaft is incorporated into a turbocharger and used at high temperature, slippage may occur at the joint between the convex portion and the concave portion in the axial direction or the circumferential direction,
The convex portion sometimes came off the concave portion. Also, the air in the recess becomes resistance when inserting the protrusion into the recess,
It may not be possible to smoothly insert the convex portion into the concave portion.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a highly reliable bonded structure capable of bonding a ceramic member and a metal member with sufficient strength.

[0011]

In order to solve the above-mentioned problems, a joined structure of a ceramic member and a metal member according to the present invention has a ceramic member having a convex portion and a concave portion, and the concave portion corresponds to the ceramic member. A metal member that is shrink-fitted in combination with a convex portion, wherein the metal member is formed with an air bleeding portion that communicates a bottom surface inside the concave portion and the outside of the concave portion. Is. The air vent is a groove formed by connecting the inner bottom surface of the recess and the opening of the recess on the inner peripheral portion of the recess of the metal member.

[0012]

When the convex portion of the ceramic member is inserted into the concave portion of the metal member, the air in the concave portion is pushed out of the concave portion through the air vent portion formed in the metal member. Therefore, eliminate the air in the recess that becomes a resistance when inserting the protrusion into the recess,
The entire convex portion can be inserted into the concave portion, and the convex portion and the concave portion can be jointed with sufficient strength by shrink fitting. Further, the convex portion of the ceramic member can be easily inserted into the concave portion of the metal member.

In particular, when the groove formed by connecting the inner bottom surface of the concave portion and the opening of the concave portion to the inner peripheral portion of the concave portion of the metal member is used as an air vent, the convex portion can smoothly push out the air in the concave portion. You can

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention shown in the drawings will be described below with reference to the drawings. The embodiment shown in FIGS. 1 to 4 is applied to a structure in which a rotor provided in a turbocharger of an internal combustion engine and a rotary shaft are integrally joined. FIG. 1 shows the entire bonded structure.

In the figure, reference numeral 1 denotes a rotor, which is a ceramic member, and is made of ceramics such as silicon nitride, silicon carbide, and sialon which are excellent in heat resistance. Reference numeral 2 denotes a rotating shaft which is a metal member and is made of a metal having excellent heat resistance such as chrome-molybdenum steel and stainless steel.

The rotor 1 is formed by integrally forming a shaft portion 3 and a plurality of blade portions 4 radially arranged at an intermediate position of the shaft portion 3. A convex portion 5 is formed at one end of the shaft portion 3 so as to project along the axial direction. The protrusion 5 has a boss shape with a circular cross section, and has a diameter smaller than that of the shaft 3 and a length necessary for being combined with the recess 6 of the rotary shaft 2.

The rotary shaft 2 is a round bar. As shown in FIGS. 2 and 3, a concave portion 6 is formed along the axial direction at one end of the rotary shaft 2 facing the convex portion 5 of the rotor 1. The concave portion 6 has a round hole shape that opens at the end surface of the rotary shaft 2, and has a diameter of a size that is combined with the convex portion 5 with a tightening margin and a length that is the same size as the convex portion 5. ing.

A plurality of air vent grooves 7 are formed on the inner peripheral portion of the recess 6. Each of the air vent grooves 7 is formed along the axial direction of the recess 6 by connecting the bottom surface of the recess 6 and the opening of the recess 6, and these are formed in parallel in the circumferential direction of the recess 6 with a space therebetween. Has been done. The width, the depth dimension and the number of the air vent grooves 7 are set in consideration of the conditions under which the air inside the recesses 6 can be effectively pushed out by the projections 5.

Then, the convex portion 5 of the rotor 1 is inserted into the concave portion 6 of the rotary shaft 2 to be assembled, and further shrink-fitted and joined. That is, as shown in FIG. 4, the rotary shaft 2 is heated to a high temperature to insert the convex portion 5 of the rotor 1 into the concave portion 6, and the difference in the coefficient of thermal expansion between the rotor 1 and the rotary shaft 2 is caused at a temperature lower than this high temperature. The concave portion 5 clamps and fixes the convex portion 6. In this embodiment, the joint structure of the rotor 1 and the rotary shaft 2 has the following effects.

In order to join the rotor 1 and the rotary shaft 2,
When the convex portion 5 of the rotor 1 is inserted into the concave portion 6 of the rotary shaft 2, the air in the concave portion 6 flows out from the opening of the concave portion 6 through the groove 7 formed in the inner peripheral portion of the concave portion 6. In this way, as the convex portion 5 is inserted into the concave portion 6, the air in the concave portion 6 is gradually pushed out of the concave portion 6. In this case, since the convex portion 5 is inserted while removing the air in the concave portion 6, the convex portion 5 can be smoothly inserted into the concave portion 6. Then, since the convex portion 5 discharges the air in the concave portion 6 which serves as a resistance against the insertion, the entire length direction of the convex portion 5 can be inserted into the concave portion 6, and the end face of the convex portion 5 is set to the bottom surface of the concave portion 6. Can be closely attached. Therefore, the convex portion 5 and the concave portion 6 can be securely fitted,
The rotor 1 and the rotary shaft 2 can be firmly joined by shrink-fitting and printing this joint.

When the groove 7 formed by connecting the inner bottom surface of the concave portion 6 and the opening of the concave portion 6 to the inner peripheral portion of the concave portion 6 of the rotary shaft 2 is used as an air vent, the convex portion 5 is inserted into the concave portion 6. Accordingly, the air in the recess 6 can be smoothly pushed out. In this embodiment, the air vent groove 7 is not limited to the shape along the axial direction of the recess 6, but may be a spiral shape. A specific example of the structure in which the rotor 1 made of ceramics and the rotary shaft 2 made of metal used for the turbocharger are joined will be described.

The rotor 1 is made of silicon nitride and has a convex portion 5
Has a diameter of 10 mm and a length of 10 mm. The rotating shaft 2 is made of stainless steel, and the recess 6 has a diameter of 9.98 mm and a length of 10 mm. The interference between the convex portion 5 and the concave portion 6 is 0.
It is 2 mm. The process of shrink-fitting the convex portion 5 and the concave portion 6 is
The rotating shaft 2 is heated at a temperature of 600 ° C, and the rotor is heated at a temperature of 200 ° C.
The temperature is held at 0 ° C., and the convex portion 5 of the rotor 1 is inserted into the concave portion 6 of the rotary shaft 2 by natural fall.

In the bonded structure of the present invention, the air vent portion formed in the metal member is not limited to the groove formed in the inner peripheral portion of the recess, and various forms can be adopted. For example, in FIG.
As shown in FIG. 5, in the above-described embodiment, the recess 6 is formed in the rotary shaft 2.
A plurality of air vent holes 8 may be formed along the diametrical direction to connect the bottom surface to the outside.

The present invention is not limited to a structure in which a ceramic rotor and a metal rotating shaft used in a turbocharger are bonded, but can be applied to a bonded structure used in a wide variety of other fields of application.

[0025]

As described above, the bonded structure of the ceramic member and the metal member of the present invention has a ceramic member having a convex portion and a concave portion, and the concave portion is shrink-fitted with the convex portion of the ceramic member. The metal member is provided with an air vent for communicating the bottom surface inside the recess with the outside, so that when the projection is inserted into the recess, the air in the recess is removed and the projection is removed. The whole can be smoothly inserted into the concave portion, the convex portion and the concave portion can be firmly joined together, and as a result, the ceramic member and the metal member can be joined with sufficient strength to improve reliability.

Further, when a groove connecting the inner bottom surface of the concave portion and the opening of the concave portion is formed in the inner peripheral portion of the concave portion of the metal member as an air vent, the air inside the concave portion is inserted as the convex portion is inserted into the concave portion. Can be pushed out smoothly.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing a joining structure according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a joint portion between a rotor and a rotary shaft in a joint structure.

FIG. 3 is an enlarged view showing an end face of a rotating shaft in the bonded structure.

FIG. 4 is a cross-sectional view showing a process of inserting a protrusion of a rotor into a recess of a rotary shaft in a bonded structure.

FIG. 5 is a cross-sectional view showing another example of the joint portion in the joint structure.

[Explanation of symbols]

1 ... Rotor, 2 ... Rotating shaft, 5 ... Convex part, 6 ... Recessed part, 7 ...
groove.

Claims (2)

[Claims] 1. A ceramic member having a convex portion, and a metal member having a concave portion, the concave portion being combined with the convex portion of the ceramic member by shrink-fitting and joining, the metallic member having the concave portion. A joined structure of a ceramic member and a metal member, characterized in that an air venting portion is formed which communicates the inner bottom surface with the outside of the recess. 2. The ceramic member and the metal member according to claim 1, wherein the air vent is a groove formed by connecting a bottom surface inside the recess and an opening of the recess in an inner peripheral portion of the recess of the metal member. Junction structure.