JPH05321757A - Engine parts and its manufacture - Google Patents

Abstract

PURPOSE:To provide an engine part which is excellent in the heat insulation, the heat resistance and the durability by providing an annular notch part to the end part on the ceramics member side on the outer circumference of metallic members, and fixing it to the engine part body by shrinkage fit. CONSTITUTION:A metallic member 32. whose outer circumferential diameter is smaller than that of a ceramics member 30, and the ceramics member 30 are integratedly joined to each other through a metallization layer 38 adhered to the ceramics member 30. The ceramics member 30 and the metallic engine part body are integratedly connected to each other through the metallic member 32. In particular, an annular notch part 33 is provided in the end part of the ceramics member side at the outer circumference of the metallic member 32. The metallic member 32 is fixed to the metallic engine part body at the outer circumferential diameter part by shrinkage fit or by threading. This arrangement easily provides a part which is excellent in the heat insulation, the heat resistance or the like by making advantage of the characteristics of the ceramics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine part made of ceramics and a metal having excellent heat insulation, heat resistance and durability, and a method for producing the same.

[0002]

2. Description of the Related Art Since ceramic materials are excellent in mechanical strength, heat resistance, oxidation resistance, and heat insulation, the parts that come into contact with high-temperature combustion gas such as engine pistons, cylinder liners, cylinder heads, etc. are made of ceramic materials. If configured, it is possible to improve combustion temperature and reduce heat loss,
Effects such as engine efficiency improvement and reduction of harmful components in exhaust gas can be expected. In addition, if a portion such as a tappet or a rocker arm pad that receives repeated impact loads is made of a ceramic material, it is effective in improving wear resistance. For this reason, engine parts that combine metal engine parts and ceramic parts have been proposed.

For example, an engine piston in which a ceramic piston cap is fixed to the top of a metal piston with a cast ring is disclosed in JP-A-58-95674 and US Pat. No. 4,245.
No. 611.

[0004]

However, in order to fix the ceramic piston cap to the metal piston body with the cast metal, it is necessary to reduce the casting stress due to the difference in thermal expansion between the ceramic piston cap and the metal piston body. .. As a means for this, there is a method (Japanese Unexamined Patent Publication No. 58-95674) for relaxing the casting stress with a metal ring mounted on a ceramic piston cap. But,
In this method, since it is necessary to form a flange portion for mounting the metal ring on the ceramic piston cap, not only the shape of the ceramic piston cap becomes complicated, but also cracks due to stress concentration in the corner portion of the flange. There are drawbacks that are likely to occur.

There is also a method (US Pat. No. 4,245,611) of relaxing the casting stress by interposing a cushion layer made of a fibrous ceramic material between the ceramic piston cap and the metallic piston body. However, this method has a drawback that the ceramic piston cap is insufficiently fixed to the metal piston body due to the presence of the cushion layer, and the piston cap becomes loose during use of the piston.

Furthermore, a method of fixing a ceramic piston cap to a cast piston with a cast ring is as follows:
Since there is a need to preheat the ceramic piston cap in order to prevent the ceramic piston cap from being broken by the thermal shock caused by the injection of the molten metal, there is a drawback that the casting operation becomes complicated.

In order to solve various drawbacks associated with such cast metal, a metal member is fixed to a ceramic piston cap, and then an outer peripheral portion of the metal member is processed,
There is a method of fixing to the metal piston body by a mechanical coupling method such as shrink fitting or screwing. However, this method also has a drawback that when the outer peripheral portion of the metal member is processed, the processing tool comes into contact with the surface of the ceramic piston cap, and the ceramic piston cap is damaged.

The object of the present invention is to easily process the ceramic member without damaging the ceramic member during manufacturing, and to freely select the combination of the ceramic member and the material forming the metal engine component body. It is an object of the present invention to provide an engine component having excellent heat insulation, heat resistance and durability, and a method for manufacturing the same.

[0009]

The features of the present invention are as follows. A first invention, a metal member having an outer peripheral diameter smaller than the outer diameter of a ceramic member, and a ceramic member are integrally joined via a metallized layer adhered to the ceramic member, and In an engine component having a structure in which the ceramic member and the metal engine component body are integrally connected via a metal component, the ceramic member on the outer peripheral portion of the metal component is annular at the end. An engine component, wherein a notch portion is provided, and the metal member is fixed to the metal engine component main body at a large diameter portion on the outer periphery by shrink fitting or screwing.

Second Invention A metal member having a diameter of the outer peripheral portion smaller than the outer diameter of the ceramic member and the ceramic member are integrally joined via a metallization layer adhered to the ceramic member,
In addition, in the method of manufacturing an engine component in which the ceramic member and the metal engine component body are integrally connected to each other through the metal component to form an engine component, the ceramic component and the ceramic member whose outer diameter is A metallized layer having a smaller diameter than the outer diameter and having an annular cutout at one end of the outer periphery is attached to the ceramic member such that the annular cutout is located in the ceramic member. After joining through the metal member, a predetermined finishing process is applied to the large diameter portion of the outer periphery of the metal member, and the metal member is fixed to the metal engine component body by shrink fitting or screwing at the finish processing unit. Manufacturing method of engine parts characterized by.

According to the present invention, a metal member having an outer peripheral diameter smaller than the outer diameter of the ceramic member is fixed to the ceramic member, and the ceramic member and the metal engine part body are joined through this metal member. To do. Since the outer diameter of the metal member changes depending on the attachment to the ceramic member, the outer peripheral portion of the metal member is processed after the attachment to the ceramic member. An annular notch is formed in advance at the outer edge of the ceramic member on the outer peripheral portion of the metal member by any one of outer rounding, rounding and chamfering. As a result, a gap corresponding to the distance from the starting point of the notch to the surface of the ceramic member is formed on the outer peripheral portion of the metal member, so that the tool is made of ceramic during finish machining of the outer peripheral portion such as thread cutting. Since it does not come into contact with the surface of the member, not only the outer peripheral portion of the metal member is easily processed, but also the ceramic member is not damaged. The depth and width of the annular notch provided in the metal member are determined according to the machining allowance for finishing the outer peripheral portion, the shape and size of the tool to be used, and the machining method.

In the present invention, the ceramic member is made of a ceramic material selected from the group consisting of zirconia, alumina, silicon nitride, silicon carbide and sialon. As the metal member, a metal whose coefficient of thermal expansion is equal to or lower than the coefficient of thermal expansion of the metal constituting the body of the metal engine component is used.

The ceramic member and the metal member are fixed to each other by bonding the ceramic member to the metal member through a metallized layer adhered to the surface to be bonded.

The term "metallized layer" as used herein means that in order to metallize the surface of the ceramic member, a paste composition containing metal powder as a main component is applied to the surface of the ceramic member and then dried, and then a reducing atmosphere, It is a metal layer deposited on the surface of a ceramic member by heating in a non-oxidizing atmosphere or a hydrogen atmosphere in which the partial pressure of water vapor is adjusted.

In the present invention, the composition of the metallized layer deposited on the ceramic member is selected according to the ceramic material forming the ceramic member. For example, when the ceramic member is a partially stabilized zirconia ceramic containing Y ₂ O ₃ , Mo: 70 to 90% by weight, Mn
O: 0.5 to 15 _{wt%, Y 2 O 3: 0.1} ~10 wt%, Al
_A metallized layer composed of ₂ O ₃ : 0.1 to 15% by weight and SiO ₂ : 0.1 to 15% by weight is particularly preferable because of its high bonding strength.

The metallized layer and the metal member may be joined by either brazing or diffusion joining, but they are used depending on the mechanical properties such as joining strength, fatigue strength and high temperature strength required for the joint. Determine the brazing material and insert metal for diffusion bonding. In addition, in order to reduce the difference in thermal expansion between the ceramic member and the metal member between the metallized layer applied to the ceramic member and the metal member, a metal plate whose coefficient of thermal expansion is equal to or less than that of the metal member is buffered. You may interpose as a metal body and join.

In the present invention, the reason why the ceramic member and the metal member are joined via the buffer metal body is to reduce the difference in thermal expansion between the ceramic member and the metal member. The effect of joining via a buffer metal body is to reduce the thermal stress generated during cooling from the joining temperature and also the thermal stress generated by the thermal cycle acting during use. This improves the reliability of the ceramic member in use. The metal member fixed to the ceramic member and the metal engine component body are coupled by shrink fitting or screwing.

Next, embodiments will be described with reference to the drawings.
1 and 2 are longitudinal sectional views of an engine component of the present invention in which the ceramic member is a piston cap and the metal engine component body is a piston body.

FIG. 1 shows a disk-shaped piston cap 30 made of zirconia ceramics, a metallic member 32 made of spheroidal graphite cast iron having a smaller diameter than the piston cap, and a disk-shaped titanium buffer metal body 37 having a diameter smaller than the diameter of the metallic member. The piston cap 30 is composed of a spheroidal graphite cast iron piston main body 34, and via a metallized layer 38 adhered to one surface of the piston cap and a titanium buffer metal body 37 brazed to the metallized layer.
And the metal member 32 are joined by brazing. The piston cap 30 and the piston body 34 are joined by shrink fitting of the outer peripheral portion of the metallic member 32 and the inner peripheral surface 35 of the recess at the top of the piston body 34. This piston is made, for example, as follows.
First, a piston cap having a predetermined shape is fired from partially stabilized zirconia ceramics containing Y ₂ O ₃ and then processed into a predetermined size.

Next, a metallized layer 38 having a predetermined composition is applied to one surface of the piston cap, and the surface of the metallized layer 38 is plated with Ni. In addition, one side of the metal member 32 is Ni
Apply plating. A titanium disk 37 having a diameter smaller than that of the metal member 32 is sandwiched between the Ni-plated surface of the metal member 32 and the metallization adhered surface of the piston cap, and the surfaces that are in contact with each other are brazed. As the brazing material to be used, a brazing material having a necessary bonding strength at the operating temperature of the piston, for example, a silver brazing material, a Cu—Mn alloy brazing material, or a Ni brazing material is used. Then, the outer peripheral surface of the metal member 32 is processed into a predetermined size.

In the embodiment shown in FIG. 1, the outer peripheral surface 37A of the titanium disk 37 has a smaller diameter than the inner peripheral surface 35 of the tip of the piston body 34, and is provided between the titanium disk 37 and the inner peripheral surface 35 of the tip of the piston body 34. An annular gap 33 is formed.

Next, a recess inner peripheral surface 35 having a predetermined size for fitting the metal member 32 on the top is processed, the piston body is heated to a predetermined temperature, and the recess inner peripheral surface 35 is covered with the metal member. Shrink 32 to connect piston cap 30 and piston body 34. It is desirable that the shrink fit temperature be equal to or lower than the melting point of the brazing material used for brazing the piston cap 30 and the metal member 32 and that the metal structure of the metal forming the piston body 34 does not change. The shrink fitting allowance should be large enough to obtain the required tightening force at the operating temperature of the piston.

FIG. 2 is a metal member made of spheroidal graphite cast iron having a piston cap 20 made of zirconia ceramics and an annular notch 23 having a small diameter at the outer peripheral portion of the end of the piston cap.
22, an aluminum alloy piston body 24, and a piston cap 20 via a metallization layer (not shown) attached to the top surface 21 of the convex portion provided on the piston cap.
And the metal member 22 are joined.

The piston cap 20 and the piston body 24 are
The screw is provided on the outer peripheral portion of the metal member 22 and the screw is provided on the inner peripheral surface 25 of the recess of the top of the piston main body so as to be screwed together.

If necessary, a ceramic heat insulating material 26 may be provided on the bottom surface of the metal member. This piston is made, for example, as follows. First, a piston cap having a predetermined shape is fired from partially stabilized zirconia ceramics containing Y ₂ O ₃ and processed into a predetermined size. After the protrusion top surface 21 of the piston cap and dried by applying a paste-like compositions based on _{Mo-Mn-SiO 2 -Al 2} O 3, having a predetermined composition on the surface by heating in a humidified atmosphere of hydrogen Deposit a metallization layer. Ni plating is applied to the surface of the metallized layer.

On the other hand, a disk of spheroidal graphite cast iron is prepared, and a concave portion 28 for arranging the convex portion of the piston cap is formed on one surface of the circular plate, and the outer peripheral portion of the open end of the concave portion 28 is formed. An annular notch 23 having a smaller diameter than the outer peripheral portion is provided, and the inner peripheral surface is chamfered to form a metal member 22. N on the bottom of the recess 28
After i-plating, the convex portion 21 of the piston cap is disposed in the concave portion, and the opposed surfaces of the convex portion 21 of the piston cap and the concave portion 28 of the metal member are joined with silver solder. After that, the large diameter part of the metal member 22 and the piston body
24 A screw of a predetermined size is machined on each of the inner peripheral surfaces 25 of the recesses for disposing the metal member 22 provided on the top. This screw connects the piston cap and the piston body.

[0027]

As is clear from the above description, the engine component of the present invention has the metallized layer 38 adhered to the inner surface of the ceramic member 30 and the titanium buffer metal body 37 brazed to the metallized layer. Are connected to the metal member 32, the ceramic member 30 and the metal member
In the case of joining with 32, it can be joined without heat treatment. It is not necessary to consider the difference in the coefficient of thermal expansion between the ceramic member 30 and the metal member 32. The metal member 32 and the piston body 34 are joined to each other by the inner surface 35 of the concave portion of the piston body 34 and the metal member.
Although it is joined by shrink fitting with the outer peripheral surface of 32, an annular notch 33 is provided between the titanium buffer metal body 37 joined to the ceramic member 30 and the inner surface 35 of the tip recess of the piston body 34. During the shrink fitting, no pressure is applied to the buffer metal body 37, and the ceramic member 30 is not damaged.

Further, since the metal member fixed to the ceramic member and the metal engine part body can be joined together without the need for heat treatment, the property of the heat-treated metal engine part body 34 can be changed. Instead, it can be joined to the ceramic member 30. Furthermore, even with respect to the engine component body 34 made of a low melting point metal such as an aluminum alloy, the ceramic member 30 can be coupled to the engine component body 34 without using a complicated manufacturing method such as casting. .. As described above, the engine component of the present invention can be easily made into an engine component having excellent heat insulating property, heat resistance, or wear resistance by utilizing the features of ceramics such as heat insulating property, heat resistance, corrosion resistance, and wear resistance. it can.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a vertical sectional view of a piston which is an embodiment of an engine component of the present invention.

FIG. 2 is an explanatory view showing a vertical sectional view of a piston which is an embodiment of the engine component of the present invention. 20 Ceramic Piston Cap 21 Top Surface of Convex Part on Piston Cap 22 Metal Member 23 Annular Notch 24 Metal Piston Body 25 Recess Inner Surface of Piston Body 26 Heat Insulating Material 28 Recess on Metal Member 30 Ceramic Piston Cap 32 Metal member 33 Annular notch 34 Metal piston main body 35 Recess inner peripheral surface on piston main body 37 Buffer metal body (titanium disk) 37A Outer peripheral surface 38 Metallized layer

Claims (4)

[Claims] 1. A metal member having an outer peripheral diameter smaller than the outer diameter of a ceramic member and a ceramic member are integrally joined via a metallized layer adhered to the ceramic member, Moreover, in an engine component having a structure in which the ceramic member and the metal engine component body are integrally connected via the metal member, the ceramic member on the outer peripheral portion of the metal member is formed at the end portion. An engine component, wherein an annular notch is provided, and the metal member is fixed to a metal engine component body by shrink fitting or screwing at a large diameter portion of the outer periphery. 2. A buffer metal body is interposed between a metallized layer applied to a ceramic member and a metal member, and the buffer metal body forms a part or all of a cutout portion of an outer peripheral surface of the metal member. The engine component according to claim 1, wherein 3. A metal member having an outer peripheral diameter smaller than the outer diameter of the ceramic member and the ceramic member are integrally bonded via a metallized layer adhered to the ceramic member, and the metal is In the method of manufacturing an engine component in which the ceramic member and the metal engine component main body are integrally combined to form an engine component through the ceramic component, the ceramic member and the outer peripheral diameter are smaller than the outer diameter of the ceramic member. A metal member having a small diameter and having an annular cutout portion at one end of the outer circumference is formed through a metallized layer adhered to the ceramic member such that the annular cutout portion is located on the crocodile. After joining, a predetermined finishing process is applied to the large diameter part of the outer periphery of the metal member,
A method of manufacturing an engine component, wherein the metal member is fixed to the main body of the metal engine component by shrink fitting or screwing at the finishing portion. 4. A metallurgical layer adhered to a ceramic member and a metal member are joined together with a buffer metal body interposed therebetween, and the buffer metal body is a part of a cutout portion of an outer peripheral surface of the metal member or The method of manufacturing an engine component according to claim 3, wherein the engine component is entirely formed.