JPH0452451Y2 - - Google Patents

Description

[Detailed explanation of the idea]

Industrial Application Field This invention is an internal combustion engine cylinder characterized by overlaying an alloy with excellent corrosion resistance and wear resistance on the sliding surface of the internal combustion engine cylinder using a high-density energy source. It is related to. BACKGROUND OF THE INVENTION Generally, diesel engines and gasoline/methanol blend engines are subjected to harsher operating conditions than gasoline engines. For this reason, diesel engines usually include a liner that has better wear and corrosion resistance than gasoline engines. In the case of diesel engines, in recent years, as an exhaust gas purification measure, a portion of the exhaust gas is taken out of the exhaust system and returned to the intake system after controlling the temperature, timing, flow rate, etc., with the aim of reducing NOx in the exhaust gas. It has become common to install exhaust gas recirculation devices to circulate the exhaust gas, and the wear of the sliding surfaces is significantly accelerated by the carbon sulph contained in the exhaust gas that is recirculated to the intake system by the exhaust gas recirculation device. At the same time, the SOx and _H2 contained in the exhaust gas
The reaction with O produces highly corrosive sulfuric acid, and the production of the sulfuric acid makes the conditions for the sliding surface even harsher, further accelerating the wear of the sliding surface. On the other hand, in the case of gasoline/methanol mixed engines, highly corrosive acids are similarly generated, causing wear due to corrosion of cylinder sliding surfaces. As mentioned above, the wear that occurs on the cylinder sliding surface is
This is especially noticeable near the top dead center of the top ring where the piston sliding speed is slow and the oil lubricity decreases, and the area near the top dead center of the top ring becomes a stepped wear state. Conventionally, attempts have been made to deal with the above-mentioned problems by subjecting the sliding surface of the cylinder to surface hardening treatment or inserting a liner material with high wear resistance. Also, in 1987
As shown in Japanese Patent No. 84343, a method has been implemented in which the cylinder bore surface is hardened. Means to Solve the Problems However, the above conventional methods have the following problems. First, measures such as surface hardening treatment and insertion of liner material cannot actively suppress the causes of corrosive wear, and wear on the sliding surface actually occurs. In addition, when the bore surface is hardened, a martensite layer is formed on the bore surface, but as mentioned above, corrosive substances are contained in the exhaust gas that is returned to the intake system by the exhaust gas recirculation device. When this occurs, the martensite layer is corroded by the corrosive substance, so the presence of the martensite layer tends to accelerate corrosive wear. This invention was made in view of the above-mentioned conventional circumstances, and aims to reduce oil consumption and blow-by gas generation in internal combustion engines by effectively reducing wear on the sliding surfaces of internal combustion engine cylinders. The purpose is to Means to Solve the Problems In other words, the internal combustion engine cylinder of this invention has a Co-based alloy or a Ni-based alloy applied to the cylinder sliding surface from near the top dead center of the top ring to the bottom dead center of the second ring. Using a high-density energy source, a spiral band shape that is wide near the top dead center of the top ring and the bottom dead center of the second ring, and gradually narrows as it moves away from the top dead center and bottom dead center. It is characterized by overlay welding. Therefore, according to the internal combustion engine cylinder of this invention, since a wear-resistant alloy is welded overlay on the sliding surface of the internal combustion engine cylinder, the wear-resistant alloy has extremely high corrosion resistance and wear resistance. Improved. The cylinder sliding surface on which the wear-resistant alloy is overlay-welded is particularly the area from the vicinity of the top dead center of the top ring to the bottom dead center of the second ring. This is because corrosion and wear are particularly noticeable in that area. Examples of wear-resistant alloys include Ni-based alloys and Co-based alloys, and the composition thereof can be determined as necessary. The reason why the overlay weld is formed in a spiral shape centered on the sliding direction of the piston is because the top dead center of the top dead center of a conventional internal combustion engine when methanol is used as fuel was investigated. This is in consideration of the fact that wear occurs not only near the bottom dead center but also over the entire area of the bore sliding surface. In other words, in order to prevent wear over the entire area of the sliding surface of the bore, it is necessary to cover the entire area of the sliding surface with a corrosion-resistant and wear-resistant alloy. If we decide to overlay the alloy, it will have poor workability and cause cost problems.
A spiral build-up welded portion centered on the sliding direction of the piston is formed over the entire sliding surface area. Also, if the overlay welding area is too wide, there is a problem that distortion will occur due to heating, but on the other hand, if a wear-resistant alloy is locally overlaid welded, there is a risk that thermal conductivity will differ locally and thermal stress will increase. Therefore, in the present invention, the width of the spiral band-shaped overlay welding portion is made narrower as it moves away from the top dead center of the top ring and the bottom dead center of the second ring. In addition, as a high-density energy source, well-known means,
For example, a laser, an electron beam, an arc, etc. can be used. The energy density of the beam or the like irradiated by these high-density energy sources can be appropriately set depending on the type of wear-resistant alloy used. By using such a high-density energy source, melting of the base material (internal combustion engine cylinder block) can be minimized and a high-quality overlay weld layer can be formed. Examples Examples of this invention are described below. Example 1 FIG. 1 shows a cylinder block obtained by implementing this invention. As shown in the figure, a band-shaped overlay weld 2 parallel to the direction of movement of the piston was formed on the cylinder sliding surface of the cylinder block 1. As shown in the figure, the overlay weld 2 extends from near the top dead center of the top ring to the bottom dead center of the second ring, and extends over the entire circumference of the cylinder sliding surface so as to cover the bottom dead center of the second ring. It was formed into a spiral shape. At that time, the width of the spiral welded part 2 is made so that it is widest at the top dead center of the top ring and the bottom dead center of the second ring, and as shown in the figure, Welding was performed so that the width of the overlay welded portion 2 decreased as the distance from the bottom dead center of the ring increased. As a result of welding with the above considerations in mind, the first
The dimensions of each part A to E in the figure are as shown below.
A=15mm, B=7mm, C=40mm, D=35mm, E=
7mm. In addition, the material for the overlay weld is a first-class material that has better corrosion and wear resistance than the cylinder block material metal.
A Ni-based alloy with the composition shown in the table was used.

[Table] Furthermore, overlay welding was performed under the conditions shown in Tables 2 and 3.

【table】

[Table] Example 2 The present invention was carried out in the same manner as in Example 1 except that a stainless steel member having the composition shown in Table 4 was used as the material for the overlay weld, and the welding conditions were as shown in Table 5. carried out.

【table】

[Table] Example 3 The present invention was carried out in the same manner as in Example 2 except that a Co-based member having the composition shown in Table 6 was used as the material for the overlay weld.

[Table] Durability tests were conducted on the cylinder blocks obtained in Examples 1 to 3 above. Durability Test The durability test was conducted under the conditions shown in Table 7.

[Table] Figure 2 shows the results of the above durability test. As shown in Figure 2, while the conventional product has a wear amount of 188μ, the Ni overlay product of Example 1 has a significantly reduced stepped wear amount of about 1/10, and is corrosion resistant. It can be seen that the characteristics are significantly improved. In addition, the stepped wear amount of the stainless steel overlay product of Example 2 is about 1/8 of that of the conventional product, and furthermore, the stepped wear amount of the Co overlaid product of Example 3 is about 1/9 of that of the conventional product. It can be seen that the corrosion and wear resistance properties are also significantly improved in the case of . Effects of the invention As described above, according to the internal combustion engine cylinder of this invention, a wear-resistant alloy is overlay-welded on the sliding surface of the internal combustion engine cylinder using a high-density energy source.
It has the effect of being significantly superior in wear resistance compared to the conventional case where the material is made of cast iron. In addition, in this design, the wear-resistant alloy is welded in a spiral band shape, and the width becomes narrower as it moves away from the top dead center of the top ring and the bottom dead center of the second ring, thereby suppressing thermal distortion during welding. Not only is this possible, but it is also possible to prevent local rapid changes in the thermal conductivity of the cylinder sliding surface and to alleviate thermal stress during operation of the internal combustion engine. Thereby, the amount of oil consumed and the amount of blow-by gas generated in the internal combustion engine can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a partially exploded view of an internal combustion engine cylinder block in which this invention is implemented, and FIG. 2 is a diagram showing the wear characteristics of the internal combustion engine cylinder obtained by an embodiment of this invention. 1... Cylinder block, 2... Overlay welding part.

Claims (1)

[Scope of utility model registration request] On the cylinder sliding surface, from the top dead center of the top ring to the bottom dead center of the second ring, Co
Ni-based alloy or Ni-based alloy uses a high-density energy source to widen the width near the top dead center of the top ring and the bottom dead center of the second ring, and as it moves away from the top dead center and bottom dead center of the second ring. An internal combustion engine cylinder characterized by overlay welding in the form of a spiral band whose width gradually becomes narrower.