Cylinder liner, and joint between the cylinder liner and the cylinder block

Abstract

The objective is to provide a cylinder liner that can achieve both engine vibration suppression and bonding strength. [Solution] The problem is solved by a cylinder liner having a plurality of protrusions on its outer surface, wherein the outer surface of the cylinder liner has a thermal spray layer only on the tops of the plurality of protrusions.

Description

Technical Field

[0001] The present invention relates to a cylinder liner with enhanced bonding strength to a cylinder block. It also relates to a bonded body of a cylinder liner and a cylinder block.

Background Art

[0002] In order to improve the bonding strength between a cylinder liner and a cylinder block surrounding it, there is a technique of improving the adhesion by forming protrusions on the outer peripheral portion of the cylinder liner (see Patent Document 1). On the other hand, as a technique for suppressing engine vibration or noise caused by this vibration, for example, there is a technique of providing an elastic repulsive portion between the cylinder block and the cylinder head of the engine (see Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to suppress engine vibration, the inventors of the present invention attempted to form a film made of an elastic body on the surface of a cylinder liner having protrusions on its outer peripheral portion and bond it to a cylinder block. However, when providing a film on the outer peripheral portion of the cylinder liner, if an elastic body is filled between the protrusions on the outer peripheral portion of the cylinder liner, vibration can be significantly suppressed, but the bonding strength obtained by casting the elastic body between the protrusions together with the outer peripheral portion of the cylinder liner is lost, and the bonding strength that should originally be obtained by providing protrusions on the outer peripheral surface of the cylinder liner cannot be obtained. The present invention provides a cylinder liner that can solve such problems.

Means for Solving the Problems

[0005] The inventors of the present invention have investigated and found that the above problems can be solved by having a thermal spray layer on the top of the protrusions in a cylinder liner having protrusions on its outer surface.

[0006] One embodiment of the present invention is a cylinder liner having a plurality of protrusions on its outer circumferential surface, The cylinder liner is such that the outer surface of the cylinder liner has a thermal spray layer only on the tops of the multiple protrusions. Another embodiment of the present invention is a cylinder liner having a plurality of protrusions on its outer surface, The plurality of protrusions have a thermal sprayed layer at their tops, and elastic material is filled between the plurality of protrusions, forming a cylinder liner. Preferably, the thermal sprayed layer is an aluminum alloy thermal sprayed layer.

[0007] Another embodiment of the present invention is a joint comprising a cylinder liner having a plurality of protrusions on its outer circumferential surface and a cylinder block joined to the cylinder liner, wherein the outer circumferential surface of the cylinder liner has a thermal spray layer only on the tops of the plurality of protrusions. Another embodiment of the present invention is a joint comprising a cylinder liner having a plurality of protrusions on its outer surface and a cylinder block joined to the cylinder liner, The aforementioned plurality of protrusions have a thermal sprayed layer at their tops, and the space between the plurality of protrusions is filled with an elastic member, forming a jointed body. [Effects of the Invention]

[0008] The present invention provides a cylinder liner that can achieve both engine vibration suppression and maintenance of the bonding force between the cylinder liner and the cylinder block. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing an enlarged view of the protruding portion on the outer surface of the cylinder liner. [Figure 2] This is a schematic cross-sectional view showing an enlarged view of the joint portion of the assembly where the cylinder liner and cylinder block are joined. [Figure 3] This is a schematic cross-sectional view showing an enlarged view of the joint portion of the assembly where the cylinder liner and cylinder block are joined. [Figure 4] This is a magnified microscope image of the joint portion of a joint (Example 1) in which a cylinder liner and a cylinder block are joined (photograph used as a substitute for a drawing). [Figure 5] This is a magnified microscope image of the joint portion of the joint between the cylinder liner and the cylinder block (Example 2) (photograph used as a substitute for drawing). [Modes for carrying out the invention]

[0010] The present invention will be described in detail below, but its scope is not limited by the following description. One embodiment of the present invention is a cylinder liner having a plurality of protrusions on its outer surface. This will be described in detail with reference to Figure 1.

[0011] Figure 1 shows a schematic cross-sectional view of the cylinder liner surface. The cylinder liner has multiple protrusions on its outer circumferential surface, extending from the bottom to the top in the figure. From the viewpoint of the bonding force between the cylinder liner and the cylinder block, it is preferable that these protrusions are constricted.

[0012] The number and height of the protrusions are not particularly limited, but from the viewpoint of joint strength, it is preferable that the average height H of the protrusions is 0.4 mm or more and 1.0 mm or less. Note that the protrusion height h shown in the cross-sectional view (Figure 1) is the distance between the bottom of the protrusion and the outermost surface of the protrusion, but since this is not necessarily the cross-section that passes through the maximum height of the protrusion, the average height H is used. Also, the surface of the cylinder liner is 100 mm 2 The number of protrusions per unit is usually preferably between 10 and 100, and the protrusions are preferably constricted. For an understanding of constricted protrusions, see, for example, Patent Document 1.

[0013] <Total number of protrusions and average height of protrusions> The number of protrusions and the average height of the protrusions (hereinafter also simply referred to as "the height of the protrusions") were measured with a 3D measuring instrument (Keyence VR-3000 series) at a magnification of 25 times and a measurement field of view of 12 mm × 9 mm. The measured data was subjected to curvature correction using the analysis software attached to the Keyence VR-3000 series. The correction condition was a quadratic surface correction. Next, a reference plane was set. The reference plane was automatically set by area designation. The threshold value was set to about 1 / 2 to 1 / 3 of the protrusion height, and was 0.25 mm at the time of this measurement. The height region exceeding the threshold value was regarded as a protrusion, and the number thereof was regarded as the number of protrusions. This number of protrusions was taken as the total number of protrusions existing within the field of view - the number of protrusions straddling the boundary of the field of view × 1 / 2. From the measured number of protrusions and the field of view area, the total number of protrusions per unit area was determined. The height of each protrusion was taken as the total value of the display range center + threshold value + maximum height. The display range center is a parameter set on the device side according to the properties of the cylinder liner to be measured, and represents the height from the base surface of the protrusion to the reference plane. The threshold value represents the height from the reference plane, and the maximum height represents the height from the threshold value to the tip of the protrusion. By reading the maximum height of each protrusion, the height of the protrusion could be measured, and the average height H of the protrusions was determined from the average value thereof. Since the height and base surface of the protrusions change in value depending on the observation direction due to the shape of the protrusions, they were fixed in the arbitrarily determined measurement direction during measurement, and all of the measurement field of view range was measured. This analysis was performed at four locations on one cylinder liner, and the average value thereof was determined. These four locations were two locations each at positions approximately 20 mm from both ends of the cylinder liner, and were positions shifted from each other by approximately 90° at both ends.

[0014] Figure 2 is an enlarged cross-sectional schematic view of the joint portion between the cylinder liner of the present embodiment and the cylinder block joined to the cylinder liner. The upper part in Figure 2 is the cylinder block portion region, and the lower part in Figure 2 is the cylinder liner solid portion region.

[0015] The cylinder liner of this embodiment has a sprayed layer as shown by hatching in the figure only on the top of the protrusion. By having a sprayed layer on the top of the protrusion, the bonding force between the protrusion part and the cylinder block is improved. Specifically, as shown in FIGS. 4 and 5, the sprayed layer on the top of the protrusion penetrates into the cylinder block and integrates, thereby improving the bonding force between the cylinder liner and the cylinder block.

[0016] As long as there is a sprayed layer on at least one top of the protrusion, the sprayed layer on the top of the protrusion can improve the bonding force between the cylinder liner and the cylinder block. However, from the perspective of enhancing the bonding force, it is preferable to have a sprayed layer on the tops of 50% or more of the protrusions, and it is more preferable to have a sprayed layer on the tops of all the protrusions.

[0017] Note that "only on the top of the protrusion" typically means within the region indicated by the vertical dotted line in the protrusion part on the left center in FIG. 2, which will be described in more detail using FIG. 3. When the cylinder liner is cut into two parts along the cylinder liner axial direction, two divided cross-sections appear. The axial average length of the sprayed layer on the cross-section attached to a plurality of protrusions on one of these cut surfaces may be 70% or more and 130% or less of the average value of the maximum axial length of the protrusions on the cut surface. Also, in the range of 100 mm 2 from the outer circumference in the radial direction, the area of the sprayed layer in a plurality of protrusions may be 70% or more of the area of the top of the protrusion.

[0018] Specifically, in the cross-sectional view shown in Figure 3, the axial lengths of the protrusions are represented by d1, d2, and d3. On the other hand, the axial lengths of the thermal spray layer are represented by ds1, ds2, and ds3. Even when the cylinder liner is cut along the axial direction of the cylinder liner, the cut does not include the entire center of the protrusion, so the maximum diameter of the protrusion and the maximum length of the thermal spray layer cannot necessarily be measured in that cross-section. In cases such as the protrusion on the left in Figure 3, where the length ds1 of the thermal spray layer is longer than the axial length d1 of the protrusion, in cases such as the protrusion in the center of Figure 3, where the length ds2 of the thermal spray layer is shorter than the axial length d2 of the protrusion, and in cases such as the protrusion on the right in Figure 3, where the length ds3 of the thermal spray layer is almost the same as the axial length d3 of the protrusion. Therefore, the average length of the thermal spray layer attached to multiple protrusions should be between 70% and 130% of the average value of the maximum axial lengths of the protrusions in the cross-section.

[0019] The type of thermal spray layer is not particularly limited and can be appropriately selected depending on the type of cylinder block. Specifically, examples include iron alloy thermal spray, aluminum alloy thermal spray, and ceramic alloy thermal spray. For example, when the cylinder block is formed by aluminum die casting, the thermal spray layer on the top of the protrusions of the cylinder liner can be an aluminum alloy thermal spray layer. Furthermore, the thickness of the thermal spray layer is not particularly limited, but is usually between 0.1 mm and 0.3 mm, and preferably between 0.15 mm and 0.25 mm.

[0020] The thermal spraying method used for forming the thermal spray layer is not particularly limited, and known methods can be applied, specifically including plasma spraying, arc spraying, flame spraying, and gas spraying. In addition, the top of the cylinder liner protrusion or the entire cylinder liner may be preheated to improve the adhesion between the top of the cylinder liner protrusion and the thermal spray layer.

[0021] Furthermore, in this embodiment, as shown in Figure 2, it is preferable that an elastic member is filled between the protrusions indicated by the dashed line. By filling the protrusions of the cylinder liner with an elastic member, the engine By absorbing noise and vibration with elastic materials, noise and vibration can be suppressed.

[0022] The effect of suppressing engine noise and vibration can be achieved even if only a small amount of elastic material is filled between the protrusions of the cylinder liner, but in order to achieve a sufficient effect, it is preferable that the elastic material is filled so that the outer surface of the cylinder liner is not exposed between the protrusions. More specifically, in a cross-sectional view of a cylinder liner including protrusions, the region from the base to the apex of adjacent protrusions (shown by dotted lines at the base and apex of the protrusions in Figure 1) is defined as the inter-protrusion region, and it is more preferable that the filling rate of the elastic material in the inter-protrusion region is high.

[0023] The elastic member is not particularly limited as long as it can suppress engine noise and vibration, and examples include resin materials and rubber materials. From the viewpoint of heat resistance, silicone rubber is preferred as the elastic member. The silicone rubber preferably has a Shore A hardness of 25 to 50. Furthermore, when applying the silicone rubber to the outer surface of the cylinder liner, it is preferable that the viscosity of the silicone rubber in its liquid state before curing is between medium viscosity of 100 Pa·s and low viscosity of 10 Pa·s or paste-like, as this facilitates the application process.

[0024] The presence of elastic material between the cylinder liner protrusions, and the degree of elastic material filling, can be confirmed by cutting the cylinder liner, or the joint between the cylinder liner and the cylinder block, along the axial direction and observing the cross-section of the cylinder liner protrusions and the spaces between them using a metallurgical microscope or the like.

[0025] The method for manufacturing the cylinder liner of this embodiment is not particularly limited, as long as it can manufacture a cylinder liner having a plurality of protrusions on its outer circumferential surface and elastic members in at least a portion of the spaces between the plurality of protrusions. A cylinder liner having protrusions can be manufactured, for example, by the method described in Patent Document 1.

[0026] The method for filling the spaces between the protrusions of the cylinder liner with resin or rubber material is not particularly limited. For example, by filling the spaces between the protrusions with an elastic material, an elastic material can be placed in the recesses between the protrusions of the cylinder liner.

[0027] Furthermore, the method for manufacturing the joint is not particularly limited and known methods can be employed. For example, the method may include the steps of preparing a mold for a cylinder block, placing the cylinder liner of this embodiment into the prepared mold for a cylinder block, and pouring molten metal into the mold for a cylinder block in which the cylinder liner is placed to form a cylinder block. [Examples]

[0028] The present invention will be described in more detail below with reference to examples, but it goes without saying that the scope of the present invention is not limited by the following examples. <Manufacturing of cylinder liners> A cast iron cylinder liner was manufactured according to the method described in Patent Document 1. The manufactured cylinder liner had an outer diameter (outer diameter including the height of the projection) of 85 mm, an inner diameter of 74 mm (wall thickness of 5.5 mm), and an axial length of 130 mm. Furthermore, the cylinder liner has multiple constricted protrusions on its outer surface, with an average height of 0.7 mm and 100 mm. 2 The number of protrusions that were hit was 37.

[0029] <Example 1> Next, silicone rubber A (viscosity 70 Pa.s) was filled into the outer surface of the cylinder liner. After filling, an Al-Si thermal spray layer was formed on the top surfaces of the multiple protrusions present. The cylinder liner was cast into a cylinder block formed by die-casting aluminum, creating a joined body. Figure 4 shows a magnified image of the joint between the cylinder liner and the cylinder block. The thickness of the thermal spray coating was measured to be approximately 0.11 mm. Furthermore, it was confirmed that silicone rubber was filled between the multiple protrusions.

[0030] <Example 2> A joint was obtained in the same manner as in Example 1, except that the filling was done with silicone rubber (B, paste form) and the thickness of the Al-Si thermal spray layer was increased. Figure 5 shows a magnified image of the joint between the cylinder liner and the cylinder block of the joint. The thickness of the thermal spray layer was measured to be approximately 0.25 mm. Furthermore, it was confirmed that silicone rubber was filled between the multiple protrusions.

[0031] <Comparative Example 1> A bonded body was obtained in the same manner as in Example 1, except that an Al-Si thermal spray layer was not formed. <Comparative Example 2> A bonded body was obtained in the same manner as in Example 2, except that an Al-Si thermal spray layer was not formed.

[0032] <Joint Strength Test> The bond strength of the joints obtained in Examples 1 and 2, and Comparative Examples 1 and 2, was measured by the following method. Using a tensile testing machine (Shimadzu Corporation, universal testing machine: AG-5000E), one of the cylinder liner and cylinder block was fixed with a clamp, and a tensile load was applied to the other in a direction approximately perpendicular to the joint surface of the two members. The tensile strength at which the two members separated was defined as the joint strength. The results are shown in Table 1. The results are the average of 15 evaluations of cylinder blocks manufactured using the same method, and are shown as relative strengths with the strength of Comparative Example 2 set to 1. Note that Comparative Example 1 separated before the tensile load was applied.

[0033] [Table 1]

Claims

1. A cylinder liner having multiple protrusions on its outer surface, The cylinder liner wherein the outer surface of the cylinder liner has a thermal spray layer only on the tops of the multiple protrusions.

2. A cylinder liner having multiple protrusions on its outer surface, A cylinder liner having a thermal spray coating on the top of each of the multiple protrusions, and elastic material filled between the multiple protrusions.

3. The cylinder liner according to claim 1, wherein an elastic member is filled between the plurality of protrusions.

4. The cylinder liner according to claim 1 or 2, wherein the thermal spray layer is an aluminum alloy thermal spray layer.

5. A joint comprising a cylinder liner having multiple protrusions on its outer surface and a cylinder block joined to the cylinder liner, The outer surface of the cylinder liner is a joint having a thermal spray layer only on the tops of the multiple protrusions.

6. A joint comprising a cylinder liner having multiple protrusions on its outer surface and a cylinder block joined to the cylinder liner, A joint in which the plurality of protrusions have a thermal sprayed layer at their tops, and elastic members are filled between the plurality of protrusions.

7. The joint according to claim 5, wherein an elastic member is filled between the plurality of protrusions.

8. The joint according to claim 5 or 6, wherein the thermal spray layer is an aluminum alloy thermal spray layer.

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