JP2022063961A - Method of manufacturing cylinder block - Google Patents

Abstract

To form a heat insulation air layer between a cylinder block and a cylinder liner, when a cylinder block body and the cylinder linear are integrated by a cast-in method.SOLUTION: A method of manufacturing a cylinder block includes a step of performing the machining for suppressing adhesion with an inner peripheral surface of a bore hole formed in a cylinder block body at a desired position on an outer peripheral surface of a cylinder liner, a step of installing the cylinder linear subjected to the machining for suppressing the adhesion, in a mold forming the cylinder block body, a step of supplying molten metal into the mold, a step of solidifying the molten metal, and a step of extracting a cylinder block in which the cylinder block body and the cylinder linear are integrated, from the mold.SELECTED DRAWING: Figure 3

Description

The present invention relates to a method for manufacturing a cylinder block.

Conventionally, a cylinder block included in an internal combustion engine has a cylinder block main body and a tubular cylinder liner assembled in a bore hole formed in the cylinder block main body and integrated with the cylinder block main body. A piston is housed in the cylinder liner so that it can reciprocate along its axial direction. In an internal combustion engine, the air-fuel mixture is burned in a combustion chamber formed in a cylinder head provided in the upper part of the cylinder block. The cylinder liner is heated by the heat of combustion of the air-fuel mixture. Therefore, the temperature of the cylinder liner becomes higher toward the upper part along the axial direction, but smooth sliding of the piston is realized by improving the temperature distribution along the axial direction of the cylinder liner. This is expected to improve fuel efficiency.

In order to improve the temperature distribution along the axial direction of the cylinder liner, for example, it is known to provide an adiabatic air layer between the outer peripheral surface of the cylinder liner and the inner peripheral surface of the bore hole of the cylinder block body ( For example, see Patent Document 1). By providing the adiabatic air layer, heat transfer from the cylinder liner to the cylinder block main body is suppressed, and the temperature distribution in the cylinder liner is improved.

In Patent Document 1, a cylinder liner is press-fitted into a bore hole (cylinder bore) having a recess formed on the inner peripheral surface, and the recess is closed by the outer peripheral surface of the cylinder liner to form a space, and the space is insulated air. It is a layer.

Japanese Unexamined Patent Publication No. 2005-330873

By the way, in recent years, in order to integrate the cylinder block main body and the cylinder liner, a casting and wrapping method is known in which a cylinder liner is installed in a mold for casting the cylinder block main body and molten metal is poured into the mold in this state. .. By using the casting and wrapping method, the cylinder liner and the cylinder block main body can be easily integrated. However, when the casting and wrapping method is used, it is difficult to form a recess in the bore hole, and it is difficult to form a heat insulating air layer between the cylinder block main body and the cylinder liner in a state of being integrated. In Patent Document 1, the cylinder liner is fitted into the cylinder block main body by press fitting, and it is not assumed that both are integrated by using the casting and wrapping method.

Therefore, in the method for manufacturing a cylinder block disclosed in the present specification, when the cylinder block main body and the cylinder liner are integrated by the casting and wrapping method, a heat insulating air layer is formed between the cylinder block main body and the cylinder liner. Make it an issue.

The method for manufacturing a cylinder block disclosed in the present specification includes a step of performing a process of suppressing adhesion to the inner peripheral surface of a bore hole formed in the cylinder block main body at a desired position on the outer peripheral surface of the cylinder liner, and the above-mentioned. A step of installing the cylinder liner processed to suppress adhesion in a mold forming the cylinder block main body, a step of supplying molten metal into the mold, a step of solidifying the molten metal, and the mold. It includes a step of taking out a cylinder block in which the cylinder block main body and the cylinder liner are integrated from the inside.

According to the method for manufacturing a cylinder block disclosed in the present specification, when the cylinder block main body and the cylinder liner are integrated by the casting and wrapping method, an insulated air layer can be formed between the cylinder block main body and the cylinder liner. can.

FIG. 1 is an explanatory diagram showing a schematic configuration of an internal combustion engine including a cylinder block manufactured by the method of manufacturing a cylinder block of the embodiment. FIG. 2A is a diagram schematically showing an example of a casting apparatus used in the method for manufacturing a cylinder block of the embodiment, and FIG. 2B is a state in which a cylinder liner is installed in a mold of the casting apparatus. It is a diagram schematically showing, and FIG. 2C is a diagram schematically showing a state in which a molten metal is injected into a mold. FIG. 3 is a flowchart showing an example of a method for manufacturing a cylinder block according to an embodiment. FIG. 4 is a perspective view of a cylinder liner cast and wrapped in the cylinder block in the method of manufacturing the cylinder block of the embodiment. 5 (A) to 5 (C) are explanatory views schematically showing the outer peripheral surface of the cylinder liner subjected to the anchor processing. FIG. 6A is a graph showing an example of the distribution of the cylinder liner temperature along the bore height direction in the cylinder block manufactured by the manufacturing method of the embodiment, and FIG. 6B is a graph showing the bore height in the cylinder block. It is a graph which shows an example of the transition of the clearance between the inner peripheral surface of a cylinder liner and a piston along a direction. FIG. 7 is a diagram showing an adiabatic air layer formed between the cylinder block main body and the cylinder liner.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, in the drawings, the dimensions, ratios, etc. of each part may not be shown so as to completely match the actual ones. Also, depending on the drawing, details may be omitted.

(Embodiment)
[Cylinder block]
The present embodiment relates to a method for manufacturing a cylinder block 1, but in order to make the manufacturing method easier to understand, first, an example of the cylinder block 1 manufactured by this manufacturing method is given prior to a detailed description thereof. Will be explained.

Referring to FIG. 1, in the cylinder block 1 included in the internal combustion engine 50, a cylindrical cylinder liner 15 is mounted in a bore hole 11 formed in the cylinder block main body 10. The cylinder block main body 10 in the cylinder block 1 of the present embodiment is made of cast aluminum, but other conventionally known materials may be used. Although the cylinder liner 15 is made of cast iron, another material may be used as long as it is a material having better wear resistance than the aluminum forming the cylinder block main body 10.

An open deck type water jacket 12 is provided on the upper edge of the cylinder block main body 10. A piston 20 is slidably housed in the cylinder liner 15 along the axis AX direction of the cylinder liner 15. Although the cylinder and piston for one cylinder are shown in FIG. 1, the internal combustion engine 50 of the present embodiment is an in-line 4-cylinder internal combustion engine, and includes four cylinders and pistons along the vertical direction of the paper. The number of cylinders of the internal combustion engine to which this embodiment can be applied is not limited to four cylinders, and may be another number of cylinders. Further, the arrangement method is not limited to the series, and may be a conventionally known arrangement method such as V type.

A cylinder head 25 is mounted on the upper side of the cylinder block 1. The cylinder head 25 is provided with an intake port 25a to which an intake valve 26a is attached and an exhaust port 25b to which an exhaust valve 26b is attached. Further, the cylinder head 25 is provided with a combustion chamber 27. A spark plug 28 is provided in the combustion chamber 27.

In FIG. 1, the piston 20 is drawn by a dotted line, and a state where the piston 20 is located at the top dead center and a state where the piston 20 is located at the bottom dead center are drawn. The piston 20 includes a skirt portion 21, and the height from the upper end of the piston 20 to the lower end of the skirt portion 21 is h. Here, when the piston 20 is at top dead center, the height position where the lower end of the skirt portion 21 is located, that is, the height position separated downward from the upper end of the piston 20 at top dead center by a distance h. Let it be P1. Further, when the piston 20 is at bottom dead center, P2 is a height position where the lower end of the skirt portion 21 is located, that is, a height position separated downward by a distance h from the upper end of the piston 20 at bottom dead center. And.

The cylinder block 1 is provided with an adiabatic air layer 18 between the inner peripheral surface 11a of the bore hole 11 and the outer peripheral surface 151 of the cylinder liner 15 and in the range from the height position P1 to the height position P2. There is.

The cylinder liner 15 includes a first portion 15a, a second portion 15b, and a third portion 15c in this order from above. The adiabatic air layer 18 is formed in a portion corresponding to the second portion 15b, and in the first portion 15a and the third portion 15c, the inner peripheral surface 11a of the bore hole 11 and the outer peripheral surface 151 of the cylinder liner 15 are in close contact with each other. are doing. The surfaces of the first portion 15a and the third portion 15c are processed so that the inner peripheral surface 11a of the bore hole 11 and the outer peripheral surface 151 of the cylinder liner 15 can be easily brought into close contact with each other. This processing will be described later.

The combustion heat generated in the combustion chamber 27 is transmitted to the cylinder liner 15. In the first portion 15a and the third portion 15c, which are in close contact with the inner peripheral surface 11a of the bore hole 11, the heat stored in the cylinder liner 15 is transferred to the cylinder block main body 10. As a result, the temperature of the cylinder liner 15 drops in the first portion 15a and the third portion 15c. On the other hand, in the second portion 15b, since the adiabatic air layer 18 exists between the cylinder block main body 10 and the cylinder block main body 10, heat transfer from the cylinder liner 15 to the cylinder block main body 10 is suppressed, and the cylinder liner 15 is suppressed. The temperature is maintained. A water jacket 12 is provided around the first portion 15a. The first portion 15a near the combustion chamber 27 and its surroundings become hot, but are cooled by the cooling water flowing in the water jacket 12.

[Production method]
Next, a method for manufacturing the cylinder block 1 will be described with reference to FIGS. 2 (A) to 5 (C).

First, with reference to FIG. 2A, a schematic configuration of a casting apparatus 100 used for manufacturing the cylinder block 1 will be described. FIG. 2A is a cross-sectional view schematically showing the casting apparatus 100. The casting apparatus 100 can integrally form the cylinder block main body 10 and the cylinder liner 15 by the casting and wrapping method. The casting device 100 includes a fixed mold 101 and a movable mold 102. The fixed mold 101 and the movable mold 102 form a space 103 having an inner peripheral shape corresponding to the shape of the cylinder block main body 10 in a combined state. One end of the runner 106 is connected to the space 103. The other end of the runner 106 is connected to the cylinder 105a included in the injection portion 105. A piston 105b is slidably provided in the cylinder 105a. A decompression passage 107 communicating with the outside of the combined fixed mold 101 and the movable mold 102 is connected to the space 103. The casting device 100 shown in FIG. 2A is an example, and the casting device 100 for carrying out the manufacturing method of the embodiment is not limited to this, and the holding posture of the cylinder liner 15 and the direction of mold clamping (movable). The moving direction of the mold 102), the material of the mold, and the like can be appropriately selected and changed.

Next, a method of manufacturing the cylinder block 1 will be described with reference to the flowchart shown in FIG. First, in step S1, a mold release agent is applied to a portion of the fixed mold 101 and the movable mold 102 shown in FIG. 2A in contact with the molten aluminum M (see FIG. 2C). Further, in step S2, a cylinder liner 15 that has been subjected to predetermined processing is prepared. Regardless of the order of the steps of step S1 and step S2, both steps may be completed before the step of step S3 is performed.

Here, the processing of the cylinder liner 15 performed in step S2 will be described in detail. The cylinder liner 15 is formed in advance by a casting process using cast iron. The casting process of this embodiment uses a centrifugal casting method. Referring to FIG. 4, the outer peripheral surface 151 of the cylinder liner 15 includes a first portion 15a, a second portion 15b, and a third portion 15c in this order from above. As described with reference to FIG. 1, the first portion 15a is a portion where the inner peripheral surface 11a of the bore hole 11 and the outer peripheral surface 151 of the cylinder liner 15 are in close contact with each other. Referring to FIG. 5A, a large number of anchor protrusions 16a are provided on the outer peripheral surface 151 of the cylinder liner 15. The anchor convex portion 16a has a mushroom shape having an umbrella-shaped portion having a larger diameter than the proximal end side on the distal end side. The anchor convex portion 16a exerts an anchor effect of improving the biting property of the cylinder liner 15 to the cylinder block main body 10. As a result, the adhesion between the inner peripheral surface 11a of the bore hole 11 and the outer peripheral surface 151 of the cylinder liner 15 in the first portion 15a is improved. The anchor convex portion 16a is also provided in the third portion 15c shown in FIG. 4, and the adhesion between the inner peripheral surface 11a of the bore hole 11 and the outer peripheral surface 151 of the cylinder liner 15 in the third portion 15c is improved. Will be. The anchor convex portion 16a in the present embodiment is formed on the outer peripheral surface 151 of the cylinder liner 15 at the time of casting the cylinder liner 15 by adopting the centrifugal casting method. Since a conventionally known method can be applied to the centrifugal casting method capable of forming the anchor convex portion 16a, detailed description thereof will be omitted here.

The anchor convex portion 16a may have another shape as long as it can improve the adhesion between the inner peripheral surface 11a of the bore hole 11 and the outer peripheral surface 151 of the cylinder liner 15. For example, the anchor convex portion 16b having a truncated cone shape shown in FIG. 5B may be used. The anchor convex portion 16b is provided so that the large diameter side of the truncated cone is located on the tip side. Further, as shown in FIG. 5C, the anchor recess 16c may be adopted. The inner diameter of the anchor recess 16c is larger than the inlet diameter, so that the adhesion between the bore hole 11 and the cylinder liner 15 can be improved. Further, the outer peripheral surface 151 of the cylinder liner 15 may be provided with a cylindrical or prismatic convex portion, a circular or rectangular concave portion, or the outer peripheral surface 151 may have a rough surface.

In this way, the first portion 15a and the third portion 15c, which have been processed to exert an anchor effect for improving the biting property of the cylinder liner 15 to the cylinder block main body 10, are in close contact with the second portion 15b. Inhibitor is applied. In FIG. 4, the hatched portion schematically shows the state in which the adhesion inhibitor is applied. The adhesion inhibitor is applied to the second portion 15b of the outer peripheral surface 151 of the centrifugally cast cylinder liner 15. The second portion 15b is set according to the position where the insulated air layer 18 shown in FIG. 1 is formed. The application of the adhesion inhibitor to the second portion 15b is an example of processing for suppressing the adhesion between the outer peripheral surface 151 of the cylinder liner 15 and the inner peripheral surface 11a of the bore hole 11. In the present embodiment, oil is selected as the adhesion inhibitor, and the oil is applied to the second portion 15b. The adhesion inhibitor is required to disappear when it comes into contact with the molten aluminum M. Since the molten aluminum M used in this embodiment has a temperature of about 600 ° C., a substance having the property of being degreased and disappearing in this temperature range is adopted. The adhesion inhibitor can be appropriately selected from oils, greases and the like having such properties.

After the process of step S1 and the process of step S2 are completed, the process proceeds to step S3. In step S3, the cylinder liner 15 is installed between the fixed mold 101 and the movable mold 102 as shown in FIG. 2 (B). The cylinder liner 15, which is a tubular member, has a fixed mold 101 and a movable mold 102 in a state where a holding core 104a is attached to one open end and a holding pin 104b is attached to the other open end. It is installed between and.

Then, in step S4, the movable mold 102 is brought closer to the fixed mold 101 to perform mold clamping. After the mold is fastened in step S4, as shown in FIG. 2C, the molten aluminum M is supplied into the cylinder 105a of the injection portion 105 (step S5), and the piston 105b is further operated to operate the aluminum. The molten metal M is injected (step S6).

The injected aluminum molten metal M is filled in the space 103. Since the air in the space 103 is discharged to the outside through the decompression passage 107, the molten aluminum M flows smoothly into the space 103 and reaches every corner. The filled aluminum molten metal M also reaches the periphery of the cylinder liner 15 installed in the space 103. In the first portion 15a and the third portion 15c, the molten aluminum M is in contact with the outer peripheral surface 151 of the cylinder liner 15. Further, the molten aluminum M also enters the periphery of the anchor convex portion 16a shown in FIG. 5 (A). On the other hand, in the second portion 15b (see FIG. 4), the inner peripheral surface 11a of the bore hole 11 and the outer peripheral surface 151 of the cylinder liner 15 are coated due to the application of oil which is an adhesion inhibitor. Adhesion is hindered.

Then, in the solidification step of step S7, in the first portion 15a and the third portion 15c, the molten aluminum M in contact with the outer peripheral surface 151 of the cylinder liner 15 solidifies, so that the cylinder liner 15 is integrated with the cylinder block main body 10. Will be done. At this time, the molten aluminum M that has entered the periphery of the anchor convex portion 16a solidifies, so that the inner peripheral surface 11a of the bore hole 11 and the outer peripheral surface 151 of the cylinder liner 15 in the first portion 15a and the third portion 15c are strengthened. It will be in a state of being combined with.

On the other hand, in the second portion 15b, the inner peripheral surface 11a of the bore hole 11 and the outer peripheral surface 151 of the cylinder liner 15 do not come into close contact with each other, and the insulated air layer 18 as shown in FIG. 1 is formed. The adhesion inhibitor applied to the second portion 15b is degreased by the heat of the molten aluminum M in the process of solidifying the molten aluminum M.

When the solidification of the molten aluminum M is completed, the mold opening (step S8) is subsequently performed. Then, the cylinder liner 15 is cast into the cylinder block main body 10 from the fixed mold 101 and the movable mold 102, and the rough material of the cylinder block 1 in an integrated state is extruded (step S9). Then, the cylinder block 1 can be obtained through a molding step (step S11) in which the rough material is taken out (step S10) and burrs are removed.

In the manufacturing method of the present embodiment, adhesion to the inner peripheral surface 11a of the bore hole 11 formed in the cylinder block main body 10 at a desired position on the outer peripheral surface 151 of the cylinder liner 15 to be cast and wrapped in the cylinder block main body 10 is suppressed. Processing is applied. As a result, the adiabatic air layer 18 can be formed at a desired position even when the casting and wrapping method is adopted.

Here, with reference to FIGS. 6 (A) to 7 (A), it is shown that the adiabatic air layer 18 capable of obtaining a predetermined effect is formed on the cylinder block 1 by the manufacturing method of the embodiment. 6 (A) and 6 (B) show a cylinder block 1 in which the adiabatic air layer 18 is formed by the manufacturing method of the embodiment and a cylinder block in which the adiabatic air layer is not provided.

FIG. 6A is a graph showing an example of the distribution of the cylinder liner temperature along the bore height direction. Further, FIG. 6B is a graph showing an example of the transition of the clearance between the inner peripheral surface of the cylinder liner and the piston along the bore height direction. In each graph, the vertical axis is the bore height direction in the cylinder block, the "upper part" on the vertical axis corresponds to the first portion 15a, and the "middle portion" corresponds to the second portion 15b. Further, the "lower part" corresponds to the third portion 15c.

Referring to FIG. 6A, no large temperature difference was observed between the cylinder block not provided with the adiabatic air layer and the cylinder block 1 manufactured by the manufacturing method of the embodiment in the upper part and the lower part. On the other hand, in the central part, the cylinder liner temperature of the cylinder block 1 of the embodiment is higher than the cylinder liner temperature of the cylinder block having no adiabatic air layer. This is because, in the cylinder block 1 of the embodiment, the adiabatic air layer 18 as shown in FIG. 7 is formed in the central portion (second portion 15b), and the heat transfer from the cylinder liner 15 to the cylinder block main body 10 is suppressed. This is because the heat remains in the cylinder liner 15.

Reflecting such a temperature distribution, there is also a difference in the clearance between the inner peripheral surface of the cylinder liner and the piston between the cylinder block 1 according to the manufacturing method of the embodiment and the cylinder block not provided with the adiabatic air layer. There is. That is, in the upper part and the lower part, there is no significant difference in clearance between the cylinder block 1 of the embodiment and the cylinder block not provided with the adiabatic air layer, but in the central part, there is a difference in clearance between the two. In the central part of the cylinder block 1 of the embodiment in which the adiabatic air layer 18 is provided, the temperature of the cylinder liner 15 is high. Therefore, in the central portion (second portion 15b), the peripheral length of the annular cylinder liner 15 becomes long, and as a result, the clearance between the inner peripheral surface of the cylinder liner and the piston becomes large. In the present embodiment, as shown in FIG. 1, the adiabatic air layer 18 is provided in the range from the height position P1 to the height position P2. The height position P1 to the height position P2 are included in the range in which the piston 20 slides. Therefore, the sliding friction of the piston 20 in the range where the adiabatic air layer 18 is provided is reduced. As a result, improvement in fuel efficiency is expected. As described above, it can be seen that the adiabatic air layer 18 formed by the manufacturing method of the embodiment is functioning.

At the lower part in the bore height direction, the clearance between the inner peripheral surface of the cylinder liner and the piston is kept narrow. As a result, it is suppressed that the engine oil reaches the piston ring mounted on the piston 20, and the consumption of the engine oil is suppressed.

In the present embodiment, the first portion 15a and the third portion 15c are provided with the anchor convex portion 16a and the like shown in FIG. 5A, and further, the outer peripheral surface 151 of the cylinder liner 15 and the inner peripheral surface of the bore hole 11 are provided. An adhesion inhibitor is applied to suppress adhesion. By applying the adhesion inhibitor, the adhesion between the outer peripheral surface 151 of the cylinder liner 15 and the inner peripheral surface of the bore hole 11 can be effectively suppressed.

However, in order to suppress the adhesion between the outer peripheral surface 151 of the cylinder liner 15 and the inner peripheral surface 11a of the bore hole 11, the application of the adhesion inhibitor is not essential, and the application of the adhesion inhibitor may be omitted.

In short, the outer peripheral surface 151 of the cylinder liner 15 cast and wrapped in the molten metal forming the cylinder block main body 10 may be in a state where adhesion with the inner peripheral surface 11a of the bore hole 11 is suppressed at a desired position. ..

For example, the surface roughness of the second portion 15b whose adhesion with the inner peripheral surface 11a of the bore hole 11 is desired to be brought into close contact with the inner peripheral surface 11a of the bore hole 11 is the surface roughness of the first portion 15a and the third portion 15c. It may be a mode to keep it smoother than that. In this case, even if the adhesion inhibitor is not applied to the second portion 15b, the adhesion of the bore hole 11 to the inner peripheral surface 11a is suppressed in the second portion 15b whose surface is smooth, and the adiabatic air layer 18 is formed. Will be done. In this way, the adiabatic air layer 18 can be formed by providing a difference between the state of the surface of the second portion 15b and the state of the surface of the first portion 15a and the third portion 15c.

Further, even if there is no difference in the surface roughness of the first portion 15a, the second portion 15b and the third portion 15c, the adhesion inhibitor is applied only to the second portion 15b forming the adiabatic air layer 18. , Casting may be performed. The adiabatic air layer 18 can be formed even in such an embodiment.

The above-described embodiment is merely an example for carrying out the present invention, the present invention is not limited thereto, and various modifications of these examples are within the scope of the present invention, and further, the present invention. It is self-evident from the above description that various other embodiments are possible within the scope.

1 Cylinder block 10 Cylinder block body 11 Bore hole 11a Inner peripheral surface of bore hole 12 Water jacket 15 Cylinder liner 15a 1st part 15b 2nd part 15c 3rd part 16a, 16b Anchor convex part 16c Anchor concave part 18 Insulated air layer 20 Piston 21 Cylinder head 25 Cylinder head 50 Internal combustion engine 100 Casting equipment 101 Fixed mold 102 Movable mold 103 Space 104a Holding core 104b Holding pin 105 Injection part 106 Channel 107 Decompression passage 151 Cylinder liner outer peripheral surface M Aluminum molten metal

Claims (1)

A process of performing processing to suppress adhesion to the inner peripheral surface of the bore hole formed in the cylinder block body at a desired position on the outer peripheral surface of the cylinder liner, and
The process of installing the cylinder liner, which has been processed to suppress adhesion, in the mold forming the cylinder block main body, and
The process of supplying molten metal into the mold and
The step of coagulating the molten metal and
The process of taking out the cylinder block in which the cylinder block main body and the cylinder liner are integrated from the mold, and
A method for manufacturing a cylinder block including.

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