JPS63248543A - Cylinder liner and its production - Google Patents

Abstract

PURPOSE:To prevent the development of flash, etc., in a cylinder liner and to efficiently produce the cylinder liner having excellent sizing accuracy by integrately forming cylinder part and plural projections protruding to outside from the outer circumference of the cylinder part. CONSTITUTION:The cylinder liner 20 is constituted the cylinder part 22 having thin thickness and plural number of first projection parts 24, which are protrusively formed toward outside on the outer circumference of the cylinder part 22, and plural number of second projection parts 26, which the length is shorter than that of the first projection part 24. Next, an expendable pattern for the cylinder liner 20 is formed by foaming beads of foaming polystyrene, etc. Therefore, plural number of first hole parts 34a-34f corresponding to the first projection parts 24 and plural number of second hole parts 36a-36f corresponding to the second projection parts 26 of the cylinder liner 20, are bored. Further, the cylinder liner 20 is cast and formed by using the expendable pattern through forming device 28.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a cylinder liner that is cast into a cylinder block constituting an engine, and a method for manufacturing the same, and more particularly, the present invention relates to a cylinder liner that is cast into a cylinder block that constitutes an engine, and a method for manufacturing the cylinder liner. The present invention relates to a cylinder liner that can be easily manufactured with high precision by molding a fugitive model, melting and dissolving the fugitive model with molten metal, and casting.

[Prior Art] In general, a ring block that constitutes an engine of an automobile or the like is cast from an aluminum alloy or the like in order to reduce the weight of the entire engine.

For this reason, in the cylinder block, a cylinder liner made of cast iron or the like having excellent wear resistance is cast around the portion on which the piston slides.

By the way, in this case, since the cylinder liner and the cylinder block are made of different materials, there is a risk that the adhesion between the cylinder liner and the cylinder block may deteriorate during engine operation due to the difference in their respective coefficients of thermal expansion. occurs. Furthermore, since the piston slides within the cylinder liner at high speed, vibrations are generated within the engine, resulting in reduced adhesion between the cylinder liner and the cylinder block, resulting in rattling.

Therefore, various types of cylinder liners have been proposed in the past in which a plurality of protrusions or irregularities are formed on the outer circumference of the cylinder liner in order to firmly adhere the cylinder liner to the cylinder block.

For example, JP-A No. 60-118352 discloses a method of manufacturing a cylinder liner having a plurality of protrusions on the outer periphery.

That is, as shown in FIG. 1, a casting model 2 is used in the conventional method. The model 2 includes a semi-cylindrical wooden mold 4, and a plurality of cylindrical protrusions 6 made of an elastic soft material such as rubber are provided on the outer peripheral surface of the wooden mold 4.

Therefore, using the model 2, a cylinder liner is manufactured and molded by a vacuum casting method. That is, in Figure 2,
The first molding frame 8a is filled with foundry dry sand 10a. In this case, by leading the air inside the first molding frame 8a to the outside from the air intake port 12a formed in the first molding frame 8a, the air inside the first molding frame 8a can be drawn through the plastic film 14a. A first cavity 16a corresponding to the shape of the model 2 is defined.

On the other hand, the second molding frame 8b is the first molding frame 8 described above.
It is formed in the same manner as a, and the same reference numerals are given the same reference numerals and the suffix b is attached to the same components, and detailed explanation thereof will be omitted.

Next, the respective molding frames 8a and 8b are joined together,
A cylindrical core 18 is provided in each cavity 16a, 16b.
to be placed. Furthermore, after pouring the molten metal into the cavities 16a and 16b, suction action from the respective intake ports 12a and 12b is started.

Therefore, if the cavities 16a, 16 are cooled for a predetermined time,
The molten metal is solidified within b, and a metal cylinder liner having a plurality of protrusions on the outside is cast.

However, in the prior art described above, as shown in FIG. 2, molten metal is injected into the respective cavities 16a and 16b while the first molding frame 8a and the second molding frame 8b are joined. For this reason, in particular, each molding frame body 8a, 8b
It is easy for flash to form at the joints of the parts, and it is necessary to remove the flash after casting is completed. Therefore, with this kind of cylinder liner provided with an external protrusion, a considerable amount of time is required to manufacture the cylinder liner, and the protrusion makes the removal operation extremely troublesome.

Moreover, in the above-described casting method, the cavities 16a, 1
A core 18 is disposed within 6b. In this case, since the cylinder liner is molded to be relatively thin, even if the position of the core 18 is slightly shifted, the thickness of the cylinder liner becomes uneven, and the cylinder liner becomes a defective product.

For this reason, the positioning of the core 18 must be performed with high precision, which imposes a considerable burden on the operator and is inconvenient in that the efficiency of the entire cylinder liner casting operation cannot be achieved.

Furthermore, after the cylinder liner is cast through the respective molding frames 8a and 8b, it is necessary to take out the core 18 from the cylinder liner. Therefore, generally, the outer circumferential surface of the core 18 is formed into a tapered shape, and this core 18
Work is underway to extract it from the large diameter end. As a result, a taper hole is formed in the cylinder liner, and it takes time and effort to process this taper hole into a desired hole, which exposes the disadvantage that the manufacturing process of the cylinder liner is complicated. do.

[Problems to be Solved by the Invention] The present invention has been made in order to overcome the above-mentioned disadvantages, and is directed to solving the problem of dissipation of a cylinder liner made of a foamed material such as foamed plastic and provided with a plurality of protrusions on the outer periphery. By molding a model, then burying the model in a sand mold, and performing casting by disappearing the model using a full mold casting method, the generation of unnecessary parts such as casting holes can be prevented as much as possible, and It is an object of the present invention to provide a cylinder liner that has excellent dimensional accuracy without using a core, and that can be manufactured easily and efficiently, and a method for manufacturing the cylinder liner.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a cylinder liner that is cast into a cylinder block constituting an internal combustion engine, which includes a cylindrical portion and a cylinder liner that extends from the outer periphery of the cylindrical portion. It is characterized in that it is integrally formed with a plurality of protrusions that bulge in the opposite direction, and that at least the protrusion on the combustion chamber side has a larger surface area than the protrusion on the crank chamber side.

Furthermore, the present invention provides a method for manufacturing a cylinder liner that is cast into a cylinder block constituting an internal combustion engine, in which a plurality of protrusions are provided on the outer peripheral surface using a material that disappears with poured molten metal. The method is characterized in that a fugitive model for the cylinder liner is molded, and then the model is placed in a casting mold, molten metal is poured into the mold, and the model is melted and disappeared to cast a metal cylinder liner. .

[Embodiments] Next, preferred embodiments of the cylinder liner and the manufacturing method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 3, reference numeral 20 designates a cylinder liner according to the invention. In this case, the cylinder liner 20
a thin cylindrical portion 22; a plurality of first protrusions 24 formed to bulge outward on the outer peripheral surface of the cylindrical portion 22; and a plurality of first protrusions 24 shorter than the first protrusions 24. 2 protrusion 2
It basically consists of 6.

The first protrusions 24 are oriented in the axial direction from the end surface 22a of the cylindrical portion 22, and are provided in a lattice or houndstooth pattern at predetermined intervals. At this time, the end surface 22a of the cylindrical portion 22 corresponds to the gasket surface, and a position spaced apart by the length from the end surface 22a corresponds to the bottom dead center of the piston (not shown). And the cylindrical part 22
Short second protrusions 26 are arranged in a lattice or houndstooth pattern in the same manner as described above on the remaining outer peripheral portion spaced apart from the end surface 22a by the length L or more.

In this embodiment, the first protrusion 24 and the second protrusion 26 having two different lengths are employed. For example, the first protrusion 24 and the second protrusion 26 have two different lengths. It may be configured by providing a plurality of protrusions that reduce the length.

Next, FIG. 4 shows a molding apparatus for molding a fugitive model of the cylinder liner 20 using foamed beads such as foamed polystyrene or foamed urethane.

That is, the molded jlif 28 includes a plurality of movable molds 30a to 30f, and the movable molds 30a to 30f are configured to move forward and backward in the direction of the arrow under the driving action of an actuator (not shown). Arcuate surfaces 32a to 32f are formed on the inner surfaces of the movable dies 30a to 30f, respectively.
A plurality of first holes 34a to 34 corresponding to the protrusion 24
f and a plurality of second holes 36a corresponding to the second projections 26
36f to 36f are drilled. Therefore, the movable molds 30a to 3
When the mold 0f is clamped, each movable mold 30a to 30f
Inside are arcuate surfaces 32a to 32f8 and first holes 34a to 3.
4f and the second holes 36a to 36f define a space 38 corresponding to the shape of the outer peripheral surface of the cylinder liner 20. Further, a cylindrical core 40 is disposed within this space 38 in correspondence with the inner circumferential surface of the cylindrical portion 22 of the cylinder liner 20.

Further, the cylinder liner 20 is cast by using the fugitive model molded by the molding device 28, but in this case, the casting method is the generally popular full mold casting method. shall be adopted. Therefore, a casting mold used in the full mold casting method is schematically shown in FIG.

That is, in the figure, reference numeral 42 indicates a casting mold;
This casting mold 42 includes a frame 44 shaped like a housing.

A fugitive model 46 and a fugitive passageway 48 formed by the above-described molding device 28 are embedded in the frame 44 via molding sand 50. Note that the evanescent passage 48 consists of a sprue portion 52) a runner portion 54 and dish portions 56a and 56b,
Like the fugitive model 46, it is integrally molded using a foam material, and the plate portions 56a, 56b are adhered to the fugitive model 46.

The cylinder liner and the apparatus for carrying out the manufacturing method thereof according to the present invention are basically constructed as described above, and the functions and effects thereof will be explained next.

First, the fugitive model 46 is molded using the molding device 28 . That is, under the action of an actuator (not shown), the movable molds 30a to 30'' are displaced in a direction closer to each other and the molds are clamped, and the core 40 is placed in the space 38 defined within the movable molds 30a to 30f. Therefore, three foam beads made of foamed polystyrene or foamed urethane are used.
The space 38 defined in the molding device 28 is filled with a filling pressure of 5 kg/csM to 5 kg/ca.

Next, the air in the space 38 is led out to the outside under the action of a suction device (not shown), and the inside of the space 38 is heated to a predetermined temperature via steam or the like, thereby forming the fugitive model 46.

Furthermore, the movable molds 30a to 30f are released, and the molding device 2
A similarly shaped fugitive passage 48 is fixed to the fugitive model 46 taken out from 8. Then, the fugitive model 46 and the fugitive passage 48 are integrally arranged in a frame 44 constituting the casting mold 42, and the frame 44 is filled with molding sand 50.

Next, when molten metal such as Fe12 is poured into the sprue 52 of the fugitive passage 48, the sprue 52 is melted by the molten metal, and the molten metal flows into the runner 54 side. Further, via this runner part 54, the dish parts 55a, 56b
The molten metal that has reached this level further melts the fugitive model 46, and this fugitive model 46 is replaced by the molten metal.

Therefore, after cooling for a predetermined period of time, the cylinder liner 20 and the unnecessary portion molded to replace the fugitive passage 48 are integrally cast in the casting mold 42.

Therefore, from this cylinder liner 20, each plate portion 56 is
By cutting and removing unnecessary portions molded corresponding to a and 56b, the desired cylinder liner 2° can be obtained.

In this case, according to the present invention, since the cylinder liner 20 is cast by a full mold casting method through the fugitive model 46, the cylinder liner 20 can be molded with high precision, and the cylinder liner 20 can be molded with high precision.
It becomes possible to simplify the post-processing of 0.

That is, when casting and molding the cylinder liner 2o, the conventional core is not required, so the troublesome work of positioning the core is freed, and the cylinder liner 20 can be cast and molded efficiently. I can do it. Moreover, unlike in the case of using a core, a tapered hole is not formed in the cylindrical portion 22, and therefore, it is possible to form a desired hole in the cylindrical portion in an iris shape. .

Furthermore, in the method of the present invention, since the cylinder liner 20 is cast through a single fugitive model 46, no casting holes or the like are formed on the cylinder liner 20.
Post-processing of the cylinder liner 20 is simplified at once. In this case, essentially, unnecessary portions that are integrally formed on the outer circumferential portion of the cylinder liner 20 at positions corresponding to the dish portions 56a and 56b may be removed from the cylinder liner 20.

Note that the fugitive model 46 is integrally molded using a molding device 28, but for example, after molding each part of the fugitive model 46 using a plurality of molding devices, each part is bonded. It is also possible to form a single fugitive model 46 by using the same method.

Furthermore, the cylinder liner 20 has an elongated first cylinder on its outer peripheral surface over a length range from the end surface 22a corresponding to the gasket surface to the bottom dead center position of the piston.
A plurality of protrusions 24 are provided, and a plurality of second protrusions 26 shorter than the second protrusions 26 are formed in other parts. Therefore, the adhesion between the cylinder liner 20 and the cylinder block in which it is cast is further improved, and the cylinder liner 20 is prevented from being partially thermally strained during engine operation.
wear can be reduced as much as possible.

That is, FIG. 6 shows the temperature of the cylinder bore during engine operation in relation to the distance from the crank chamber side, where the solid line A shows the temperature curve of the conventional cylinder liner, and the broken line B shows the temperature curve of the conventional cylinder liner. A temperature curve of the cylinder liner 20 is shown. In this case, as a conventional cylinder liner, a cylinder liner in which a plurality of protrusions of the same length are provided on the outer circumference is used.

As can be easily understood from the figure, in the conventional cylinder liner, especially when the distance from the crank chamber side is 80 or more, that is, in the range from the bottom dead center of the piston to the gasket surface side, the cylinder bore The temperature is rising rapidly.

Therefore, a considerably large temperature difference occurs in the axial direction of the cylinder liner, causing local thermal strain and the like in the cylinder liner, resulting in significant wear between the cylinder liner and the piston.

On the other hand, in the cylinder liner 20 according to the present invention, a relatively long first protrusion 24 is provided within the distance from the bottom dead center of the piston to the gasket surface, and a second protrusion 24 that is shorter than this is provided in other parts. A protrusion 26 is formed. Therefore, in the cylinder liner 20, the surface area exposed to the outside from the end surface 22a to the bottom dead center of the piston is larger than the surface area of other parts, and the cooling effect within the sliding range of the piston is better than other parts. become. As a result, the cylinder liner 20 has a substantially uniform temperature distribution over the entire cylinder bore, as shown by the broken line B in FIG. , it becomes possible to avoid the occurrence of wear as much as possible.

Further, the cylinder liner 20 generally has a seventh
As shown in the figure, a plurality of units are arranged in the cylinder block 60,
It is set up. Therefore, in the first protrusions 24 of each cylinder liner 20, the first protrusions 2 facing each other
If 4a to 24C are selected to be shorter than the other first projections 24, the intervals between the respective cylinder liners 20, that is,
The distance S between the bores can be shortened. As a result, it is possible to easily downsize the entire engine into which the cylinder block 60 is incorporated.

[Effects of the Invention] As described above, according to the present invention, when manufacturing a cylinder liner having a plurality of protrusions on the outer periphery, first, a fugitive model corresponding to the cylinder liner is created using a foam material. Then, the cylinder liner is cast through the fugitive model by a full mold casting method.

Therefore, during casting, there is no need to use a core as in the past, and variations in wall thickness due to misalignment of the core can be avoided, and a tapered hole is formed in the cylinder liner. Never. Furthermore, since the cylinder liner is integrally cast using a single fugitive model, it is possible to prevent molding from occurring in the cylinder liner. As a result, it is possible to easily and efficiently manufacture a cylinder liner with excellent dimensional accuracy.

Moreover, on the outer circumference of the cylinder liner, a plurality of relatively long first protrusions are provided at positions corresponding to the sliding range of the piston, and a plurality of short second protrusions are provided in other parts. A bulge is forming. Therefore, during engine operation, the heat generated in the range from the gasket surface to the bottom dead center of the piston can be effectively radiated to the outside through the long protrusion, and the heat can be evenly distributed over the entire cylinder liner. It becomes possible to secure the temperature and avoid occurrence of local thermal distortion.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments.
Of course, various improvements and changes in design are possible without departing from the gist of the present invention.

[Brief explanation of drawings]

1 and 2 are explanatory diagrams of a casting model and a molding frame for carrying out a method for casting a cylinder liner according to the prior art; FIG. 3 is a schematic perspective view of a cylinder liner according to the present invention; The figure is a partial cross-sectional schematic perspective view of a fugitive model molding apparatus for implementing the cylinder liner manufacturing method according to the present invention, FIG. 5 is a schematic perspective view of a casting mold for implementing the present invention method, Figure 6 is a relationship diagram showing the temperature state of the cylinder bore during engine operation between the cylinder liner according to the prior art and the cylinder liner according to the present invention, and Figure 7 is a part of a cylinder block in which the cylinder liner according to the present invention is cast. FIG. 20... Cylinder liner 22... Cylindrical part 24
．． 26... Projection 28... Molding device 38
...Space part 42...Casting mold 46...
・Disappearance model 4th...Disappearance passage FIG,
2 Cylinder bore temperature

Claims (6)

[Claims] (1) A cylinder liner cast into a cylinder block constituting an internal combustion engine, which is integrally formed from a cylindrical part and a plurality of protrusions bulging outward from the outer periphery of the cylindrical part, and A cylinder liner characterized in that at least a protrusion on the combustion chamber side has a larger surface area than a protrusion on the crank chamber side. (2) In the cylinder liner according to claim 1, a plurality of first protrusions are provided over a predetermined length in the axial direction from the combustion chamber side end of the cylindrical part, and further the first protrusions A cylinder liner comprising a plurality of second protrusions that are shorter than the first protrusions and are directed toward the crank chamber. (3) In the cylinder liner according to claim 1, the protrusion is configured to gradually become shorter from the end on the combustion chamber side of the cylindrical portion to the end on the crank chamber side. liner. (4) In the cylinder liner according to claim 2 or 3, when a plurality of cylinder liners are cast into the cylinder block, each adjacent cylinder liner has at least one or more opposing protrusions in a predetermined manner. A cylinder liner that is made shorter in length. (5) A method for manufacturing a cylinder liner that is cast into a cylinder block constituting an internal combustion engine, the cylinder liner having a plurality of protrusions on its outer circumferential surface using a material that disappears with poured molten metal. Molding a vanishing model,
Next, the method for manufacturing a cylinder liner is characterized in that the model is disposed in a casting mold, molten metal is poured into the mold, the model is melted and dissolved, and a metal cylinder liner is cast. (6) A method for manufacturing a cylinder liner according to claim 5, in which the fugitive model is substantially molded from foamed plastic.