This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2003-193151, filed Jul. 7, 2003, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a cylinder block being cast with cylinder liner which is manufactured by casting a cylinder liner while covering the end-face, a method of manufacturing, and a casting cylinder liner used for the same method.
2. Description of the Related Art
A cylinder block of an engine has been formed by die casting using a light metal such as aluminum alloy. A cylinder block made of aluminum alloy has a defect in wear resistance. To overcome the defect, a cylinder liner is inserted into a cylinder requiring wear resistance. A cylinder liner having a cylindrical shape is made of cast iron, which is cast together with a cylinder block when it is formed by die-casting. For an example, there is a die-casting method disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2000-64902.
In the disclosed method, as shown in
The cylinder block 2 of this type is usually cast by using molds 5a and 5b of a die-casting machine, to cover the end-face 3 of the cylinder head side by aluminum alloy 4, as shown in
In the usual process of casting the cylinder liner 1, a shaft-shaped part 10 that projects downward from the upper mold 5a forming the deck surface side of the cylinder block 2 is inserted into the cylinder liner 1, as shown in
If the position of the inside of the cylinder liner 1 is the same as the position of the end of the upper side projected part 4a covering that end-face, there is no place to hold the cylinder liner 1. Namely, if the whole cylinder liner is to be housed in the cavity formed by the upper mold 5a and lower mold 5b, the cylinder liner cannot be held at a desired position in the upper mold 5a and lower mold 5b for die-casting.
Thus, the inside surface of the cylinder liner 1 used for the overcasting-type cylinder block 2 has the wall thickness projecting to the inside diameter side from the end of the upper side projected part 4a covering the end-face 3 of the deck surface side of the cylinder liner 1, as shown in
Concretely, as shown in
As a result of the hole machining, such as boring or honing in the cylinder liner 1, a hole may be bored at a position displaced from the finished inside diameter dimension position α which is designed. As long as this displacement (a manufacturing error) is within the machining tolerance for a finished product (the dimensional tolerance for a finished liner hole), a certain wall thickness of the cylinder liner 1 is ensured. Therefore, it is no problem to regard the cylinder block 2 as a product completed as designed.
The inside surface of the cylinder liner 1 is machined together with the upper side projected part 4a covering the end-face 3 by boring or honing, as shown in
There is a liner projected type cylinder block, in which a cylinder liner is cast by projecting from a cylinder block. In a cylinder liner used for this type, the inside surface is finished close to the dimension of finished inside diameter in the primary machining process. As the inside surface is formed close to the finished dimension before machining, this cylinder liner can be immediately judged or whether the machining quality is good or bad when displacement exceeding the tolerance range occurs.
In contrast, for the over-casting type cylinder liner 1, a primary machined product that is large in the finished inside diameter dimension α to the inside surface before machining is used to ensure the mold contact part 13. Since this type of cylinder liner 1 is large in the machining margin to the finished dimension, it is possible to complete the hole machining while a displacement exceeding the finished dimensional tolerance is being generated. Thus, the cylinder liner 1 having an extremely thin wall thickness portion may exit in the completed cylinder block 2.
The present invention provides a structure of a cylinder block being cast a cylinder liner, which easily permits detection of displacement exceeding a machining tolerance of a cylinder liner hole without changing a method of manufacturing a cylinder block, a method of manufacturing the cylinder block, and a cylinder liner for casting with a simple structure suitable for detection of displacement.
A cylinder block structure according to the present invention has a cylinder liner. A projected part is formed along a lower end-face of the cylinder liner, and a different level portion that has a predetermined width in the centrifugal direction of the cylinder liner. In this case, the different level portion is formed to be like a circle concentric with the cylinder liner, or at several locations on a circumference of the cylinder liner.
Another cylinder block structure according to the present invention has a cylinder liner cast at a predetermined position of a cylinder block. A projected part is formed along a lower end-face of the cylinder liner. Before a process of machining the internal circumference of the cylinder liner being cast, the projected part has a different level portion having a predetermined width in the centrifugal direction of the cylinder liner. The outside diameter of the different level portion in the radial direction of the cylinder liner is set to the dimension equivalent to the sum of the casting tolerance allowing displacement generated when casing the cylinder liner and the machining tolerance for the machining process, with respect to the finished inside diameter dimension of the cylinder liner.
A method of manufacturing a cylinder block being cast cylinder liner according to the present invention forms a cylinder block by casting a cylindrical cylinder liner at a predetermined position. First, prepare a cylinder liner as a primary product having an annular different level portion with a boundary formed inward in the radial direction by a predetermined dimension, with respect to a finished dimension of an internal circumference of the cylinder liner. Then, set the cylinder liner as a primary product to a holding part that is provided in a mold to form the cylinder block and is fitted with the different level portion. In this state, cast the cylinder block by filling the mold with molten metal. Machine the internal circumference of the cylinder liner to the finished dimension. Detect at least one of a position of the cylinder liner relative to the cylinder block, a position of the cylinder liner hole relative to the cylinder liner, and a wall thickness of the cylinder liner in accordance with whether the different level part exists or not after machining.
A cylinder liner for being cast according to the present invention is cylindrical with an annular different level portion in the end-face. A boundary of the different level portion is formed inside in the radial direction from a machining dimensional tolerance allowed to the finished dimension of the internal circumference of the cylinder liner. The different level portion is provided in both end-faces of the cylinder liner, so that it is unnecessary to specify the direction of the cylinder liner when setting the cylinder liner in a mold.
A method of manufacturing a cylinder block having cylinder liner cast, according to the present invention uses a mold which holds a cylindrical cylinder liner to cast the cylinder liner at a predetermined position of a cylinder block. The mold forms a boundary of an annular different level portion having a width in a radial direction of the cylinder liner along the lower end-face of the cylinder liner by casting. The boundary of the different level portion is provided at a position where is outside of diameter equivalent to a sum of casting tolerance and machining tolerance, with respect to the finished dimension position of the cylinder liner internal circumference. The casting tolerance is the value to allow displacement generated when the cylinder block is cast with the cylinder liner in the mold. The machining tolerance is a tolerance for the finish machining of the internal circumference of the cylinder liner. The finishing of machining the internal circumference of the cylinder liner is operated, after a cylinder block is cast by filling the mold with molten metal. At least one of a displacement of the cylinder liner from the cylinder block, a displacement of a machining position of a hole of the cylinder liner, and a wall thickness of the cylinder liner is detected based on whether the different level portion exists or not.
A structure of a cylinder block according to a first embodiment of the present invention will be explained with reference to drawings
The cylinder liner 20 has a liner body 20a formed cylindrical as a primary product cylinder liner, and a different level portion 21, for holding a mold, formed annular in both end-faces 3 of the liner body 20a. The cylinder liner 20 is made of a high hardness cast iron, for example. The different level portion 21 is formed in the end-face 3 toward the radial direction just like a step. The boundary 21a of the different level portion 21 is provided within the dimensional tolerance range β provided in the internal circumference side, with respect to the finished inside diameter dimension position α of the hole of the cylinder liner 20 indicated by a chain line in the drawing.
The dimensional tolerance range β includes the casting tolerance and machining tolerance. The casting tolerance is a value of displacement allowed when the cylinder liner 20 is cast in the cylinder block 2. The machining tolerance is a value allowed when the internal circumference of the cylinder liner 20 is machined for finishing.
The area located outside in the radial direction from the finished inside diameter dimension position α is a casting area γ that is buried by casting the cylinder block 2. The finished inside diameter dimension position α is provided at the middle in the continued dimensional tolerance range β and casting area γ. The holding part 14 of the upper mold 5a in the deck surface side and the holding part 11 of the lower mold 5b in the opposite side of the deck surface have a shape to fit each other corresponding to the shape of the different level portion 21. The different level portion 21 is a liner holding area ε that comes into contact with the holding parts 11 and 14, respectively.
Next, a method of manufacturing the cylinder block 2 will be explained. As shown in
The upper mold 5a and lower mold 5b are tightened in the state holding the cylinder liner 20, as shown in
In the cylinder block body 2a as a half-finished product of the cast cylinder block 2, the outer circumference of the cylinder liner 20 and an extent of the end-face 3 in the deck surface side consisted the tolerance range β and casting area γ are covered by the aluminum alloy 4, as shown in
Several machining processes are performed to finish the cylinder block body 2a to be a completed cylinder block 2, as shown in
As a result of the hole machining, when the internal circumference of the cylinder liner 20 is finished within the dimensional tolerance range β considering the machining and finished-product, the internal circumference of the cylinder liner 20 is formed flat. Namely, the liner hole 23, which is continued flat without unevenness from the upper side projected part 4a covering the end-face 3 of the cylinder liner 20 to the internal circumference of the cylinder liner 20, is formed.
However, the hole machining for the cylinder liner 20 may be performed exceeding the dimensional tolerance range β, or at a position extremely displaced from the finished inside diameter dimension position α. In this case, as shown in
Therefore, after the hole machining, it can be realized that the finally machined hole (liner hole 23) of the cylinder liner 20 has been machined in being extremely displaced by checking (detecting) visually that the different level portion 21 remains on the deck surface side that becomes the outside of the cylinder block 2 after the hole is machined, and by checking whether the machining marks remains on the internal circumference of the cylinder liner 20. As a result, it can be avoided to include the cylinder liner 20 having an extremely thin portion.
Though it has been considered difficult to improve the manufacturing accuracy of a cylinder block that is cast with the cylinder liner described above, it is easily possible to improve the positional accuracy of the hole of the cast cylinder liner by applying the present invention. Namely, the quality of cylinder block can be improved. Further, it is possible to detect displacement with a high accuracy in the simple structure with the annular different level portion 21 formed in the end-face 3 of the cylinder liner 20. Displacement can be easily detected by checking visually whether the different level 21 remains after machining the internal circumference of the cylinder liner 20.
The different level portion 21 is formed in both end-faces 3 of the cylinder liner 20. Therefore, when a primary product cylinder liner is set in a mold to cast the cylinder block 2, it can be easily set in the mold irrespectively of the direction of the primary product cylinder liner, and the different level portion 21 is arranged in the deck surface side.
According to the embodiment of the present invention explained as above, the boundary 21a of the different level portion 21 taking the finished inside diameter dimension position α of the cylinder liner 20 as a reference is provided at the end portion of the cylinder liner 20 before being cast. Therefore, it is possible to detect extreme displacement of the hole of the cylinder liner 20 by checking whether the different level portion 21 remains after machining the internal circumference of the cylinder liner 20. It is possible to detect displacement of the hole of the cylinder liner 20 with ease without greatly changing the manufacturing method.
According to the cylinder liner 20 of the embodiment of the present invention, it is possible to detect extreme displacement of the hole of the cylinder liner 20 in the simple structure with the different level portion 21 provided at the end portion. According to the embodiment of the present invention with the different level portion 21 provided at both ends of the cylinder liner 20 before being cast, when the cylinder liner 20 is set in the molds 5a and 5b for casting the cylinder block 2, it is unnecessary to specify the setting direction of the cylinder liner 20. Therefore, the setting operation of the cylinder liner 20 in the molds 5a and 5b is lightened, improving the working efficiency.
A second embodiment of the present invention will be described with reference to
A cylinder block 2 of this embodiment has an upper side projected part 4a formed along the upper end-face 3a of a cylinder liner 1, and a lower side projected part 4b formed along the lower end-face 3b, as shown in
The lower side projected part 4b has further a different level portion 31 corresponding to the width of the dimensional tolerance range β. The boundary 31a of the different level portion 31 is provided at the position of the outside edge that becomes the outside diameter of the dimension tolerance range β that is provided in the outer circumference side farther than the finished inside diameter dimension position α. Therefore, as shown in
The upper mold 5a has a shaft-shaped part 10 and a holding part 14. The shaft-shaped part 10 is inserted into the cylinder liner 1, and the lower end comes into contact with the lower mold 5b. The holding part 14 is provided at the base of the shaft-shaped part 10, and comes into contact with the upper end-face 3a of the cylinder liner 1 in the range inside of the casting area γ provided in the upper end-face 3a of the cylinder liner 1. The lower mold 5b has a holding part 11 and a step-forming part 15. The holding part 11 comes into contact with the lower end-face 3b of the cylinder liner 1 in the range of the inside diameter from the inside edge of the dimensional tolerance range β. The step-forming part 15 is provided annularly on the outer circumference of the holding part 11, and has the width corresponding to the dimensional tolerance range β.
The cylinder block 2 is cast with the cylinder liner 1 in the following procedure. First, the cylindrical primary product cylinder liner 1 is held between the upper mold 5a and lower mold 5b for die-casting, as shown in
While the different level portion 21 is provided in the cylinder liner 20 in the first embodiment, the different level portion 31 is provided in the cylinder block 2 in the second embodiment. While the different level portion 21 is eliminated by machining the internal circumference of the cylinder liner 20 in the first embodiment, the different level portion 31 remains after machining the internal circumference of the cylinder liner 1 in the second embodiment. Therefore, it can be easily confirmed by visual inspection after the hole of the cylinder liner 1 is machined that the hole of the cylinder liner 1 of the cylinder block 2 of the second embodiment has been machined at the position nearer to the finished inside diameter dimension position α.
The present invention is not limited to the embodiments described above. The invention may be modified in the scope without departing from the its spirit or essential characteristics.
The technique according to the present invention can be applied not only to a cylinder block in which a cylinder liner is cast. It can also be applied as a technique to cast a bearing liner in a housing in a slide bearing.
Number | Date | Country | Kind |
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2003-193151 | Jul 2003 | JP | national |
This is a Continuation Application of PCT Application No. PCT/JP2004/009987, filed Jul. 7, 2004, which was published under PCT Article 21(2) in Japanese.
Number | Name | Date | Kind |
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6363995 | Baranzke | Apr 2002 | B1 |
Number | Date | Country |
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58-137559 | Sep 1983 | JP |
4-135052 | May 1992 | JP |
04135052 | May 1992 | JP |
2000-64902 | Mar 2000 | JP |
Number | Date | Country | |
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20060108089 A1 | May 2006 | US |
Number | Date | Country | |
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Parent | PCT/JP2004/009987 | Jul 2004 | US |
Child | 11324337 | US |