JP2016223385A - Cylinder block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylinder block capable of improving manufacturing yield.SOLUTION: For a cylinder block 10 for internal combustion engine including a sprayed coating film 12 on a cylinder inner surface, an area ratio Pa of a pit on a surface of the sprayed coating film 12 (bore surface 11a), an effective load roughness Rk of a cross hatch formed on the bore surface 11a and an oil sump depth Rvk of the cross hatch satisfy the following relationship: LOCth≤A×Pa+B×(Rk+Rvk)+C, where LOCth presents an upper value of oil consumption in operation of an internal combustion engine, and A, B and C are a constant number.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a cylinder block.

  In a cylinder block for an internal combustion engine, since a piston reciprocates in a cylinder bore, wear resistance and seizure resistance are required for the inner wall surface (bore surface) of the cylinder bore that comes into contact with the piston. For this reason, conventionally, a sprayed coating of a metal material (for example, an iron-based material) is formed on the cylinder inner surface of a cylinder block made of an aluminum alloy (see, for example, Patent Document 1). The surface of the thermal spray coating that becomes the bore inner surface of the cylinder block is finished as a sliding surface on which the piston slides by honing. On the surface (sliding surface) of the sprayed coating after the honing process, fine crossed grinding marks called cross hatches are formed, and pores formed inside the sprayed coating during the spraying are pits (spraying pits). Appears as These cross hatches and pits hold oil during engine operation.

JP 2009-052132 A

  By the way, if the area ratio (pit ratio) of pits formed on the bore surface of the cylinder bore (the surface of the sprayed coating) or the surface roughness of the bore surface due to cross hatching (cross hatch roughness) increases, Since the amount of oil retained in the pits and cross hatches on the bore surface of the bore increases, there is a concern that the oil consumption will increase. Conventionally, when managing cylinder block products, a good product condition (judgment value) is set for each of the pit ratio and cross hatch roughness of the bore surface of the cylinder bore, and products that do not satisfy any of the good product conditions are rejected. It was judged as a good product. However, such a determination method has a problem that the ratio of products determined to be defective increases, and the manufacturing yield of the cylinder block increases.

  The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide a cylinder block capable of improving the manufacturing yield.

  In the present invention, means for solving the above-described problems are configured as follows. That is, the present invention is a cylinder block for an internal combustion engine in which a spray coating is provided on the cylinder inner surface, and the area ratio Pa of pits on the surface of the spray coating and the cross hatch formed on the surface of the spray coating. The effective load roughness Rk and the oil sump depth Rvk of the cross hatch satisfy the relational expression [LOCth ≦ A × Pa + B × (Rk + Rvk) + C] (where LOCth is the oil during operation of the internal combustion engine) The upper limit of consumption, A, B and C are constants).

  According to the above configuration, the above relational expression based on the oil consumption during operation of the internal combustion engine is used as a non-defective condition of the manufactured cylinder block, so that the pit ratio Pa and the cross hatch on the surface (bore surface) of the sprayed coating Compared with the case where non-defective product conditions are set for each of the roughness [Rk + Rvk] (comparative example), the ratio of products determined as defective products can be reduced, and the manufacturing yield of cylinder blocks can be improved.

  Specifically, in the case of the comparative example, a product that does not satisfy one of the non-defective conditions of the pit ratio Pa of the bore surface and the cross hatch roughness [Rk + Rvk] is determined as a defective product. On the other hand, in the above configuration, even when the pit ratio Pa on the bore surface is relatively large and the non-defective condition of the comparative example is not satisfied, the cross hatch roughness [Rk + Rvk] on the bore surface is relatively small, and the relational expression A product that satisfies the condition is determined to be a non-defective product (see region A12 in FIG. 2). In addition, even when the cross-hatch roughness [Rk + Rvk] of the bore surface is relatively large and the non-defective product condition of the comparative example is not satisfied, a product satisfying the relational expression with a relatively small pit ratio Pa on the bore surface is acceptable. (See area A13 in FIG. 2). As described above, according to the above configuration, since the range in which the cylinder block is determined to be non-defective is expanded as compared with the comparative example, the ratio of products determined to be defective can be reduced. As a result, the manufacturing yield of the cylinder block can be improved, and the productivity of the cylinder block can be improved.

  According to the present invention, the relationship based on the oil consumption during the operation of the internal combustion engine is used as the non-defective condition of the cylinder block to be manufactured. Compared with the case where it sets, the ratio of the product determined to be inferior goods can be reduced, and the manufacturing yield of a cylinder block can be improved.

It is a figure which shows schematic structure of the cylinder block which concerns on embodiment. It is a figure which shows an example of the non-defective product conditions of a cylinder block.

  Hereinafter, an embodiment of a cylinder block to which the present invention is applied will be described with reference to the drawings.

  First, a schematic configuration of a cylinder block according to the embodiment will be described with reference to FIG. As shown in FIG. 1, the cylinder block 10 is, for example, a cylinder block of an in-line four-cylinder engine, and the cylinder block 10 is provided with four cylinder bores 11 arranged in a line. The cylinder block 10 is made of, for example, an aluminum alloy, and is formed by casting. The cylinder bore 11 is formed by the inner wall of the cylinder block 10, and a piston (not shown) is accommodated in the cylinder bore 11.

  An inner wall surface (bore surface) 11a of the cylinder bore 11 is formed by a thermal spray coating 12 made of a metal material (for example, an iron-based metal). That is, the thermal spray coating 12 is formed on the inner wall surface (cylinder inner surface) of the cylinder wall portion provided integrally with the cylinder block 10, and the surface of the thermal spray coating 12 is the bore surface 11 a of the cylinder bore 11. A water jacket 13 is formed on the outer periphery of the cylinder bore 11. The cylinder block 10 is configured as a so-called linerless cylinder block without a cylinder liner.

  A cylinder head is fastened to the upper surface of the cylinder block 10 via a cylinder head gasket (not shown). An oil pan that houses a crankshaft (not shown) and stores engine oil is fastened to the lower surface of the cylinder block 10. The cylinder block 10 only needs to include at least one cylinder bore 11, and may constitute an engine other than the in-line four-cylinder engine.

  Next, the thermal spray coating 12 provided on the cylinder bore 11 of the cylinder block 10 will be described.

  Here, a manufacturing process for manufacturing the cylinder block 10 will be briefly described. The manufacturing process of the cylinder block 10 includes at least a thermal spraying process and a honing process. In the thermal spraying process, a metal material (for example, iron-based metal) is sprayed on the cylinder inner surface of the cylinder block 10 formed by casting or the like to form a thermal spray coating 12 having a predetermined film thickness (diameter width). It is. The honing process is a process of performing a honing process for obtaining a predetermined roundness as a finishing process on the surface of the thermal spray coating 12 adjusted to a predetermined film thickness by a boring process or the like.

  In addition, as a pretreatment for the thermal spraying process, in order to improve the adhesion of the thermal spray coating 12 to the cylinder inner surface of the cylinder block 10, shot blasting or the like for forming minute irregularities on the cylinder inner surface of the cylinder block 10 may be performed. Good. Further, as a pre-process of the honing process, a boring process or the like may be performed in order to control the bore inner diameter of the cylinder block 10 to the bore inner diameter at the machining start point of the subsequent honing process.

  In the cylinder block 10 manufactured as described above, the surface of the sprayed coating 12 is the bore surface 11a. On the surface (bore surface 11a) of the sprayed coating 12 after the honing process, fine crossed grinding streaks called cross hatches are formed, and pores formed inside the sprayed coating 12 at the time of spraying become pits. Is appearing. Oil is held in these cross hatches and pits formed on the bore surface 11a during engine operation.

  By the way, when the pit ratio in the bore surface 11a of the cylinder bore 11 of the cylinder block 10 and the surface roughness (cross hatch roughness) of the bore surface 11a due to cross hatching increase, the pits on the bore surface 11a of the cylinder bore 11 and Since the amount of oil retained in the cross hatch increases, there is a problem that the oil consumption increases due to this. Therefore, in this embodiment, from the viewpoint of suppressing the oil consumption, the pit ratio and the cross hatch roughness of the bore surface 11a of the cylinder bore 11 are set within a predetermined range. Hereinafter, this point will be described.

  During engine operation, the amount of oil retained on the bore surface 11a of the cylinder bore 11 of the cylinder block 10 increases as the pit area ratio (pit ratio) of the bore surface 11a increases, and the cross hatch of the bore surface 11a. The greater the surface roughness, the greater. Specifically, the oil consumption LOC of the bore surface 11a of the cylinder bore 11 during engine operation is expressed by the following relational expression (formula 1) by the pit ratio and the cross hatch surface roughness of the bore surface 11a.

LOC = A × Pa + B × (Rk + Rvk) + C (Formula 1)
However, A, B, and C are constants. This relational expression (formula 1) quantifies the amount of oil consumed in each of the pits and cross hatches of the bore surface 11a, and [A × Pa] [B × (Rk + Rvk)] corresponds to the oil consumption in the cross hatch of the bore surface 11a, corresponding to the oil consumption in the pit of the surface 11a. In the relational expression (Formula 1), Pa is the pit ratio of the bore surface 11a and corresponds to the amount of oil accumulated in the pits of the bore surface 11a. [Rk + Rvk] is the cross-hatch roughness of the bore surface 11a and corresponds to the amount of oil accumulated in the cross-hatch of the bore surface 11a. Rk is the effective load roughness of the cross hatch, and Rvk is the oil sump depth of the cross hatch. C is the oil consumption due to other factors. The constants A, B, and C are values obtained by quantifying data obtained by experiments, simulations, and the like, for example, by multiple regression analysis.
When the relational expression (formula 1) is modified, the following relational expression (formula 2) is obtained.

Rk + Rvk = − (A / B) × Pa + (LOC−C) / B (Formula 2)
In this relational expression (Expression 2), the oil consumption LOC is required to be equal to or less than a predetermined upper limit value (performance limit) LOCth from the engine performance, so the following relational expression (Expression 3) is obtained.

Rk + Rvk ≦ − (A / B) × Pa + (LOCth−C) / B (Formula 3)
In this relational expression (Formula 3), [A / B] and [(LOCth−C) / B] are constants. When the relational expression (formula 3) is modified, the following relational expression (formula 4) is obtained. The relational expression (Formula 4) is equivalent to the relational expression (Formula 3).

LOCth ≧ A × Pa + B × (Rk + Rvk) + C (Formula 4)
The pit ratio Pa and the crosshatch roughness [Rk + Rvk] of the bore surface 11a of the cylinder bore 11 so as to satisfy the relational expression (Expression 3) obtained in this way (or to satisfy the relational expression (Expression 4)). Is set. That is, the pit ratio Pa and the cross hatch roughness [Rk + Rvk] of the bore surface 11a are set based on the upper limit value LOCth of the oil consumption of the bore surface 11a during engine operation.

  According to this embodiment, the relationship (specifically, the relational expression (formula 3)) between the pit ratio Pa of the bore surface 11a and the cross hatch roughness [Rk + Rvk] set based on the oil consumption during engine operation is obtained. It is possible to determine whether the manufactured cylinder block 10 is good. Thereby, compared with the case where non-defective product conditions are set for each of the pit ratio Pa and the cross hatch roughness [Rk + Rvk] of the bore surface 11a, it is possible to reduce the ratio of products determined as defective products. As a result, the manufacturing yield of the cylinder block 10 can be improved, and the productivity of the cylinder block 10 can be improved. This point will be described with reference to FIG.

  The horizontal axis in FIG. 2 is the pit ratio Pa of the bore surface 11a, and the vertical axis is the cross-hatch roughness [Rk + Rvk] of the bore surface 11a. A straight line L1 indicated by a solid line in FIG. 2 corresponds to a case where an equal sign is established in the relational expression (Expression 3). The slope of the straight line L1 is [− (A / B)], which is a coefficient of the pit rate Pa in the relational expression (Expression 3). And the triangular area | region A1 of FIG. 2 is an area | region which satisfy | fills a relational expression (Formula 3).

  The non-defective product determination based on the relational expression (formula 3) is performed by measuring the pit ratio Pa and the cross hatch roughness [Rk + Rvk] of the bore surface 11a of the manufactured cylinder block 10 and measuring the measured pit ratio Pa and the cross hatch roughness [ Rk + Rvk] is performed by determining whether or not Rk + Rvk] is in the area A1 in FIG. That is, the straight line L <b> 1 in FIG. 2 is a non-defective product determination line (determination threshold) for the cylinder block 10. When the measured pit ratio Pa and cross hatch roughness [Rk + Rvk] satisfy the relational expression (Expression 3), the cylinder block 10 is determined to be a non-defective product. On the other hand, when the measured pit rate Pa or cross hatch roughness [Rk + Rvk] does not satisfy the relational expression (formula 3), the cylinder block 10 is determined to be defective. In other words, when the measured pit rate Pa and cross-hatch roughness [Rk + Rvk] are within the area A1 in FIG. 2, the cylinder block 10 is determined to be non-defective. On the other hand, when the measured pit ratio Pa and cross-hatch roughness [Rk + Rvk] are outside the area A1 in FIG. 2, the cylinder block 10 is determined to be defective.

  Here, as a comparative example, consider a case where a non-defective product of the cylinder block 10 is determined based on the pit ratio Pa and the cross hatch roughness [Rk + Rvk] of the bore surface 11a. In this case, the non-defective product determination lines of the cylinder block 10 are, for example, straight lines L2 and L3 shown in FIG. A straight line L2 indicated by a broken line is a straight line parallel to the vertical axis, and a straight line L3 indicated by a one-dot chain line is a straight line parallel to the horizontal axis.

  In the case of the comparative example, the non-defective condition of the cylinder block 10 is [Pa ≦ Pth and Rk + Rvk ≦ Rth], and in FIG. 2, a rectangular region A11 surrounded by the straight lines L2 and L3. Pth is an upper limit value of the pit ratio Pa of the bore surface 11a, and Rth is an upper limit value of the cross hatch roughness [Rk + Rvk] of the bore surface 11a. In the example of FIG. 2, the coordinates (Pth, Rth) are located on the straight line L1.

  In the case of this comparative example, the cylinder block 10 is determined to be non-defective when both the pit ratio Pa of the bore surface 11a and the cross-hatch roughness [Rk + Rvk] are satisfied. On the other hand, if either one of the non-defective conditions of the pit ratio Pa and the cross hatch roughness [Rk + Rvk] of the bore surface 11a is not satisfied, the cylinder block 10 is determined to be defective. In other words, when the pit ratio Pa or the cross hatch roughness [Rk + Rvk] is within the area A11 in FIG. 2, the cylinder block 10 is determined to be a non-defective product. On the other hand, when the pit ratio Pa and the cross hatch roughness [Rk + Rvk] are outside the area A11 in FIG. 2, the cylinder block 10 is determined to be defective.

  On the other hand, in this embodiment, in addition to the area A11 determined as the non-defective product of the comparative example, the triangular areas A12 and A13 in FIG. 2 are also included in the area A1 determined as the non-defective product. The region A12 is [Pa> Pth], but is a region that satisfies the relational expression (Expression 3). The region A13 is [Rk + Rvk> Rth], and is a region that satisfies the relational expression (Expression 3). In this embodiment, as shown by the area A12, even if the pit ratio Pa is relatively large, if the cross hatch roughness [Rk + Rvk] is relatively small, the relational expression (Expression 3) is satisfied, and the cylinder block 10 Is determined to be non-defective. Further, as shown by the area A13, even when the cross hatch roughness [Rk + Rvk] is relatively large, if the pit ratio Pa is relatively small, the relational expression (Expression 3) is satisfied, and the cylinder block 10 is determined to be a good product. It is to be judged.

  As described above, when the pit ratio Pa and the cross hatch roughness [Rk + Rvk] are in the region A12 or the region A13, it is determined as a defective product in the comparative example, whereas in this embodiment, it is determined as a non-defective product. Therefore, according to this embodiment, since the area where the cylinder block 10 is determined to be non-defective is expanded as compared with the comparative example, the ratio of products determined to be defective can be reduced. The manufacturing yield of the block 10 can be improved.

  Embodiment disclosed this time is an illustration in all the points, Comprising: It does not become the basis of limited interpretation. Therefore, the technical scope of the present invention is not interpreted only by the above-described embodiments, but is defined based on the description of the scope of claims. Further, the technical scope of the present invention includes all modifications within the meaning and scope equivalent to the scope of the claims.

  The present invention is applicable to a cylinder block for an internal combustion engine in which a thermal spray coating is provided on the inner surface of the cylinder.

10 Cylinder block 11 Cylinder bore 11a Bore surface 12 Thermal spray coating

Claims (1)

In a cylinder block for an internal combustion engine in which a thermal spray coating is provided on the cylinder inner surface,
The area ratio Pa of the pits on the surface of the thermal spray coating, the effective load roughness Rk of the cross hatch formed on the surface of the thermal spray coating, and the oil sump depth Rvk of the cross hatch are expressed by the following relational expression:
LOCth ≧ A × Pa + B × (Rk + Rvk) + C
(However, LOCth is the upper limit value of oil consumption during internal combustion engine operation, and A, B, and C are constants)
A cylinder block characterized by satisfying

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