JP2007056793A - Cylinder block and manufacturing method for cylinder block - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder block having a novel structure requiring no masking tool when forming a thermal spraying coating on a wall face of a bore. <P>SOLUTION: This cylinder block 10 is provided with a shielding wall 40 protruding in the direction along the wall face 20 of the cylinder bore from an opening fringe part 32 of the cylinder bore to prevent thermal spraying particles jetted from an injection port 54' of a thermal spraying gun 52' from adhering to an inner face 30 of a skirt part 14 when spraying thermally on the wall face 20 of the cylinder bore. In a casting process, the masking tool becomes unnecessary by casting the shielding wall 40 integrally because thermal spraying particles jetted in the thermal spraying process do not reach the opening fringe part 32 of the cylinder bore and the inner face 30 of the skirt part in a condition in which they are not completely cooled and do not adhere to these sections incompletely. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cylinder block of an engine, and more particularly to a structure of a cylinder block in which a sprayed coating is formed on a cylinder bore wall surface.

  A cylinder block is a main structural member of a reciprocating engine (hereinafter simply referred to as “engine”) such as an internal combustion engine. A cylinder bore is formed in the cylinder block, and a piston reciprocates in the cylinder bore. The cylinder bore wall surface is slid by this piston. For this reason, the cylinder bore wall surface (hereinafter referred to as “bore wall surface”) is required to have wear resistance.

  By the way, an aluminum alloy is often used for the material of the cylinder block in order to reduce the engine weight. However, the aluminum alloy has a problem of low wear resistance as compared with conventionally used cast iron. For this reason, in a conventional aluminum alloy cylinder block, a cast cylinder made of cast iron is inserted, and the inner surface of the cast iron cylinder liner is used as a bore wall surface to satisfy the required wear resistance. Yes.

  However, in recent years, in order to further reduce the size and weight of the engine, there is a demand for the cylinder block to be a so-called “monoblock” that does not use a cylinder liner. In this case, the bore wall surface needs to be treated to satisfy the required wear resistance.

  Therefore, we apply a technology to form a thermal spray coating on the cylinder block by spraying a fine powder of the thermal spray material in a molten state (hereinafter referred to as thermal spray particles), and apply an iron thermal spray coating on the bore wall surface of the aluminum cylinder block. It is conventionally known to form. The thickness of this iron sprayed coating is much thinner than that of a cast iron cylinder liner, but the wear resistance required for the bore wall surface can be ensured.

  Therefore, when using a sprayed coating of iron to ensure wear resistance, the bore pitch (distance between the axes of adjacent cylinder bores) is the same as the bore diameter compared to using a cast iron cylinder liner. As a result, the engine can be further miniaturized.

  When the spray coating is formed on the bore wall surface as described above, a spray gun for spraying spray particles is inserted into the cylinder bore, and spray particles are sprayed while rotating around the cylinder bore axis while rotating the cylinder bore. Reciprocate along the axis.

  In this case, in order to uniformly form the spray coating up to the end of the cylinder bore wall surface, it is necessary to move the spray gun to the end of the bore. At this time, a part of the thermal spray material protrudes from the outer side of the bore and is sprayed, and adheres to a site where it is not necessary to form the thermal spray coating. The upper end side of the bore, that is, the side on which the cylinder head is mounted is not a problem because it will be machined later. However, the protruding thermal spray particles adhere to the inner surface of the crankcase on the lower end side of the bore.

  If the protruding and attached portion is located sufficiently far from the spray gun injection port, the sprayed particles will not cool and will not adhere to the inner surface of the crankcase. However, the spray particles are incompletely attached to a portion at a distance where the spray particles are not completely cooled. In such an incompletely attached state, the sprayed particles may drop later and circulate inside the engine as impurities in the engine oil, which may wear the sliding surface or bearing surface. .

  The following Patent Document 1 discloses a jig that shields protruding thermal spray particles from the outside of the bore so that the protruding thermal spray particles do not adhere to the inner surface of the crankcase. That is, at the time of thermal spraying, a cylindrical jig is installed at the bore opening edge on the crankcase side. Since the spray particles protruding from the lower end side of the bore are sprayed on the inner wall surface of the jig, the spray particles can be prevented from adhering to the inner surface of the crankcase.

JP-A-6-65711

  However, if the above-described thermal spraying process is repeated several times, the thermal spray particles are stacked on the inner wall of the masking tube and cannot be used as a jig. In order to continue to use this masking tube, it is necessary to cut off the sprayed material laminated on the inner wall every few times by cutting.Thus, it takes a lot of man-hours to maintain the jig, which increases the manufacturing cost of the cylinder block. It is a factor to increase. Therefore, there is a demand for a new method that does not require a jig for masking.

  Therefore, an object of the present invention is to provide a cylinder block having a novel structure that does not require a masking jig in forming a thermal spray coating on the cylinder bore wall surface, and a manufacturing method for manufacturing the cylinder block.

  The cylinder block of the present invention is a shielding wall that protrudes in a direction along the cylinder bore wall surface from the edge of the cylinder bore opening so as to prevent spray particles sprayed from adhering to the inner surface of the skirt portion when spraying onto the cylinder bore wall surface. It is equipped with. The shielding wall shields thermal spray particles that reach the inner surface of the skirt portion and adhere incompletely without being cooled down.

  Preferably, the shielding wall is provided at a predetermined height in the direction along the cylinder bore wall surface from the edge of the cylinder bore opening, and surrounds the cylinder bore opening together with a bulkhead provided so as to protrude from between adjacent cylinder bores in the direction along the cylinder bore wall surface. Is formed.

  Preferably, the inner surface of the shielding wall is inclined so as to expand the cylinder bore radial direction outward as the distance from the cylinder bore increases in the direction along the cylinder bore wall surface.

  Preferably, the inclination angle of the inner surface of the shielding wall is 10 to 45 °.

  Another cylinder block of the present invention includes a bulkhead and a wall protruding in a direction along the cylinder bore wall surface from the cylinder bore opening edge so as to surround the cylinder bore opening at a predetermined height.

  The cylinder block manufacturing method of the present invention shields spray particles by projecting in the direction along the cylinder bore wall surface from the cylinder bore opening edge so that the spray particles sprayed onto the cylinder bore wall surface do not adhere to the inner surface of the skirt portion in the casting process. The shielding wall is cast as one piece. The shielding wall formed in this casting process shields the sprayed particles in the subsequent spraying process.

  According to the cylinder block of the present invention, it is possible to manufacture a cylinder block in which a spray coating is formed on the wall surface of the cylinder bore without requiring a masking jig when spraying the cylinder bore.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. In the present embodiment, as an example, a cylinder block of an in-line four-cylinder engine having a bore diameter of 80 mm and a bore pitch of 88 mm will be described. However, the present invention is not limited to this embodiment, and is applicable not only to engines of other dimensions but also to cylinder blocks of internal combustion engines such as inline engines other than four cylinders, V-type engines and horizontally opposed engines. Can also be applied. The present invention can be applied to any cylinder block that constitutes a reciprocating engine, such as an external combustion engine or a piston reciprocating air compressor, as well as an internal combustion engine.

  The structure of the cylinder block 10 of this embodiment is demonstrated using FIGS. 1-3. 1 shows a cross-sectional view of the cylinder block 10, FIG. 2 shows a cross-sectional view of the cylinder block 10 along the line AA in FIG. 1, and FIG. 3 shows a direction indicated by an arrow B in FIG. The bottom view of the cylinder block 10 seen from FIG. The cylinder block 10 mainly includes a cylinder part 12 in which a cylinder bore 16 is formed, a skirt part 14 constituting a part of a crankcase for accommodating a crankshaft (not shown), and the inside of the crankcase for each cylinder. And a bulkhead 26 for partitioning. The cylinder part 12, the skirt part 14, and the bulkhead 26 are integrally formed by casting.

  As shown in FIG. 1, a cylinder bore 16 that is a cylindrical hole is formed in the cylinder portion 12. The axis of the cylinder bore 16 is indicated by a one-dot chain line E in FIGS. 1 and 2 and by a point E in FIG. A portion surrounding the cylinder bore 16 of the cylinder portion 12 is a cylinder wall 18. A piston (not shown) that reciprocates in the cylinder bore 16 slides in the cylinder bore 16 in contact with a wall surface 20 (hereinafter referred to as a bore wall surface 20) of the cylinder bore 16 shown in FIG. In order to prevent wear due to this sliding, a sprayed coating is formed on the bore wall surface 20 in a spraying process to be described later.

  A cylinder head (not shown) is mounted on a so-called upper deck 18a side of the cylinder bore 16 of the cylinder wall 18, and a combustion chamber is formed by the cylinder bore 16, the piston, and the cylinder head. A coolant passage 24 (water jacket) through which coolant circulates is formed inside the cylinder wall 18, and cools the cylinder portion 12 and the combustion chamber to an optimum temperature.

  On the other hand, as shown in FIG. 2, the cylinder wall 18 protrudes in the direction along the bore wall surface 20 (indicated by an arrow D) from the lower end 16b side of the cylinder bore 16, and the bulk that partitions the crankcase for each cylinder. A head 26 is provided. The bulkhead 26 is formed with a journal receiving portion 28 for receiving a crankshaft journal (not shown).

  Note that the axis of the journal of the crankshaft (hereinafter referred to as the crankshaft) is indicated by a point C in FIG. 1 and a dashed-dotted line C in FIG. The crankshaft is mounted on the cylinder block 10 by placing the crankshaft on the journal receiving portion 28 and fixing the bearing cap and the bearing beam to the bulkhead 26.

  Further, the cylinder block 10 is provided with a skirt portion 14 that connects the plurality of bulkheads 26 and constitutes the outer shell of the crankcase. As shown in FIG. 1, the skirt portion 14 is formed integrally with the cylinder wall 18 of the cylinder portion 12, and the inner surface 30 of the skirt portion 14 is an opening on the cylinder bore lower end 16 b side (the side on which the crankshaft is mounted). From the edge 32, it is provided so as to extend in the direction perpendicular to the crankshaft center C and the radial direction of the cylinder bore 16 outward (direction indicated by arrow F in the figure).

  A lower block, an oil pan, a crank oil seal, and the like are attached to the lower end 34 of the skirt portion 14. Together with these components, the skirt portion 14 can constitute a crankcase and accommodate the crankshaft.

  Further, as shown in FIG. 1, the cylinder block 10 has a predetermined height (indicated by an arrow in FIG. 1) from the cylinder bore opening edge 32 (bore lower end side) toward the crankshaft in the direction D along the bore wall surface 20. A protruding shielding wall 40 (shown as X) is provided. This shielding wall 40 is formed integrally with the above-described cylinder portion 12, bulkhead 26, and skirt portion 14 in the process of casting the cylinder block 10.

  As shown in FIGS. 2 and 3, the shielding wall 40 is formed so as to surround the opening of the cylinder bore 16 together with the bulkhead 26 protruding in the direction D along the bore wall surface 20 from between the adjacent cylinder bores 16. As shown in FIG. 3, the shielding wall 40 is formed in an arc shape along the cylinder bore opening 36, and both ends of the arc shape are on both sides in the direction along the crankshaft axis C with the cylinder bore 16 axis E interposed therebetween. Are connected to a substantially straight bulkhead 26. In other words, the inner surface of the shielding wall 40 and the inner surface of the bulkhead 26 surround the cylinder bore opening 36 in a shape in which both sides of the circular shape are cut off linearly.

  As shown in FIG. 2, the height at which the bulkhead 26 protrudes in the direction D along the bore wall surface 20 from the bore lower end 16 b is larger than the height X of the shielding wall 40. That is, the inner surface of the shielding wall 40 surrounds the cylinder bore opening 36 over a predetermined height X together with the bulkhead inner surface 26b. In the cylinder block 10 of the present embodiment, the height X of the shielding wall 40 is set to 10 mm.

  Further, as shown in FIG. 1, the inner surface 40 b of the shielding wall 40 is inclined so as to expand the cylinder bore radial direction outward (direction indicated by the arrow F in the drawing) as the distance from the cylinder bore 16 increases in the direction D along the bore wall surface 20. ing. The inclination angle θ of the shielding wall inner surface 40b is preferably 10 to 45 ° with respect to the direction D along the bore wall surface 20, and is set to 25 ° in the cylinder block 10 of the present embodiment.

  The shielding wall 40 described above is integrally formed in the process of casting the cylinder block 10, and then sprayed out of the cylinder bore lower end 16b in the spraying process of spraying spray particles onto the wall surface of the cylinder bore 16 to form a sprayed coating. It has a function of shielding the particles from adhering to the inner surface 30 of the skirt portion. Details of the function will be described later.

  Next, the manufacturing method of the cylinder block 10 of this embodiment is demonstrated. FIG. 4 shows a state in which the spraying gun is inserted into the cylinder bore in the cylinder block 10 of the present embodiment to perform the spraying process, and FIG. 5 shows a spraying gun inserted into the cylinder bore in the conventional cylinder block 100. And the state which is performing the thermal spraying process is shown.

  First, the cylinder block 10 having the above-described configuration is cast. In this casting process, the cylinder block 10, the skirt part 14, and the bulkhead 26 are integrally cast with the shielding wall 40 that shields the sprayed particles protruding from the cylinder bore lower end 16b in the subsequent spraying process. The Since the shielding wall 40 that shields the spray particles in the casting process is integrally formed, it is not necessary to attach a masking jig in the subsequent spraying process.

  Then, the bore wall surface 20 is machined. In this machining process, first, the machining is performed using a machining device or the like to cut the bore wall surface 20 with the cast surface exposed to make the cylinder bore 16 have a predetermined diameter. After that, shot blasting is performed on the bore wall surface 20 by blowing a blast material to roughen the surface. By providing unevenness on the bore wall surface 20, the spray coating formed in the subsequent spraying process is easily held on the bore wall surface 20.

  Then, the thermal spray coating 50 is formed by spraying the thermal spray particles onto the cylinder bore wall surface 20. As shown in FIG. 4, a spray gun 52 for injecting spray particles is inserted into the cylinder bore 16 along the bore axis E, and the spray particles obtained by melting the spray material together with the carrier gas from the injection port 54 through the bore axis. Injects in a direction perpendicular to the heart. The spray particles sprayed are spread at a predetermined angle α (hereinafter referred to as a spray frame angle α) and sprayed to the bore wall surface 20 as shown by a broken line in FIG. As the sprayed particles in the molten state that have reached and adhered to the bore wall surface 20 are cooled and solidified, a sprayed coating 50 having a thickness of about 0.1 mm is formed on the portion of the bore wall surface 20 to which the sprayed particles have been sprayed.

  While spraying onto the bore wall surface 20 as described above, the spray gun 52 is reciprocated along the bore axis E while rotating around the bore axis E. By spraying the spray gun 52 back and forth so that the spray port 54 protrudes from the bore upper end 16a and the bore lower end 16b at a predetermined moving speed while rotating the spray gun 52 at a predetermined rotational speed, a uniform spray coating on the entire bore wall surface 20 is achieved. 50 can be formed.

  However, when the above-described thermal spraying process is applied to the cylinder block 100 having a conventional structure without using a masking jig, the thermal spray particles are incompletely adhered to the cylinder bore opening edge 32 and the skirt inner surface 30. End up. As shown by a two-dot chain line in FIG. 5, when spraying particles are sprayed from a position where the spray port 54 of the spraying gun 52 protrudes from the cylinder bore lower end 16 b, the sprayed sprayed particles spread as shown by a broken line in the figure, It reaches the cylinder bore opening edge 32 and the inner surface 30 of the skirt.

  The thermal spray particles that have reached the cylinder bore opening edge 32 adhere to and stack. However, the cylinder bore opening edge portion 32 is farther from the injection port 54 than the bore wall surface 20, and in addition, the angle at which the sprayed particles that have reached the surface of the opening edge portion 32 is an acute angle compared to the bore wall surface 20. Therefore, the thermal spray particles laminated here are attached in an incomplete state.

  On the other hand, on the inner surface 30 of the skirt portion, there are a portion 62 where the sprayed particles reach without being cooled and a portion 64 where the sprayed particles reach when cooled. The part 62 that reaches without being completely cooled is a part adjacent to the cylinder bore opening edge 32, and the spray particles are incompletely adhered thereto. On the other hand, the portion 64 that reaches in the cold state is a portion that is farther from the injection port 54 than the portion 62 that reaches in the cold state. , Will not adhere.

  As described above, in the conventional cylinder block 100, when the thermal spraying process is performed without using the masking jig, the thermal spray particles are incompletely attached to the cylinder bore opening edge 32 and the skirt inner surface 30 adjacent thereto. The part 32 and 62 which will end up will arise. Thus, when the cylinder block 100 vibrates from the portions 32 and 62 where the spray particles are incompletely adhered, there is a problem that the laminate of the spray particles peels off and easily drops off.

  The cylinder block 10 according to the present embodiment has been developed by paying attention to such a problem, so that spray particles injected in the spraying process do not adhere to the cylinder bore opening edge 32 and the skirt portion inner surface 30. In the casting process, a shielding wall 40 that projects from the cylinder bore opening edge 32 in the direction D along the bore wall surface 20 toward the crankshaft is integrally cast on the cylinder block 10. If the shielding wall 40 is not provided, the shielding wall 40 reaches the cylinder bore opening edge 32 and the skirt inner surface 30 in a state where the shielding wall 40 is not completely cooled, and shields spray particles that are incompletely attached to these portions.

  In the case of the cylinder block 10 of the present embodiment, when the spray gun 52 ′ is moved so that the spray port 54 protrudes from the cylinder bore 16, as shown by a two-dot chain line in FIG. The sprayed particles thus reached not only the bore wall surface 20 but also the shielding wall inner surface 40b and the part 68 of the skirt portion inner surface 30.

  Since the shielding wall inner surface 40b is substantially the same distance as the cylinder bore wall surface 20 from the injection port 54 ', the sprayed spray particles reach the shielding wall inner surface 40b in a sufficiently melted state. Therefore, the sprayed particles are completely adhered to the shielding wall inner surface 40b, and the sprayed coating 58 is formed. The sprayed particles (sprayed coating 58) that are completely adhered in this way are not dropped even when the cylinder block 10 vibrates.

  On the other hand, the portion 68 of the skirt portion inner surface 30 where the spray particles reach is at a relatively far distance from the injection port 54 ′, so that the sprayed spray particles reach the portion 68 in a cold state. Therefore, although the thermal spray particles come into contact with the portion 68, they do not adhere.

  With respect to these portions, the cylinder bore opening edge portion 32 on the back side (the outer side in the bore radial direction) of the shielding wall inner surface 40b and the portion 66 adjacent to the cylinder bore opening edge portion 32 in the skirt portion inner surface 30 Since the spray particles are shielded by 40, the spray particles do not reach.

  As described above, the cylinder block 10 according to the present embodiment is provided with the shielding wall 40 that protrudes from the cylinder bore opening edge 32 in the direction along the cylinder bore wall surface 20 and shields the spray particles. Even without using the thermal spraying particles, the sprayed particles do not incompletely adhere to the cylinder bore opening edge portion 32 or the skirt portion inner surface 30.

  The length X of the shielding wall 40, that is, the length X (see FIG. 1) at which the shielding wall 40 projects in the direction along the bore wall surface 20 from the cylinder bore opening edge 32 is a direction orthogonal to the crankshaft center C. The distance L (shown in FIG. 5) between the boundary G (shown in FIG. 5) between the incompletely attached portion 62 and the non-attached portion 64 in the radial direction of the cylinder bore 16 and the cylinder bore wall surface 20 is injected. Based on the thermal spray frame angle α of the thermal spray particles, it is set so as to satisfy the formula of X> L × tan (α / 2). Here, the distance L, that is, the boundary G, is obtained experimentally by actually performing a thermal spraying process by inserting a thermal spray gun into the cylinder bore 16 using the cylinder block 100 having the same dimensions except for the shielding wall 40. It is done. In this embodiment, the spray frame angle of the spray gun 52 used in the spraying process is 30 °, and the distance L between the boundary G and the cylinder bore wall surface 20 is 30 mm. Is set to 10 mm.

  In addition, after obtaining the coordinates of the boundary G by the above-described experiment, the length of the shielding wall 40 can be set by the following method. For example, as shown in FIG. 6, the spray gun 52 is inserted in the direction D along the bore wall surface 20 until the sprayed particles sprayed from the spray port 54 do not reach the boundary G, and the sprayed particles sprayed on the cylinder bore side. The shape and dimensions of the shielding wall 40 are set so that the tip 40c contacts the contour 70.

  Further, in the cylinder block 10 of the present embodiment, the shielding wall 40 surrounds the opening of the cylinder bore 16 with the predetermined height X together with the bulkhead 26. As shown in FIG. 3, the bulkhead inner surface 26b is closer in distance from the bore axis E than the shielding wall inner surface 40b. Therefore, in the thermal spraying process, the sprayed spray particles arrive in a sufficiently melted state. Therefore, similarly to the shielding wall inner surface 40b, since the spray particles completely adhere to the bulkhead inner surface 26b, the spray particles adhered from here do not fall off. In other words, the shielding wall 40 of the present embodiment can shield the bore opening 36 “over the entire circumference” so that the sprayed particles protruding from the cylinder bore lower end 16 b together with the bulkhead 26 do not reach the inner surface 30 of the skirt portion. .

  In addition, after the above-mentioned spraying process, it is necessary to honing the sprayed coating 50 on the bore wall surface 20. In the honing process, a cylindrical polishing jig is inserted into the cylinder bore 16 and reciprocated along the bore axis E while rotating around the bore axis E. Thereby, the thermal spray coating 50 on the bore wall surface 20 is polished.

  However, in the above-described thermal spraying process, the thermal spray coating is formed not only on the bore wall surface 20 but also on the shielding wall inner surface 40b. If the shielding wall inner surface 40b has a continuous structure without being inclined with respect to the bore wall surface 20, if only the thermal spray coating 50 on the bore wall surface 20 is honed, the thermal spray coating 50 and the honing on the bore wall surface 20 after machining are honed. A step is generated between the thermal spray coating 58 on the inner surface 40b of the shielding wall that is not processed. Such a step is not preferable because the piston skirt may come into contact with the step. In order to eliminate such a step, in the honing process, it is necessary to perform not only the sprayed coating 50 on the bore wall surface 20 but also the sprayed coating 58 on the shielding wall inner surface 40b. That is, the area for performing the honing process is increased.

  Therefore, in the cylinder block 10 of the present embodiment, the shielding wall inner surface 40b is inclined at an angle of 10 ° or more with respect to the bore wall surface 20 so as to expand the bore radial direction outward. That is, the thermal spray coating 58 on the inner surface 40b of the shielding wall escapes outward in the bore radial direction with respect to the thermal spray coating 50 on the bore wall surface 20.

  Thus, when the thermal spray coating 50 on the bore wall surface 20 is honed, the thermal spray coating 58 on the inner surface 40b of the shielding wall can be obtained even if the polishing jig is reciprocated along the bore axis E so as to protrude from the cylinder lower end 16b. The sprayed coating 50 on the bore wall surface 20 after processing and the sprayed coating 58 on the shielding wall 40 that is not honed are connected without causing any step without contact with the polishing jig.

  Therefore, even if the cylinder block 10 of this embodiment provides the shielding wall 40 which shields a thermal spray particle and performs a thermal spraying process with the bore | wall wall surface 20, in the subsequent honing process, the thermal spray coating 58 on the shielding wall 40 is honed. There is no need to process. There is no effect of increasing the area to be subjected to honing, and the manufacturing cost for honing does not increase.

  Moreover, in the cylinder block 10 of this embodiment, it is preferable that the shielding wall inner surface 40b is inclined at an angle of 45 ° or less with respect to the bore wall surface 20 so as to expand the bore radial direction outward. On the contrary, if this inclination angle is set to 45 ° or more, not only the distance from the injection port 54 to the shielding wall inner surface 40b is increased in the thermal spraying process, but also the sprayed sprayed particles hit the shielding wall inner surface 40b. Since the angle becomes an acute angle as compared with the bore wall surface 20, there is a possibility that the sprayed particles adhere incompletely. If the inclination angle is 45 ° or less, the sprayed particles that have reached the shielding wall inner surface 40b can be completely adhered.

  As described above, the cylinder block 10 according to the present embodiment includes the shielding wall 40 that protrudes from the cylinder bore opening edge 32 in the direction along the cylinder bore wall surface 20 and shields the spray particles. The spray particles do not adhere to the inner surface of the skirt portion in an incomplete state. For this reason, a cylinder block having a sprayed coating formed on the wall surface of the cylinder bore can be manufactured without requiring a masking jig when spraying the cylinder bore. As a result, the cost for manufacturing the cylinder block can be reduced.

It is a transverse cross section of a cylinder block of this embodiment, and is a figure showing a state before a sprayed coating is formed on a bore wall surface. It is a longitudinal cross-sectional view of the cylinder block of this embodiment, and is sectional drawing by the AA line of FIG. It is a bottom view of the cylinder block of this embodiment, and is a figure seen from the direction shown by arrow B in FIG. It is a figure which shows the thermal spraying process of the cylinder block of this embodiment, and is a figure which shows the state which inserts the thermal spray gun in a cylinder bore and performs the thermal spraying process on the bore | boa wall surface. It is a figure which shows the conventional thermal spraying process of a cylinder block, and is a figure which shows the state which inserts a thermal spray gun in a cylinder bore and performs a thermal spraying process on the bore | boa wall surface. It is a figure which shows an example of the setting method of the shielding wall in the cylinder block of this embodiment.

Explanation of symbols

  10 cylinder block, 12 cylinder section, 14 skirt section, 16 cylinder bore, 20 bore wall surface, 26 bulkhead, 30 inner skirt section, 32 cylinder bore opening edge, 36 bore opening, 40 shielding wall, 50 spray coating, 52 spray gun, 54 Injection port, 100 cylinder block.

Claims (6)

A cylinder portion formed with a cylinder bore;
A skirt portion that is integrally provided so as to expand from the cylinder bore opening edge of the cylinder portion, and constitutes a part of the crankcase;
A cylinder block having
When spraying on the cylinder bore wall surface, the sprayed particles sprayed from the cylinder bore opening edge in the direction along the cylinder bore wall surface to shield the spray particles so that the spray particles to be sprayed do not adhere to the inner surface of the skirt portion,
A cylinder block with a sprayed coating on the cylinder bore wall. The cylinder block according to claim 1,
The shielding wall is provided at a predetermined height in the direction along the cylinder bore wall surface from the edge of the cylinder bore opening, and is formed so as to surround the cylinder bore opening together with a bulk head provided so as to protrude from between adjacent cylinder bores in the direction along the cylinder bore wall surface. Yes,
Cylinder block. The cylinder block according to claim 2,
The inner surface of the shielding wall is inclined so as to expand the cylinder bore radial direction outward as it moves away from the cylinder bore in a direction along the cylinder bore wall surface.
Cylinder block. The cylinder block according to claim 3,
The inclination angle of the inner surface of the shielding wall is 10 to 45 °.
Cylinder block. A cylinder portion formed with a cylinder bore;
A skirt portion that is integrally provided so as to expand from the cylinder bore opening edge of the cylinder portion, and constitutes a part of the crankcase;
A bulkhead provided to protrude in a direction along the cylinder bore wall surface from between adjacent cylinder bores;
A cylinder block having
A wall projecting in a direction along the cylinder bore wall surface from the cylinder bore opening edge so as to surround the cylinder bore opening at a predetermined height together with the bulkhead.
Cylinder block. A casting step of integrally casting a cylinder block having a cylinder portion in which a cylinder bore is formed and a skirt portion that extends from the cylinder bore opening edge of the cylinder portion and forms a part of the crankcase;
Machining process for machining the cylinder bore wall surface;
A spraying step of spraying spray particles onto the cylinder bore wall surface to form a sprayed coating;
A cylinder block manufacturing method comprising:
In the casting process, a shielding wall that projects from the cylinder bore opening edge in the direction along the cylinder bore wall surface and shields the spray particles is integrally cast so that the spray particles sprayed onto the cylinder bore wall surface do not adhere to the inner surface of the skirt portion.
Cylinder block manufacturing method.

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