JP5878342B2 - Cast product having a plurality of protrusions - Google Patents

Description

  The present invention relates to a cast product having a plurality of protrusions.

  Conventionally, for example, in a cylinder head of an engine, when casting a molten metal of a light metal such as an aluminum alloy into a mold, a plurality of walls and protrusions are provided for assembling each component constituting a valve mechanism and the like. Yes. In addition, in a cylinder head of an engine provided with multi-valves (three or more valves per cylinder), casting is performed in a form having a substantially oval boss portion in plan view corresponding to adjacent valves, and after casting, There is one in which a pair of valve guide holes and a spring seat are formed by cutting at both longitudinal ends of an oval boss (see, for example, Patent Document 1). In this structure, a rib portion is formed by a boss portion that remains without being cut between the pair of spring seat portions, and a heat treatment is performed thereafter, whereby a residual generated between the pair of spring seat portions during the heat treatment after casting. The stress can be reduced.

Japanese Patent No. 2583004

  By the way, there is an engine in which a rocker arm is cam-driven by a camshaft and a valve is driven by a rocking motion of the rocker arm. Some of these engines are provided with a hydraulic tappet for automatically adjusting the tappet, or provided with a lost motion mechanism for ensuring followability of the rocker arm with respect to the cam profile of the camshaft.

  In an engine provided with a hydraulic tappet and a lost motion mechanism, for example, a protrusion is provided at the bottom of the cylinder head, and the protrusion is formed into a bottomed cylindrical shape, and the hydraulic tappet and the lost motion mechanism are included therein. There is something that accepts and holds.

  However, for example, in the case of being mounted with an inclination even in the case of a V-type engine or an in-line multi-cylinder engine, the cylinder head is inclined with respect to the horizontal plane. In that case, the lubricating oil in the cylinder head flows downward, but if the protrusion is provided in such a way as to block the flow of the lubricating oil, the recovery efficiency of the lubricating oil deteriorates.

  In addition, when a pair of adjacent and adjacent protrusions are provided corresponding to the multi-valve, if there is a narrow gap between both protrusions, there is a possibility that a shrinkage nest will occur in that part. In order to prevent the occurrence of a sink nest, it is conceivable to form a shape between the two protrusions. However, there is a problem that an oil reservoir is generated by the filled portion.

In the present invention, in order to solve such a problem, in a cast product having adjacent protrusions, it is possible to prevent the occurrence of sinkholes and to prevent oil accumulation from occurring upstream of the protrusions. Has at least two protrusions (61) arranged in parallel with each other along a step formed by the upper surface (62) and the lower surface (63), and from the upper surface so as to fill the bottom of the gap. A lower recessed portion (64) provided at the time of casting, the upper portion of the lower recessed portion is removed after casting, and the recessed portion has a depth reaching the upper surface through the gap above the lower accumulated portion (66) is formed, and the bottom surface of the recess is inclined from the upper surface to the lower surface side .

  According to this, in a cast product including two protrusions arranged with a gap between each other, by providing the lower build-up part so as to fill the bottom part of the gap, there is a sinkhole at the bottom part of the gap between the two protrusions. It can be prevented from occurring. On the other hand, when a projection is provided at the step formed by the upper surface and the lower surface, and a cast product is used in a situation where the liquid flows from the upper surface side to the lower surface side, the liquid is absorbed at both the projecting portion and the lower build-up portion. It will be dammed up. The lower build-up part is effective in preventing the formation of sinkholes, but after casting, part of it can be removed as waste, and after casting, the upper part of the lower build-up part is removed and passed through the gap to the upper surface. Since the recess having the depth to reach is formed, the liquid can flow through the recess.

  In particular, the cast product may be a cylinder head (12) of the engine (10). For example, in a cylinder head that is cast by pouring molten metal of a light alloy into a mold, lubricating oil for lubricating a valve operating mechanism disposed in the cylinder head is supplied into the cylinder head. When the lubricating oil flows down the surface of the bottom of the cylinder head and is collected in the oil pan, there is a problem that the efficiency of collecting the lubricating oil deteriorates if an oil pool is generated on the surface of the bottom of the cylinder head. In the part provided with the two protrusions and the lower build-up part that block the flow of the lubricating oil, a recess is formed in the upper part of the lower build-up part corresponding to the gap between the two protrusions. Lubricating oil can be poured.

  The two protrusions may be processed into a bottomed cylindrical shape after the casting in order to hold the hydraulic tappet or the lost motion mechanism (39). Cylindrical parts can be received by providing a bottomed cylindrical hole in the protrusion, which is suitable for holding a hydraulic tappet or a lost motion mechanism disposed in the cylinder head of the engine. For example, in the case of a multi-valve, when the adjacent valve is narrow and a holding part with two protrusions is provided correspondingly, the gap between the two protrusions is narrow, and both protrusions and the lower build-up part are On the other hand, there is a possibility that an oil reservoir will be generated on the high side in the engine mounted state, but it can be caused to flow out by the recess, and the oil reservoir can be prevented from being generated.

  As described above, according to the present invention, when casting a member including two protrusions arranged close to each other, the protrusion base end side portion of the gap is provided by filling the lower build-up part. By doing this, it is possible to prevent the formation of sink marks in the portion that becomes the bottom surface of the gap between the two protrusions. On the other hand, when a casting is used in a situation where one side sandwiching the two protrusions with respect to the gap is higher than the other side and the liquid flows from the higher one side to the other side, both protrusions And the liquid is dammed up by the lower build-up part. The lower build-up part is effective in preventing the formation of sink marks, but after casting, a part of it can be removed as waste and the upper part of the lower build-up part is removed after casting to form a recess. Can flow through the recess.

It is a front view which shows the principal part of an engine. It is a principal part enlarged view which mainly shows the intake side valve operating mechanism shown by the arrow II line of FIG. (A) is a principal part expansion perspective view which shows the shape by casting of the boss | hub part to which this invention was applied, (b) is principal part sectional drawing seen along the arrow IIIb-IIIb line | wire of (a). . (A) is a principal part expansion perspective view which shows the processed shape of the lower build-up part between boss | hub parts, (b) is principal part sectional drawing seen along the arrow IVb-IVb line | wire of (a). is there.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. A first embodiment in which the present invention is applied to a V-type six-cylinder engine 10 for an automobile will be described in detail. FIG. 1 is a front view showing a main part of an engine 10 according to the embodiment. The engine 10 is placed horizontally in the engine room so that the left side of the plane of FIG. 1 is the front of the vehicle. Hereinafter, the vehicle traveling direction will be described as forward, the vehicle width direction as right or left, and the vertical direction as upward or downward.

  As shown in FIG. 1, the engine 10 includes a cylinder block 11 formed in a V shape by a front cylinder bank 11a inclined to the front side and a rear cylinder bank 11b inclined to the rear side, and upper portions of the cylinder banks 11a and 11b. And a head cover 13 provided on top of each cylinder head 12 as outer shells. The intake device 40 of the engine 10 is disposed inside the cylinder banks 11a and 11b, and the exhaust system 70 is disposed outside.

  In each cylinder bank 11a, 11b, three cylinder bores 14 are provided side by side in the front and back direction in the figure, and a combustion chamber 21 is formed in a portion corresponding to each cylinder bore 14 of each cylinder head 12. The cylinder bore 14 and the combustion chamber 21 constitute a cylinder. A piston 15 connected to the crankshaft 17 via a connecting rod 16 is slidably disposed in each cylinder bore 14.

  The combustion chamber 21 communicates with one end of each of an intake port 22 that opens to the side of the cylinder head 12 inside the cylinder bank and an exhaust port 23 that opens to the side of the cylinder head 12 outside the cylinder bank. . Two intake ports 22 and two exhaust ports 23 are provided for each combustion chamber 21. An intake valve 24 and an exhaust valve 25 are interposed at the boundary between the combustion chamber 21 and the intake port 22 and the exhaust port 23. The intake valve 24 and the exhaust valve 25 are opened and closed by a valve mechanism 30.

  The valve operating mechanism 30 swings the cam shaft 32 in which the cams 31 are arranged, the intake rocker arm 33 and the exhaust rocker arm 34 interposed between the cam 31 and the intake valve 24 and the exhaust valve 25, and the intake rocker arm 33. An intake rocker shaft 35 that is movably supported and an exhaust rocker shaft 36 that movably supports an exhaust rocker arm 34 are provided. The camshaft 32 rotates in synchronization with the rotation of the crankshaft 17, and the intake valve 24 and the exhaust valve 25 are driven by the cam 31 via the intake rocker arm 33 and the exhaust rocker arm 34.

  FIG. 2 is an enlarged view of a main part mainly showing the intake side valve operating mechanism indicated by the arrow II line in FIG. 1 of the cylinder bank 11a. The cylinder bank 11b may have the same structure, and the cylinder bank 11a will be described below as a representative.

  The cylinder head 12 has a substantially rectangular parallelepiped lower portion (cylinder block 11 side portion) that is long in the axial direction of the crankshaft 17 and a box-shaped upper portion that is provided at the upper end of the lower portion and has an open upper surface in the drawing. doing. In the upper part of the cylinder head 12, there is formed a substantially rectangular box-shaped valve operating chamber 37 that opens upward by front, rear, left and right walls that are erected upward along the four sides of the lower part of the cylinder head 1. . The valve mechanism 30 is received in the valve chamber 37.

  The engine according to the present embodiment includes, as a variable cylinder system, an intake rocker arm 33 corresponding to a cylinder to be stopped, which includes a drive rocker arm 33a that acts on the intake valve 24, and a free rocker arm 33b that is adjacent to the drive rocker arm 33a. . One end of the free rocker arm 33b is driven by the cam 31 to swing, and both the rocker arms 33a and 33b are selectively connected via a connecting pin 38.

  When the cylinder is stopped, the connecting pin 38 between the two rocker arms 33a and 33b is buried in either one to release the connection between the two rocker arms 33b, but the free rocker arm 33b is cam-driven. In order to suppress fluttering of the free rocker arm 33b, a lost motion spring 39 constituting a lost motion mechanism that biases one end of the free rocker arm 33b in a direction to press against the cam 31 is provided. The lost motion spring 39 is supported by a cylindrical boss portion 61 erected on the bottom surface of the box-shaped upper portion of the cylinder head 12 so as to face the free rocker arm 33b.

  Lubricating oil is supplied into the cylinder head 12 in order to lubricate the valve mechanism 30, and the lubricating oil flows to the lower side in the cylinder head 12 and returns to the return oil path (in the cylinder block 11 ( It is collected in an oil pan (not shown) via a not shown.

  When the cylinder head 12 is inclined to one side in the mounted state as in the V-type engine 10 of the present embodiment, as shown in FIG. 2 on the bottom surface 12a around the boss portion 61 of the cylinder head 12, There is a case where a step is formed between the upper surface 62 and the lower surface 63, and the boss portion 61 is provided at the step portion. As described above, the boss portion 61 is erected from the bottom surface of the cylinder head 12, and when the free rocker arm 33b is provided adjacent to the boss portion 61, the two boss portions 61 are arranged side by side with a gap.

  Next, the manufacturing procedure when forming the two boss portions 61 will be described with reference to FIGS. FIG. 3 is an enlarged view of the boss portion 61 in a cast product in a state where the cylinder head 12 is cast with a molten metal such as an aluminum alloy using a mold. As shown in FIG. 3A, both boss portions 61 as two projecting portions are juxtaposed so as to project in the same direction with a gap d. The upper surface 62 and the lower surface 63 are directions intersecting (orthogonal) with the arrangement direction (alignment direction) of the boss portions 61, and are provided with the boss portions 61 sandwiched in the direction passing through the gap d. It is in a position lower than the part 61. In such a cast product having both protrusions arranged side by side with a gap d, a sink nest is likely to be generated at the bottom of the gap between the both protrusions by casting, so that the bottom of the gap d is filled to prevent the occurrence of the sink nest. Further, a lower build-up portion 64 is formed by casting.

  Although the generation of the sink nest is suppressed in this way, in order to reliably suppress the generation of the sink nest, the height of the lower built-up portion 64 is set to the upper surface 62 as shown in FIG. May be higher. The upper surface 62 is on the upstream side in the flow of the lubricating oil, and as it is, an oil reservoir in which the lubricating oil is blocked by the lower build-up portion 64 is generated on the upper surface 62 side, and the lubricating oil is shown by a two-dot chain line in FIG. It accumulates as shown in OL.

  On the other hand, as shown in FIG. 3A, the upper part of the lower build-up part 64 is removed after casting by, for example, a mill 65 to form a groove-like recess 66 on the upper part of the lower build-up part 64. FIG. 4 is a view corresponding to FIG. 3 in which a recess 66 is formed in the upper portion of the lower build-up portion 64. The recess 66 may be formed to a depth such that the bottom surface 66a thereof is at the same height as the top surface 62 as shown in FIG. 4B.

  The concave portion 66 extends in the direction passing through the gap d, and the bottom surface 66a is formed as the same surface as the upper surface 62 or as a smoothly continuous surface and is inclined toward the lower surface 63, thereby flowing into the high portion 62. The oil is discharged to the bottom surface 63 side through the recess 66. As a result, an oil reservoir is prevented from occurring on the upper surface 62 side.

  After or before processing of the recess 66, the boss portion 61 is formed with a bottomed cylindrical spring holding hole 61a for receiving the lost motion spring 39 by, for example, a drill. The lower half portion of the lost motion spring 39 is coaxially received in the spring holding hole 61a, the upper half portion of the lost motion spring 39 protrudes from the boss portion 61, and the protruding end engages with the free rocker arm 33b. To do.

  The cross-sectional shape of the recess 66 may be a U-shaped groove having the same width as the width of the gap d. However, when the thickness is sufficiently ensured in relation to the spring holding hole 61a, the gap d The undercut shape may be wider than the width. By making the undercut shape, the reduction of the residual stress after the heat treatment can be promoted.

  Further, the bottom surface 66a of the recess 66 reaching the top surface 62 does not have to be the same height as the top surface of the high portion 62. The bottom surface 66a is lower than the top surface 62, and a part of the top surface 62 is formed by the bottom surface 66a of the recess 66. A lower portion may be formed. Further, the bottom surface 66a of the recess 66 may be inclined downward toward the lower portion 63 in the mounted state of the engine 10, and the bottom surface 66a of the recess 66 is inclined downward from the upper surface 62 toward the lower surface 63, for example. There is no need to slope.

  Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to such embodiments so that those skilled in the art can easily understand, and departs from the spirit of the present invention. It is possible to change appropriately within the range not to be.

  In particular, in the above embodiment, the boss portion 61 in the holding structure of the lost motion mechanism provided in the cylinder head of the engine has been described. However, the holding portion of the hydraulic tappet for automating tappet adjustment also has a protruding shape. In some cases, this structure is also applicable. In addition, the cast product having at least two adjacent protrusions protruding from the bottom surface thereof can be applied to any cast product in the case where a built-up portion is provided in order to prevent the occurrence of sink marks.

  In addition, all the components shown in the above embodiment are not necessarily essential, and can be appropriately selected without departing from the gist of the present invention.

10 Engine 12 Cylinder head 39 Lost motion spring (lost motion mechanism)
61 Boss (projection)
62 Upper surface 63 Lower surface 64 Lower build-up portion 66 Recess 66a Bottom surface d Clearance

Claims (1)

A cylinder head manufacturing method in which at least two bottomed cylindrical bosses holding a hydraulic tappet or a lost motion mechanism are arranged in parallel with each other along a step formed by an upper surface and a lower surface,
It said at least two projections are arranged with a gap from each other along the step, and casting the cylinder head as the lower padding portion is provided higher than the upper surface so as to fill the bottom of the gap,
After casting of the cylinder head, and removing the lower padding portion, a recess passing through the pre-Symbol gap depth from said upper surface leading to said top surface and a bottom surface which is inclined to said lower surface,
A method of manufacturing a cylinder head having a plurality of protrusions , wherein the two protrusions are processed into the bottomed cylindrical boss after the cylinder head is cast.

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