JP2021055622A - cylinder head - Google Patents

Abstract

To provide a cylinder head which is excellent in stiffness and cooling performance in a form capable of manufacturing the cylinder head at high dimension accuracy and at a favorable yield.SOLUTION: Upper and lower jackets are formed at a cylinder head 2, and a V-shaped rectification rib 26 contributing to the control of a flow of cooling water is arranged in a point of an inter-bore part 6 of a lower-stage jacket 7. Cooling performance and stiffness can be improved by the rectification rib 26. Also, communication holes 27, 28 located at a sideway of the rectification rib 26 are formed at slabs 9, 10 for forming the jackets 7, 8, and a boss part 29a of a plug 29 arranged at the upper communication hole 28 is arranged so as to be surrounded by the rectification rib 26. The communication holes 27, 28 are formed resulting from the stable support of a core at casting, and can control water passage from the lower-stage jacket 7 to the upper-stage jacket 8 by using the plug for blocking the communication holes.SELECTED DRAWING: Figure 2

Description

The present invention relates to a cast cylinder head having two upper and lower jackets.

It has been conventionally known that in an internal combustion engine provided in a vehicle such as an automobile, a jacket having two upper and lower stages is formed on a cylinder head. When a two-stage jacket is formed on the cylinder head in this way, in the casting mold, the part that becomes the jacket is formed of sand core, and the part corresponding to the intermediate slab between the upper and lower jackets and the upper jacket. The portion corresponding to the upper slab located above is a space through which the metal hot water flows, but there is a problem that the core floats and is deformed or damaged by the pressure of the metal hot water flowing into the space during casting.

Therefore, in Patent Document 1, the upper and lower cores are connected by a boss to prevent the core from being deformed or damaged, and the upper and lower communication holes formed in the slab by providing the boss are plugged into one plug. It is disclosed that it will be closed with. Specifically, in Patent Document 1, the small diameter portion of the boss is inserted into the communication hole of the intermediate slab, but in order to absorb the dimensional error, a gap of 0.1 to 3 mm is provided around the small diameter portion. ..

Japanese Unexamined Patent Publication No. 2010-216338

By the way, the reason why the upper and lower two-stage jackets are formed on the cylinder head is to intensively cool the part near the exhaust port to cool it efficiently, so that a large amount of cooling water flows to the lower jacket. It is common to design. In this case, it is preferable to have a rib (rectifying rib) for controlling the flow of cooling water in the lower jacket, but it is difficult to find such consideration from Patent Document 1.

Further, if the lower jacket is provided with continuous rectifying ribs on the upper surface and the lower surface, the lower slab that defines the lower surface of the lower jacket and the intermediate slab that defines the upper surface of the lower jacket are connected by the rectifying ribs. Although there is an advantage that the rigidity of the cylinder head can be improved, in casting using a mold, the strength of the core may decrease because the portion of the rectifying rib becomes a space.

Further, when two upper and lower jackets are formed, it is rational to flow a large amount of cooling water through the lower jacket, but from the viewpoint of cooling uniformity and the like, water flows from the lower jacket to the upper jacket. It is preferable that it can be secured to some extent. However, in Patent Document 1, since the communication hole of the intermediate slab is almost closed by the plug, it can be said that fine cooling cannot be expected.

The present invention aims to improve such a situation.

The present invention relates to a cast cylinder head, which is a cylinder head.
"A two-stage water jacket consisting of an upper jacket and a lower jacket arranged so as to overlap in a plan view is formed, and a rectifier that controls the flow of cooling water is formed in a substantially upper portion of the lower jacket between the bores. Ribs are formed
Further, a communication hole located in the vicinity of the rectifying rib is concentrically formed in the intermediate slab between the upper and lower jackets and the upper slab that defines the upper surface of the upper jacket, and is provided on the upper slab. The communication hole is closed by a plug inserted from above into the upper communication hole, while a boss portion provided in the plug is inserted into the lower communication hole made in the lower slab, and the boss It forms a gap between the part and the lower communication hole through which cooling water can pass. "
It is configured as.

The invention of the present application can be developed in various ways, and as an example, in claim 2,
"The gap between the boss portion of the plug and the lower communication hole is formed in an L shape having at least a part thereof and a gap along the outer circumference of the boss portion and a gap along the end face."
The configuration is adopted.

In the present invention, since the flow of the cooling water in the lower jacket can be controlled by the rectifying rib, the cooling performance of the cylinder head can be improved. Further, since the intermediate slabs and the lower slabs located above and below the lower jacket are connected by the rectifying ribs, the rigidity of the cylinder head can be improved. That is, the rigidity of the cylinder head can be improved by effectively utilizing the rectifying rib.

On the other hand, when the rectifying rib connecting the intermediate slab and the lower slab is formed, in the manufacturing mold, the portion where the rectifying rib is molded becomes a space, which causes a decrease in the strength of the core. However, in the present invention, a communication hole is formed in the vicinity of the rectifying rib, but since the communication hole is a boss connecting the cores in the mold, deformation or damage of the core can be prevented. That is, the decrease in the strength of the core caused by the formation of the rectifying rib can be prevented by forming the communication hole.

Therefore, in the present invention, the cylinder head can be provided in a state of excellent dimensional accuracy and productivity (yield) while being a cylinder head having excellent cooling performance and rigidity.

Further, in the present invention, the cooling water of the lower jacket can be passed through the lower communication hole to the upper jacket, but the amount of water flowing from the lower jacket to the upper jacket can be finely set by adjusting the gap between the gaps. Therefore, the flow rate of the upper jacket and the volume flow of the lower jacket can be set to appropriate amounts to improve the cooling performance of the cylinder head.
In this case, the gap between the boss portion and the lower communication hole can be formed simply straight, but in this case, the flow rate may change significantly due to a slight difference in the gap spacing, and fine adjustment can be made. It can be difficult.

On the other hand, if the gap is formed in an L shape as in claim 2, it becomes difficult to flow from the lower jacket to the upper jacket due to an increase in flow resistance. Therefore, the change in flow rate should be moderated while increasing the size of the gap. Can be done. Therefore, the flow rate can be easily finely adjusted.

It is a vertical cross-sectional view which cut at the part between the bores when the cylinder head is seen from the direction of the crank axis, and is the I-I visual cross-sectional view of FIG. It is a figure which shows the lower jacket, and is the II-II sectional view of FIG. It is a figure which shows the upper jacket, and is the III-III sectional view of FIG. FIG. 5 is a cross-sectional view of the mold corresponding to FIG.

(1). Basic structure Next, an embodiment of the present invention will be described with reference to the drawings. In the following, the front-back and left-right wordings are used to specify the direction, but the front-back direction is the crank axis direction, with the side where the timing chain is arranged as the front and the side where the mission case is arranged as the back. The left-right direction is a direction orthogonal to the crank axis and the silin tabore axis. The front-back directions are clearly shown in FIGS.

As shown in FIGS. 2 and 3, the present invention is applied to a 3-cylinder engine having three cylinder bores 1, and as shown in FIG. 1, the cylinder head 2 is fixed to the cylinder block 3 with a head bolt 5 via a gasket 4. Cylinder. The cylinder head 2 is a cast product made of aluminum.

Since the engine has three cylinders, the cylinder block 3 has two bores 6. FIG. 1 is a cross-sectional view taken along a plane that is orthogonal to the crankshaft and passes through the inter-bore portion 6, and as shown in FIG. 1, a lower jacket in which a corresponding portion overlaps in a plan view inside the cylinder head 2. 7 and the upper jacket 8 are formed.

Therefore, the cylinder head 2 includes a lower slab (lower deck portion) 9 that defines the lower surface of the lower jacket 7, an intermediate slab 10 that divides the upper and lower jackets 8 and 7, and an upper slab (upper) that defines the upper surface of the upper jacket 8. It is equipped with a deck unit) 11.

In addition, FIG. 1 will be described. Reference numeral 12 indicates a rocker arm, reference numeral 13 indicates a spring supporting the rocker arm, reference numeral 14 indicates a lash adjuster mounting portion, and reference numeral 15 indicates an oil passage for the lash adjuster. Indicated, reference numeral 16 indicates a fuel injection injector, reference numeral 17 indicates a camshaft, and reference numeral 18 indicates an exhaust collecting passage. Therefore, in FIG. 1, the intake side surface 2a is located on the left side of the paper surface, and the exhaust side surface 2b is located on the right side of the paper surface.

Explaining FIGS. 2 and 3, reference numeral 20 is a plug hole (ignition hole), reference numeral 21 is a valve insertion hole, and reference numeral 22 is a head bolt insertion hole. Is formed in.

As shown in FIGS. 2 and 3, the cooling water flows through the jackets 7 and 8 from the front to the back. Therefore, a group of cooling water inlets 23 from below is provided at a portion of the cylinder head 2 closer to the intake side, and the cooling water inlets 23 and the front end portion of the lower jacket 7 are communicated with each other by a passage. (Note that each cooling water inlet 23 communicates with a water supply port formed in the cylinder block 3 (or gasket 4)).

On the other hand, a cooling water outlet 24 communicating with the lower jacket 7 and the upper jacket 8 is formed at the rear portion of the cylinder head 2, and the cooling water outlet 24 is a distribution unit provided with a branch passage to a radiator, a heater core, or the like (FIG. Not shown) is connected. Further, in the front portion of the cylinder head 2, a distribution passage for flowing cooling water from the cooling water inlet 23 to the upper jacket 8 can be formed.

(2). Rectifying ribs and communication holes / mold As shown in FIG. 2, a plan view V extending from the intake side to the exhaust side at a portion of the lower jacket 7 located above the two bores 6 A shaped rectifying rib 26 is formed.
Then, in the lower jacket 7, for example, the cooling water rising from the water jacket formed in the cylinder block 3 through the communication hole 4a (see FIG. 1) of the gasket 4 is directed by the rectifying rib 26 toward the exhaust side. Is evenly divided. Therefore, the cold water can be evenly diffused into the lower jacket 7.

Further, the intermediate slab 10 and the upper slab 11 are provided with communication holes 27 and 28 located slightly on the exhaust side from the rectifying rib 26, and the upper communication holes 28 formed in the upper slab 11 are provided with the upper communication holes. A plug 29 that closes 28 is attached by screwing or press-fitting from above. The plug 29 is formed with a boss portion 29a that enters the lower communication hole 27 formed in the intermediate slab 10.

A gap 30 is formed between the boss portion 29a of the plug 29 and the lower communication hole 27 so that the cooling water can pass from the bottom to the top. Therefore, the amount of water flowing from the lower jacket 7 to the upper jacket 8 can be adjusted by selecting the dimension of the gap 30, but the gap 30 can be adjusted by changing the outer diameter dimension of the boss portion 29a, so that the adjustment is easy. Is.

The boss portion 29a is located behind in the flow direction of the cooling water toward the rectifying rib 26. Therefore, the cooling water does not directly hit the boss portion 29a, and the boss portion 29a does not impair the rectifying function. In addition, the cooling water does not excessively pass through the gap 30. This is a great advantage that the rectifying rib 26 is formed in a V shape so that the rectifying rib 26 surrounds the boss portion 29a.

Further, as shown in FIG. 1, by overlapping a part of the lower communication hole 27 with the rectifying rib 26, a certain range of the gap 30 closer to the rectifying rib 26 is positioned on the lower end surface of the boss portion 29a. It is formed in an L shape having a portion formed and a portion located on the outer peripheral surface.

When a part of the gap 30 is formed in an L shape in this way, the pressure loss becomes high when the cooling water flows in and it becomes difficult for the gap 30 to flow in. it can. Therefore, fine adjustment (tuning) of the flow rate can be easily and accurately performed.

The cooling water tries to flow in a straight line, but in the embodiment, the lower communication hole 27 is in the shadow of the rectifying rib 26, so that the cooling water tends to pass through the lower communication hole 27. Since it is originally difficult to flow into the gap 30, even if the size setting of the gap 30 is rough, the flow rate can be easily finely adjusted.

As can be seen from the comparison of FIGS. 2 and 3, the lower jacket 7 has more meat than the upper jacket 8. This is due to the fact that the structure of the lower jacket 7 tends to be complicated due to the ports, injectors, etc., and that it is necessary to support the large explosive force applied to the lower slab 9.

As described above, the upper jacket 8 has a small meat portion, and the circumference of the boss portion 29a of the plug 29 is a wide space. Therefore, the cooling water that has passed through the gap 30 and has risen up flows toward the rear while diffusing in all directions. In FIG. 3, only the flow of the cooling water rising from the gap 30 is shown, but as described above, the flow from the front portion can also be formed.

FIG. 4 shows a cross section of the mold 32 at the same position as in FIG. The meat part of the product becomes a sand mold such as a core in the mold 32, and the empty space of the product becomes a space in the mold. Therefore, the mold 32 has an outer frame 33, a first core 34 corresponding to the space above the upper slab 11, a second core 35 corresponding to the upper jacket 8, and a third middle corresponding to the lower jacket 7. It has a child 36. The third core 36 has a large number of feet 37 for stabilization. The foot portion 37 has a downward opening hole 38 (see FIG. 1) in the cylinder head 2, but a hole that does not require a water flow function is closed by a gasket 4.

Then, in order to form the upper communication hole 28 of the cylinder head 2, the first boss 39 is arranged between the first core 34 and the second core 35 to form the lower communication hole 27 of the cylinder head 2. Therefore, the second boss 40 is arranged between the second core 35 and the third core 36. The first boss 39 is formed on either the first core 34 or the second core 35, and the second boss 40 is formed on either the second core 35 or the third core 46. ing.

In this way, since the three-stage cores 34, 35, 36 are integrally supported via the bosses 39, 40, the metal hot water flowing into the space 41 causes the second core 35 and the third core 36 to be integrally supported. It will not be deformed (floated) or damaged. Therefore, the cylinder head 2 can be cast with high accuracy. Therefore, the cylinder head 2 having excellent distribution of cooling water and high rigidity can be manufactured with high dimensional accuracy and high yield.

The lower communication hole 27 can be machined by an end mill so as to partially overlap with the rectifying rib 26. Therefore, by selecting the outer diameter and cutting depth of the end mill, the dimensions of the gap 30 can be arbitrarily set, and the amount of cooling water flowing through the gap 30 can be finely adjusted.

Although the embodiments of the present invention have been described above, the present invention can be embodied in various ways. For example, the form of the rectifying rib 26 can be appropriately changed depending on the flow mode of the cooling water and the like. For example, in a plan view, it can be formed into a C shape or a U shape instead of the V shape. Alternatively, it can be formed in the shape of a triangular rod. Further, the rectifying ribs 26 and the communication holes 27 and 28 may be arranged substantially above the bore-to-bore portion 6, and may be slightly deviated from the bore-to-bore portion 6 in a strict sense in the front-rear direction and the left-right direction.

The invention of the present application can be embodied in the cylinder head 2. Therefore, it can be used industrially.

1 Cylinder bore 2 Cylinder head 6 Between bores 7 Lower jacket 8 Upper jacket 9 Lower slab 10 Intermediate slab 11 Upper slab 23 Cooling water inlet 24 Cooling water outlet 26 Rectifying rib 27 Lower communication hole 28 Upper communication hole 29 Plug 29a Boss part 30 Water gap 32 Mold 33 Outer frame 34 1st core 35 2nd core 36 3rd core 39,40 Boss 41 Space corresponding to the meat part of the cylinder head

Claims (2)

A cast cylinder head fixed to the top surface of a cylinder block in which a plurality of cylinder bores are formed.
A two-stage water jacket consisting of an upper jacket and a lower jacket arranged so as to overlap in a plan view is formed, and a rectifying rib that controls the flow of cooling water is formed in a substantially upper portion between the bores of the lower jacket. Is formed,
Further, a communication hole located in the vicinity of the rectifying rib is concentrically formed in the intermediate slab between the upper and lower jackets and the upper slab that defines the upper surface of the upper jacket, and is provided on the upper slab. The communication hole is closed by a plug inserted from above into the upper communication hole, while a boss portion provided in the plug is inserted into the lower communication hole made in the lower slab, and the boss A gap is formed between the part and the lower communication hole through which cooling water can pass.
cylinder head. The gap between the boss portion of the plug and the lower communication hole is formed in an L shape having at least a part thereof having a gap along the outer circumference of the boss portion and a gap along the end face.
The cylinder head according to claim 1.

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