JP2021055584A - Main body block of multicylinder internal combustion engine - Google Patents

Abstract

To maintain the roundness of a bore in a high state while securing the easiness of processing, in a mono-block in which a cylinder head part and a cylinder block part are integrated with each other.SOLUTION: A cylinder head part 2 and a cylinder block part 1 are integrally cast. A crankshaft 5 is held to a crank case part 3 which is different from the cylinder block part 1, and the crank case part 3 and the cylinder block part 1 are fixed to each other with bolts 18. A lower-part horizontal rib 20 which is long in a crankshaft axial line direction is formed at a lower part out of a longitudinal side face of the cylinder block part 1. Each cylinder 6, the lower-part horizontal rib 20 and a lower deck part 15 are mutually reinforced by one another, and even if tension generated by the bolts 18 acts on the cylinder 6, the deformation of the cylinder 6 can be remarkably suppressed. By this constitution, a bore can be maintained in a high-roundness state.SELECTED DRAWING: Figure 2

Description

The present invention relates to a monoblock type main body block in which a cylinder block portion and a cylinder head portion are integrally cast in a multi-cylinder internal combustion engine.

The internal combustion engine includes a cylinder block portion and a cylinder head portion as a main body block, and generally, these cylinder block portions and the cylinder head portion are manufactured separately and are fastened with a head bolt via a gasket. There is. On the other hand, as disclosed in Patent Document 1, for example, it has been proposed to integrally cast the cylinder block portion and the cylinder head portion to form a monoblock.

In Patent Document 1, the cylinders are alternately tilted to one side and the other side when viewed from the crankshaft direction to secure the bearing area of the crankshaft, make it compact, and the length of the cylinder block portion. Rigidity is improved by providing reinforcing ribs on the side surfaces that connect adjacent cylinders.

Japanese Unexamined Patent Publication No. 11-107449

In Patent Document 1, the cylinder block portion is integrally formed with a crankcase portion in which the crankshaft line is rotatably held. However, if the crankcase portion is integrated with the cylinder block portion, there are problems that the mold becomes complicated and the yield is deteriorated at the time of casting, and that it takes time and effort to process the inner surface of the cylinder and the like.

Regarding this point, it can be said that the crankcase portion may be a separate member and the crankcase portion and the cylinder block portion may be fixed with bolts. However, when the crankcase portion is configured as a separate member in this way, the pulling force of the bolt is applied to the cylinder. There is a concern that the roundness of the lower part of the cylinder will decrease, the smooth movement of the piston will be impaired, the mechanical loss will increase, and the amount of blow-by gas blown through will also increase.

The present invention aims to improve such a situation.

The main body block of the present invention is
"It has a cylinder block portion formed by arranging a plurality of cylinders in the direction of the crank axis, and a cylinder head portion formed by an intake port and an exhaust port corresponding to each cylinder, and these cylinder block portions and the cylinder head portion. Is continuous as one cast product. "
It is a basic configuration.

And in the above basic configuration
"The lower end of the cylinder block portion is located above the crankshaft, and a crankcase that rotatably holds the crankshaft is fixed to the lower surface of the cylinder block portion.
Further, in the longitudinal outer surface of the cylinder block portion, near or lower than the height position of the top surface of the piston at the bottom dead center, in a state of being integrally connected to the outer surface of each cylinder, in the crank axis direction. A horizontally long rib is formed. "
It retains the feature.

The invention of the present application can be developed in various ways. As an example, in claim 2,
"A boss portion for fixing the crankcase with a bolt is formed at the lower portion of the longitudinal side surface (side surface on the intake side and the side surface on the exhaust side) of the cylinder block portion, and the upper end of the boss is formed from the horizontally long rib. Is also in a low position. "
The configuration is adopted.

By the way, the crankcase is rotatably supported by the crank journal and the crank cap, but in order to make the engine compact, it is preferable that the distance between the bores is as small as possible, while the crank journal has a certain width (crankshaft line). The thickness in the direction) is required, so the thickness of the crank journal is made larger than the thickness of the space between the bores.

In the method in which the cylinder block and the cylinder head are separated, the cylinder bore can be processed from the top surface direction, so that there is no problem even if the crank journal is thicker than the bore portion, but the cylinder head portion and the cylinder block portion In the monoblock structure in which is integrated, the cylinder bore must be processed from below. Therefore, if the crank journal is integrated in the cylinder block portion, in order to give the crank journal the required width, the space between the bores is required. If the interval must be increased, the main body block will become larger than necessary.

The same applies to the machining of the valve holes (particularly the part where the valve umbrellas overlap) where the intake valve and exhaust valve are located. If the crank journal is integrated, apply a cutting tool (drill) to the crank journal. The crank journal must fit between the bores in order to machine the valve hole without the need for it, and as mentioned above, the distance between the bores must be increased in order for the crank journal to have the required width. If you do not get it, the main body block will become larger than necessary.

On the other hand, in the present invention, since the crankcase portion that holds the crankshaft is a separate member from the cylinder block portion, the cylinder bore and the valve hole can be machined without increasing the distance between the bores. it can.

When the crankcase portion is fastened to the lower surface of the cylinder block portion with bolts, stress is generated in each cylinder due to the pulling of the bolts, and therefore, the lower portion of the cylinders is particularly deformed and the roundness tends to decrease. Regarding this point, it can be said that a thick deck portion should be formed at the lower end of the cylinder block portion so that the pulling force of the bolt does not act on the cylinder, but this increases the weight of the cylinder block portion and improves fuel efficiency. It makes it worse.

On the other hand, in the present invention, since each cylinder is connected by a horizontally long rib at the lower part thereof, even if the pulling force of the bolt acts on each cylinder, the horizontally long rib and each cylinder reinforce each other and the cylinder is deformed. Can be prevented. Therefore, the lower portion of each cylinder can be maintained at a high roundness without providing a thick deck portion at the lower end of the cylinder block portion. As a result, smooth operation can be realized by maintaining the roundness of the bore while reducing the weight.

When the configuration of claim 2 is adopted, the pulling force of the bolt does not spread to the upper part of the cylinder, so that even if the crankcase portion is deformed for some reason during operation, the deformation does not spread to the upper part of each cylinder. Absent. That is, even if the crankcase portion is deformed, the deformation is absorbed in the lower part of the cylinder. Therefore, it is possible to prevent the cylinder from bending as a whole and maintain reliability.

It is a perspective view which shows the embodiment. FIG. 1 is a schematic cross-sectional view taken along the line II-II of FIG. FIG. 2 is a sectional view taken along line III-III in FIG.

(1). Basic structure Next, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, front / rear / left / right words are used to specify the direction, but the side where the timing chain is arranged is the front and the side where the mission case is arranged is the back. The left-right direction is a direction orthogonal to the crank axis and the cylinder bore axis. The directions are clearly shown in FIGS. 1 and 3.

The internal combustion engine includes, as basic elements, a monoblock type main body block in which the cylinder block portion 1 and the cylinder head portion 2 are integrated, and a crankcase portion 3 fixed to the lower surface of the cylinder block portion 1. As shown in FIG. 2, the crankshaft 5 is rotatably held by the crankcase portion 3 via the crank cap 4.

The cylinder block portion 1 is formed with three cylinders 6 arranged in the direction of the crank axis, while the cylinder head portion 2 has a pent roof-shaped recess 7 forming a combustion chamber concentric with the cylinder 6. It is formed. The main body block is a cast aluminum product, but the inner surface (bore) of each cylinder 6 is composed of an iron liner 6a fixed by casting.

As shown in FIG. 2, in the cylinder head portion 2, a pair of intake ports 8 and exhaust ports 9 facing each recess 7 are formed on both sides of the crank axis, and each exhaust port 9 is formed. It communicates with the meeting space 10. The collecting space 10 includes one exhaust outlet 11 opened on the exhaust side surface 2a of the cylinder head portion 2. The cylinder head portion 2 is formed with spark plug mounting holes (ignition holes) 12 opened in each recess 7.

Further, a water jacket 13 through which cooling water flows is formed mainly in the cylinder head portion 2. The lower end of the water jacket 13 is inserted into the upper end of the cylinder block portion 1. Therefore, compared to the conventional internal combustion engine, the cylinder block portion 1 is hardly cooled. This is because the heat transfer property between the cylinder head portion 2 and the cylinder block portion 1 is good, and the cooling effect of the cylinder head portion 2 directly affects the cylinder block portion 1.

Therefore, the thickness of each cylinder 6 constituting the cylinder block portion 1 is thinner than that of the two-part system in which the cylinder block portion 1 and the cylinder head portion 2 are separated. Therefore, the cylinder block portion 1 is considerably slimmer and lighter than the two-part system.

(2). Horizontal rib A state in which each cylinder 6 is connected to each cylinder 6 on the longitudinal side surface of the upper end portion of the cylinder block portion 1 in order to prevent a decrease in rigidity due to thinning of each cylinder 6 over a substantially overall length (overall height). The upper horizontally long rib 14 extending long in the crank axis direction is formed.

A flange-shaped lower deck portion 15 is formed at the lower end of the cylinder block portion 1, while upper and lower flange-shaped deck portions 16 and 17 are also formed on the crankcase portion 3 under the cylinder block portion 1. The deck portion 15 and the upper deck portion 16 of the crankcase portion 3 are fixed by a group of bolts 18 shown in FIG.

An oil pan (not shown) is fixed to the lower deck portion 17 of the crankcase portion 3. Further, as shown in FIG. 3, recesses 19 for arranging timing chains are formed on the front surface of the cylinder block portion 1 (and the front surface of the cylinder head portion 2 and the front surface of the crankcase portion 3). The timing chain is covered by a front cover (not shown).

A lower horizontally long rib 20 that extends long in the crank axis direction while being connected to each cylinder 6 is integrally formed on the lower portion of the longitudinal side surface of the cylinder block portion 1. The lower horizontally elongated rib 20 corresponds to the horizontally elongated rib described in the claims, and is formed at a position slightly higher than the top surface of the piston 21 at the bottom dead center, as shown in FIG. Further, vertically elongated flanges 22 and 23 projecting in the left-right direction are formed at the front end and the rear end of the cylinder block portion 1, and the upper and lower horizontally long ribs 14 and 20 are connected to the front and rear flanges 22 and 23. ..

The lower horizontally long rib 20 protrudes from each cylinder 6 with equal dimensions in the solid line state, but as shown by the alternate long and short dash line in FIG. 3, it is formed so as to widen rearward so that the protruding dimension increases from the front to the rear. You may. By increasing the protruding dimension toward the rear in this way, the rigidity of the rear end portion of the cylinder block portion 1 can be improved, so that a heavy mission case can be stably supported.

The lower deck portion 15 of the cylinder block portion 1 and the upper and lower deck portions 16 and 17 of the crankcase portion 3 have large rear overhang dimensions. This corresponds to the size of the mission case, but it also has the meaning of improving the reinforcement function. By forming the lower horizontally elongated ribs 20 so as to widen rearward in accordance with the shapes of the deck portions 15, 16 and 17, the rigidity of the rear portion of the cylinder block portion 1 can be greatly improved.

The upper horizontally long rib 14 can also be formed so that the left and right width increases from the front to the back, but since the upper horizontally long rib 14 is located above the mission case, it spreads backward. Even if it is formed, it does not contribute much to improving the mounting strength of the mission case. Therefore, at least the lower horizontally elongated rib 20 may be formed so as to spread backward.

The bolt 18 is arranged at a portion where each cylinder 6 is most widened in the left-right direction, and is screwed into a boss portion 24 formed in the cylinder block portion 1 from below. Therefore, when the bolt 18 is tightened, a tensile force acts on each cylinder 6 to generate stress in the cylinder 6. If the lower horizontally long rib 20 is not present, the pulling force may spread to the lower part of the cylinder 6 and the cylinder 6 may be deformed distortedly.

On the other hand, when the lower horizontally long rib 20 is formed at a height position near the top surface of the piston 21 at the top dead center as in the embodiment, the tensile force is prevented from acting upward and the cylinder is cylinder. The rigidity of the lower part of 6 is improved. Therefore, the bore of each cylinder 6 is maintained at a high roundness over the entire vertical length.

That is, since the lower horizontally elongated rib 20, each cylinder 6, and the lower deck portion 15 form a U-shaped frame having an outwardly open cross section, the lower horizontally elongated rib 20, each cylinder 6, and the lower deck portion 15 Reinforce each other to increase the section modulus, and as a result, even if the tensile force of the bolt 18 acts on the cylinder 6, the deformation of the cylinder 6 is prevented. Then, as the height of the lower horizontally elongated rib 20 increases, the reinforcing effect of the frame body decreases, but as in the present embodiment, the lower horizontally elongated rib 20 is provided near the height of the top surface of the piston 21 at the bottom dead center. When arranged, since the distance between the lower horizontally elongated rib 20 and the lower deck portion 15 is small, it is possible to prevent the cylinder 6 from being deformed even if a bending force acts on the cylinder 6.

Further, the lower deck portion 15 is pulled as shown by the arrow A in FIG. 2 by tightening the bolt 18, and then the cylinder 6 is pulled in the direction indicated by the arrow B. Therefore, if no measures are taken, the lower portion of the cylinder 6 is deformed into an elliptical shape and the roundness of the bore deteriorates. For this reason, the lower lateral rib 20 prevents the cylinder 6 from bending in the direction of the arrow B. As a result, the overall roundness of the bore can be maintained.

As already mentioned, as shown in FIG. 2, the bolt 18 for fastening the crankcase portion 3 and the cylinder block portion 1 is inserted into the upper deck portion 16 of the crankcase portion 3 from below, and as shown in FIG. 1, the cylinder The block portion 1 is formed with a boss portion 24 having a tap hole into which the bolt 18 is screwed. Each boss portion 24 has a height lower than that of the lower horizontally elongated rib 20.

If the boss portion 24 extends above the lower horizontally elongated rib 20, when an external force is applied to the crankcase portion 3 and the crankcase portion 3 is deformed, the deformation is transmitted to the upper part of the cylinder 6 via the boss portion 24, and the cylinder 6 is deformed. However, if the boss portion 24 is set to a height lower than the lower horizontally long rib 20 as in the present embodiment, even if the crankcase portion 3 is deformed for some reason, it may be deformed. The deformation of the crankcase portion 3 is absorbed by the deformation at the lower part of the cylinder 6, and it is possible to prevent the entire cylinder from being deformed.

(3). Vertical rib A vertically long rib 26 parallel to the axis of the cylinder 6 is formed on a portion of the longitudinal side surface of the cylinder block portion 1 outside the inter-bore portion 25. The upper end of the vertically long rib 26 is connected to the cylinder head portion 2, and the lower end reaches the lower deck portion 15 of the cylinder block portion 1, and intersects the upper and lower horizontally long ribs 14 and 20. Therefore, the vertical and horizontal ribs 14, 20, 26 and the lower deck portion 15 form a grid structure, whereby the main body block exhibits high rigidity against twisting and bending.

An oil pit 27 is formed in the vertically long rib 26 on the exhaust side. The oil pit 27 is opened above the cylinder head portion 2 and also below the cylinder block portion 1. Since the oil pit 27 is formed by using the vertically long rib 26 for reinforcement, the structure of the cylinder block portion 1 can be simplified and the weight can be reduced accordingly. The vertically elongated rib 26 projects larger than the lower horizontally elongated rib 20. This is to maintain the straightness of the cylinder 6.

The vertically long rib 26 has a vertically long hole 28 that is not an oil pit 27. These holes 28 are used as an oil gallery, a blow-by gas passage, and the like.

Since the bolt 18 for fastening the crankcase portion 3 and the cylinder block portion 1 is arranged outside the portion where the left-right width of the cylinder 6 is the largest, the pulling force of the bolt 18 is the inter-bore portion 25. It is the lowest on the outside of. Therefore, in the absence of the vertically elongated ribs 26, the lower deck portion 15 of the cylinder block portion 1 has the lowest adhesion to the crankcase portion 3 at the outer portion of the inter-bore portion 25.

However, if the vertically elongated ribs 26 are provided as in the present embodiment, the lower deck portion 15 is prevented from bending and deforming at the outer portion of the bore-between portion 25, so that the pulling force of the bolt 18 is applied to the lower deck portion 15. Of these, it also acts strongly on the outer portion of the inter-bore portion 25. Therefore, the portion of the lower deck portion 15 below the vertically long rib 26 can be strongly adhered to the crankcase portion 3 to ensure high sealing performance in the oil pit 27 (without using a sealing ring such as an O-ring). It is possible to ensure high sealing performance.)

Although the embodiments of the present invention have been described above, the present invention can be embodied in various ways. For example, in the embodiment, two upper and lower horizontal ribs are formed on the longitudinal side surface of the cylinder block portion 1, but it is also possible to form another horizontally long rib between the upper horizontal rib 14 and the lower horizontal rib 20. ..

The invention of the present application can be embodied in a monoblock type main body block. Therefore, it can be used industrially.

1 Cylinder block part that constitutes the main body block 2 Cylinder head part that constitutes the main body block 3 Crankcase part 5 Crankshaft 6 Cylinder 14 Upper horizontal rib 15 Lower deck part of the cylinder block part 16 Upper deck part of the crankcase part 18 Crankcase block Bolt that fastens the part and the crankcase part 20 Lower horizontal rib 21 Piston 25 Between bores 26 Vertical rib 27 Oil drop hole

Claims (2)

It has a cylinder block portion in which a plurality of cylinders are arranged side by side in the direction of the crank axis, and a cylinder head portion in which an intake port and an exhaust port are formed corresponding to the cylinders. Is a continuous structure as one cast product,
The lower end of the cylinder block portion is located above the crankshaft, and a crankcase that rotatably holds the crankshaft is fixed to the lower surface of the cylinder block portion.
Further, in the longitudinal outer surface of the cylinder block portion, near or lower than the height position of the top surface of the piston at the bottom dead center, in a state of being integrally connected to the outer surface of each cylinder, in the crank axis direction. Long horizontal ribs are formed on the
The main block of a multi-cylinder internal combustion engine. A boss portion for fixing the crankcase with a bolt is formed in the lower portion of the longitudinal side surface of the cylinder block portion, and the upper end of the boss is at a position lower than the horizontally long rib.
The main body block of the multi-cylinder internal combustion engine according to claim 1.

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