JPS61252856A - Multicylinder engine - Google Patents

Abstract

PURPOSE:To increase the rigidity as a whole and reduce the generation of vibration and noise by arranging the curved surfaces having a plurality of semicircular forms arranged on the lower side wall of a cylinder block and on the side wall of an oil pan so that each node on the both curved surfaces does not coincide with. CONSTITUTION:A crankcase 1a and an oil pan 6 which have the continuous semicircular curved surfaces 4 and 8, respectively, are arranged in discrepancy so that the node part 5 on the curved surface 4 and the node part 11 of the curved surface 8 do not coincide, viewed from the upper, and fastened by bolts through a flange 9. Therefore,each node part between the curved surfaces is reinforced by the other, and the weak part on the side wall is eliminated. Therefore, the rigidity of the whole as the assembled body of a cylinder block and the oil pan is incressed, and the place which is deformed locally is eliminated. Therefore, the transverse bending vibration is suppressed, and the generation of the vibration transmitted onto chassis and the noise due to the vibration can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multi-cylinder engine, and more particularly to an engine structure in which a continuous semicircular curved surface is formed on the side wall along the direction in which the cylinders are arranged. .

This is used in the field of multi-cylinder engines where multiple cylinders are arranged in a row.

[Prior art]

In addition to the combustion noise from the engine, the noise generated by automobiles comes from the vibrations generated by the engine.

Engine vibrations are caused by gas pressure during compression and expansion strokes and inertia of pistons, etc., and the vibrations are transmitted to the vehicle body via the mount bracket that supports the crankcase. Therefore, vibrations are transmitted from the frame and each panel to the interior of the vehicle, and when the vibration noise enters the interior of the vehicle as noise, it causes problems such as hindering ride comfort.

In order to suppress engine vibration, it is sufficient to increase the rigidity of the cylinder block, etc. For example, in a multi-cylinder engine, the cylinder block may have unevenness, and the crankcase connected to the bottom of the cylinder block may also have continuous unevenness. may be formed. In addition, various measures have been taken, such as forming ribs on the side walls along the direction in which the cylinders are arranged. In addition to such improvements in the rigidity of the cylinder block, there are also systems that increase the rigidity of the oil pan itself, which is fastened below the crankcase. For example, Japanese Utility Model Publication No. 57-144248 proposes an oil pan in which an uneven bulge made of a combination of a plurality of spherical surfaces is formed on the side and bottom surfaces of the oil pan. The oil pan is manufactured by sheet metal processing a thin iron plate, and by creating a curved surface with spherical irregularities, membrane vibration of the thin plate is suppressed and the vibration level is reduced. Therefore, when such an oil pan is attached to the cylinder block, the rigidity near the crankcase can be increased, which can contribute to reducing vibrations of the cylinder block.

By the way, cylinder blocks generally have high rigidity in the direction in which the piston reciprocates, and are able to sufficiently withstand even if an excitation force is applied in that direction, so even if vibration occurs, it can be ignored to some extent. can. However, in a multi-cylinder engine, the cylinders are thinner and longer in the direction in which they are arranged, so when a lateral bending force is applied, the resulting vibration appears more prominently than in the vertical direction.

As an example of the above-mentioned crankcase having continuous irregularities, a curved surface having a plurality of semicircular arcs that are continuous along the cylinder arrangement direction and arranged in a plan view may be formed on the lower side wall of the crankcase. In that case, although the semicircular arc improves the overall rigidity of the crankcase and cylinder block,
When viewed locally, the node, which is a depression between two semicircular arcs, becomes weaker than the circular arc. Therefore, when a lateral bending force is applied, a bend occurs at that joint, as shown in Figure 5.
The side wall IA of the cylinder block vibrates while deforming from the state shown by the solid line P to the one-dot chain line Q or the two-dot chain line R. As long as such deformation occurs, engine vibration will not be suppressed, and even if an oil pan with improved rigidity as described above is fastened to the bottom of the crankcase,
The joints still remain as relatively weak areas. Therefore, it is not sufficient to suppress lateral bending vibration by taking measures for individual parts, and a comprehensive solution is desired.

[Purpose of the invention]

The present invention was made in view of the above-mentioned problems, and its purpose is to compensate for the weakness of joints when curved surfaces are formed to increase the rigidity of the cylinder block, and to improve the rigidity of the cylinder block and oil pan. To provide a multi-cylinder engine capable of increasing the rigidity of the whole as a combination body, eliminating parts where local deformation tends to occur, and thereby suppressing engine vibration and reducing noise generation.

[Structure of the invention]

The multi-cylinder engine of the present invention is characterized by forming a curved surface on the lower side wall of the cylinder block including the crankcase, which is continuous along the direction in which the cylinders are arranged and has a plurality of semicircular arcs lined up when viewed from above the cylinder axis. , a curved surface is formed on the side wall of the oil pan that is fastened to the lower part of the crankcase, and is continuous along the direction in which the cylinders are arranged, and is lined with a plurality of semicircular arcs when viewed from above the cylinder axis. The joints of the oil pan and the joints of the curved surface of the oil pan are arranged so that they do not coincide with each other when viewed from above the cylinder axis.

〔Example〕

Hereinafter, the present invention will be explained in detail based on examples thereof.

FIG. 1 is an external perspective view of a multi-cylinder engine to which the present invention is applied. A cylinder block 1 is composed of a crank case 1a and a cylinder case 1b, and four cylinder bores 2 are arranged in a line in the left-right direction in the figure. 0 example is cylinder 3
A curved surface 4 of a semicircular arc is formed in correspondence with each cylinder, and this is continued along the arrangement direction of the cylinders 3 via a joint 5 which is a recess, as shown in the bottom view of FIG. ing.

When this curved surface 4 is not subjected to lateral bending force, the above-mentioned fifth
As shown by the solid line P shown in the figure, they are lined up almost straight without different angles. In the crankcase 1a, the side wall IA has a curved surface of 4 m.
However, in the cylinder case 1b, a similar semicircular curved surface 4n is formed on the side wall IB, and both are continuous in the vertical direction as well.

As described above, such a curved surface 4 improves the rigidity of the crankcase 1a and the cylinder case ib compared to the case where the curved surface 4 is not formed. but,
There is a large opening under the crankcase 1a to which the oil pan 6 is attached, and an open lower part is provided for the bearing of the crankshaft, so the rigidity at the open end cannot necessarily be said to be high. Moreover, the curved surface 4
Each node 5 in between is necessarily a curved surface 4 of a semicircular arc.
As mentioned in the prior art section, it is weaker than .

On the other hand, a side wall 6A of the oil pan 6 fastened below the crankcase 1a has a curved surface 8 that is continuous along the arrangement direction of the cylinders 3 and is lined with a plurality of semicircular arcs as shown in the plan view of FIG. is formed.

The oil pan 6 itself is made of a thin iron plate, and a flange 9 is formed around the upper part to be a mating surface with the crankcase 1a, and holes 10 for fastening bolts are bored at positions corresponding to the joints 11. . In this way, the oil pan 6 has increased rigidity just like the crankcase 1a, and even if subjected to lateral bending force, it can withstand membrane vibration on its own, except for bending at the joint 11. Become.

The crankcase 1a and the oil pan 6 each have a curved surface 4°8 made of continuous semicircular arcs, and each node 5 of the curved surface 4 of the crankcase 1a and the curved surface 8 of the oil pan 6 are connected to each other. The parts 11 are arranged at different positions as shown in FIG. 1 so that they do not coincide with each other when viewed from above the cylinder axis, and are fastened with bolts via the flange 9. Note that the pitch of each node of the semicircular arc in the oil pan 6 is the same as that of the crankcase 1a, and the pitch of one adjacent node, for example, 5.5, is made the same as that of the crankcase 1a, and It is most preferable that the other joint portion 11 be arranged in the center. However, as will be explained later, if the two cylinder parts do not match, the weak joints of each other will be strengthened by the curved surface of the other semicircular arc, so at least the joints of the crankcase and the oil If the joints of the bread are arranged so that they do not overlap, the intended purpose will be achieved.

Note that if a rib 12 extending in the direction in which the cylinders 3 are arranged in FIG. 1 is formed on the crankcase 1a, the rigidity at that location can be further improved.

According to the embodiment with such a configuration, even if a lateral bending force is applied, the curved surface 4° 8 formed on the crankcase 1a or the cylinder case 1b and the oil pan 6 will not bend the other joint 11.
, 5 is compensated for, and the parts with low rigidity in the entire engine assembly are reinforced. The source of vibration in the engine is the gas pressure during the combustion stroke, and the inertial force of the piston, etc., which is lowered by the gas pressure. Although the excitation force acting on the engine is greatest in the vertical direction, it is sufficiently counteracted as described above, and based on this (vibrations are relatively small).

On the other hand, when the piston descends, the connecting rod is tilted from a vertical position, so a horizontal component force is generated due to the inertia of the piston. This force acts through the crankshaft to cause the cylinder block 1 to swing laterally, and this force is generated periodically within each cylinder, causing the cylinder block 1 to move as shown by lines Q and R in Figure 5. trying to transform it into However, the knots 5, which are weak parts of the cylinder case 1b and crankcase 1a, are located at the curved surface 8 of the oil pan 6, as shown in FIG. 4 when viewed from above the cylinder shaft.
crankcase 1.
Even if bending is likely to occur at the node 5 of the oil pan 6, the curved surface 8 of the oil pan 6 will counteract it. On the other hand, the curved surface 4 of the crankcase 1a is connected to the knot 11 of the oil pan.
will complement the strength.

Therefore, even if a lateral bending force is applied, the curved surfaces 4.8, which are formed independently, mutually act to increase rigidity when combined. In the crankcase 1a,
There is a large opening to form a space with the oil pan 6 and an open lower part for the crankshaft bearing, and although it is highly rigid and difficult to remove, it is compensated for by the oil pan 6, and the oil has a thin plate structure. The strength of the pan 6 is also supplemented by the crankcase 1a. Therefore, it exhibits an extremely effective vibration suppressing effect against the lateral bending vibration caused by the force generated by the engine, especially the lateral bending mode of 800 to 1000 Hz, which greatly influences the generation of noise. This reduces the vibrations transmitted from the engine to the vehicle body, reduces the vibration of the vehicle body by the engine, and significantly reduces noise generation.

〔Effect of the invention〕

As can be seen from the description of the embodiments above, the present invention forms a curved surface in which a plurality of semicircular arcs are arranged on the lower side wall of the cylinder block, and a curved surface in which a plurality of semicircular arcs are arranged in the side wall of the oil pan. However, since the joints of both curved surfaces are arranged so as not to coincide with each other, the joints between the curved surfaces are reinforced by the other curved surface, and weak points on the side wall are eliminated. Therefore, the overall rigidity of the combination of the cylinder block and oil pan is increased, and there are no significant local deformations.As a result, lateral bending vibrations of the cylinder block and oil pan are suppressed. It is possible to reduce the vibration transmitted to the vehicle body and the noise generated by it.

[Brief explanation of drawings]

Fig. 1 is an overall perspective view of a multi-cylinder engine to which the present invention is applied, Fig. 2 is a bottom view showing the fastening surface of the crankcase with the oil pan, Fig. 3 is a plan view of the oil pan, and Fig. 4
The figure is a schematic layout showing the overlap between one curved surface and the other node, and FIG. 5 is a schematic diagram showing lateral bending vibration. 1--Cylinder block, 1a--Crank case, 1b--Cylinder case, IA, IB, 6A-Side wall,
3-Cylinder, 4.8-Curved surface, 6-Oil pan, 5.
11- Node.

Claims (1)

[Claims] (1) On the lower side wall of the cylinder block including the crankcase, a curved surface is formed that is continuous along the direction in which the cylinders are arranged and has a plurality of semicircular arcs lined up when viewed from above the cylinder axis. A curved surface is formed on a side wall of the oil pan to be fastened, and is continuous along the arrangement direction of the cylinders and has a plurality of semicircular arcs lined up when viewed from above the cylinder axis, and each node of the curved surface in the crankcase. and each node of the curved surface of the oil pan are arranged so that they do not coincide when viewed from above the cylinder axis.