JPH0435565Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an improvement in the cylinder block structure of an engine.

(Prior art and its problems) An engine can be seen as a type of elastic body.
As the engine operates, it is common for one end and the other end in the direction of the engine output shaft to undergo torsional deformation, that is, torsional vibration such that they are twisted in opposite directions. When a heavy transmission is connected in series with the engine in the output shaft direction, this torsional vibration tends to become more noticeable as torsional vibration of the power plant system.

In order to reduce such torsional vibrations, it is sufficient to increase the rigidity of the engine cylinder block, that is, the torsional rigidity. For this purpose, for example, the left and right side walls of the cylinder block in a cross section perpendicular to the engine output shaft are connected to each other. Among the parts,
It is conceivable to further increase the wall thickness of the bottom deck part, which has a relatively large wall pressure.
-Refer to Publication No. 82458).

However, simply increasing the thickness of the bottom deck portion increases the weight of the engine, which is difficult to adopt in the current situation where there is a strong demand for lightweight engines.

Therefore, an object of the present invention is to provide an engine cylinder block structure that can increase torsional rigidity without increasing weight.

(Means and effects for solving the problems) In order to achieve the above-mentioned object, the present invention has the following configuration. That is, the shape of the bottom deck part is formed in an arcuate shape in a cross section perpendicular to the crankshaft so as to be concave toward the torsion center axis of the engine that extends substantially parallel to the crankshaft. .

With this configuration, the arc-shaped bottom deck part becomes as if it constitutes a part of a cylindrical surface formed around the torsion center axis, and the torsion around this torsion center axis The effect of resisting deformation, that is, the torsional rigidity, is significantly improved.

(Embodiments) Examples of the present invention will be described below with reference to the attached drawings.

In FIG. 1, a cylinder block A is used for a reciprocating type in-line multi-cylinder engine, and as is known, its upper part is a cylinder part 1, and its lower part is a skirt part 2. Part 2
However, it has a bearing portion 4 for holding an engine output shaft (crankshaft) 3.

As is well known, the cylinder portion 1 has a cylinder bore (not shown) into which a piston is inserted, and in the embodiment, a water jacket 5 is provided between the cylinder bores. The left and right side walls of the cylinder portion 1, that is, a pair of left and right side walls 1a and 1b in a cross section perpendicular to the engine output shaft direction (direction perpendicular to the plane of the first drawing) are connected at their lower portions by a bottom deck portion 6. The bottom deck portion 6 also constitutes the bottom wall of the water jacket 5 mentioned above.

The bottom deck portion 6 has a cross-sectional shape in a direction perpendicular to the engine output shaft 3 that abuts the engine output shaft 3.
It is formed in an arcuate shape convex toward , and its wall thickness is almost the same as that of the conventional flat plate. That is, the torsion center axis of an engine constructed using such a cylinder block A is as shown by O in FIG.
Generally, the bottom deck part 6 is located considerably above the bottom deck part 6, and therefore, the bottom deck part 6 is formed into an arc shape so as to be concave toward the torsion center axis O.

As mentioned above, since the bottom deck part 6 is formed in an arc shape so as to be concave toward the torsion center axis O, the torsional rigidity against the force of twisting about the torsion axis O is increased. , significantly improved. That is, as shown in principle in FIGS. 2 and 3, for torsional forces F and -F centered on the torsion center axis O, the cross section will be centered on the torsion center axis O as shown in FIG. An arcuate shape forming a part of a cylindrical surface centered at O is more difficult to deform than a flat plate shape as shown in FIG. Therefore, compared to the case where the bottom deck part 6 is made into a flat plate shape as shown by the first dotted chain line, even if it has the same wall thickness (same weight) as this flat plate part, it is made into an arc shape. The bottom deck portion 6 is more difficult to twist and deform. In other words, when the weight of the bottom deck part 6 is the same, by making the bottom deck part 6 arc-shaped, the torsional rigidity is significantly increased compared to the conventional one which is flat-shaped. becomes.

(Effects of the invention) As is clear from the above, the invention has the following effects:
The torsional rigidity of the cylinder block can be greatly increased while suppressing weight increase.

In particular, the present invention can be easily implemented since the bottom deck portion only needs to have an arcuate shape.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing an embodiment of the present invention.
FIGS. 2 and 3 are perspective views schematically showing the principle of increasing torsional rigidity according to the present invention in comparison with conventional ones. O...Torsion center axis, A...Cylinder block, 1...Cylinder part, 2...Skirt part, 3...
...Engine output shaft, 6...Bottom deck part.

Claims (1)

[Scope of utility model registration request] An engine characterized in that the shape of the bottom deck portion is formed in an arcuate shape in a cross section perpendicular to the crankshaft so as to be concave toward a torsion center axis of the engine extending substantially parallel to the crankshaft. Cylinder block structure.