JPS5969515A - Crankshaft in internal-combustion engine - Google Patents

Abstract

PURPOSE:To make the distribution of stress, by making the diameter of a crankpin at the side distance away from the output driving part of a crankshaft smaller than that of a crankpin at the output driving part side, in case of such a crankshaft as being provided with plural crankpins in an axial direction. CONSTITUTION:A crankshaft 1 is installed with an output gear 2 at the central part, and plural crankpins 3a-3d are set up in an axial direction. In this case, a diameter D of each of crankpins 3b and 3c at the nearest position at both sides of the output gear 2 is made to be smaller than that a diameter (d) of each of crankpins 3a and 3d at both end parts. For example, (d) is set to a thickness of about 0.8D-0.9D in relationship. With this, stress in a portion being high in a stress value centering on the output gear 2 of the crankshaft 1 so far is lowered down to some extent, while the stress value in both end parts of the crankshaft 1 excessively low so far is raised up whereby the crankshaft 1 whose stress distribution is equal as a whole can be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a crankshaft for an internal combustion engine, and more particularly to a crankshaft for a multi-cylinder engine, in which the diameter of the crankpin is set to be unequal depending on the stress value to be borne. It is related to the axis.

One way to improve the output of an engine is to reduce the mass of the reciprocating and rotating parts of the engine and reduce frictional resistance. Considering the crankshaft, which is the main part of the engine, from the perspective of mass reduction, etc., conventionally, in the case of a multi-cylinder engine, all crankshaft diameters of the crank pins are set to be the same. Not taken into consideration.

In a crankshaft using such crank pins of the same diameter, for example, when analyzing the stress when the output is extracted from the center of the crankshaft, it is found that the stress on the crankshaft near the output drive section is shown by the dashed line A in Fig. The pin is approaching the allowable stress value, which is the limit, but the crank pins at both ends away from the crankshaft are receiving stress that is only slightly below the limit stress value, and the crank pin at the position far from the output drive part is If you look at it, it has been given excessive load-bearing performance.

Therefore, in view of the above points, the present invention aims to make the diameter of the crankbin even thinner, especially at both ends separated from the output drive section, which have been given excessive strength, so that the overall stress distribution is averaged. It is something that In other words, in a crankshaft of an internal combustion engine in which two or more crankbins are provided in the axial direction, the diameter of the crankbin at a position away from the output drive section of the crankshaft is equal to the diameter of the crankbin located on the output drive section side. It is configured to be smaller than the diameter.

The present invention will be specifically described below based on an illustrated embodiment. As shown in FIG. 1, a crankshaft 1 is provided with an output gear 2 serving as an output drive section at its center. The crank angle of this embodiment is a so-called 360-degree crank, and is slightly different from that of a parallel or in-line 4-cylinder, but this is an elliptical piston type and cylinder that has already been developed by the applicant. This is because it is applied to a four-cylinder engine equipped with a type (1). Needless to say, the present invention can be applied to any appropriate engine equipped with at least two or more crank bins, such as a conventional 180 degree crank type or a 120 degree crank found in three-cylinder engines. However, in this embodiment, four crank bins 3a, 3bl 3
0 and 3d are assembled to the crankshaft 1,
Their diameters have the following relationship: That is, with respect to the output gear 2 disposed at the center of the crankshaft 1, the diameter of the crank pins 3b, 3c at the closest positions on both sides of the output gear 2, and the diameter of the crank pins 3a, 3 at both ends further apart from this.
(Comparing the diameter d of 1, the diameter d should be smaller than the diameter.
Set to the thickness of the relationship. In FIG. 1, reference numeral 4 indicates a connecting rod, and 5 indicates a piston. The crankshaft 1 is provided with an oil supply hole 6 cut into the large end of the connecting rod 40, a journal bearing, etc.

Since the present invention is configured in this manner, the stress level in the part where it was conventionally high, centering on the drive output part of the crank, is reduced, as shown by @H in Figure 2, and the stress that was conventionally excessive The idea was to obtain a crankshaft with an equal stress distribution over the entire crankshaft, since the stress value at the crank bins located at both ends of the crank increased, which was low.

In other words, in the case of this embodiment, setting the pin diameter of the crank pins 3a and 3(i) located at both ends to be small will not affect the stress on the central portion, and the stress will be equal as a whole. The reason why the stress value at the center of the knob can be reduced is that by reducing the weight of the crank bins at both ends, the stress distribution as a whole to the center of the crankshaft is reduced. Uniform stress distribution can contribute to improving the durability of the crankshaft.Furthermore, the small diameter of the crankshaft can also reduce crank friction during engine operation. In addition, by reducing the weight of the large end of the connecting rod and the balance weight, the overall weight, or so-called crank mass, is reduced, which also makes it possible to achieve high output.

In other words, reducing the diameter of the crankbin at a position away from the output drive section not only reduces the weight of the crankbin itself, but also reduces the amount of balance weight in the crank web and the weight of the large end of the connecting rod. These synergistic weight reductions can be achieved.

In this example, the output drive unit is set at the center of the crankshaft in an engine with four crank bins, that is, normally a parallel or '11N in-line 4-cylinder engine, or a parallel-transfer or parallel type 8-cylinder engine. However, in the case of a type that extracts output from the end of the crankshaft, the diameter of the crank pin can be designed to gradually decrease as the position of the crank pin moves away from the output drive part.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view showing a crankshaft in an internal combustion engine of the present invention, and FIG. 2 is a diagram showing stress distribution of the crankshaft shown in FIG. 1. 1 is the crankshaft, 2 is the output gear which is the driving part, 3a +
3 b r 3 c and 3 d are crank bins. Patent applicant: Honda Motor Co., Ltd. Attorney, Patent Attorney, Civil Engineering, Toden - Department, Department of Civil Engineering, Kido -
Production amount Shige Hattori
Toku-Ichikenya $ 1982 Procedural Amendment IJ114r+ 1988 Patent Application No. 178741 2, Title of invention 4, Agent 6, Number of inventions increased by amendment 7, Drawing subject to amendment 8, Amendment In the drawings, the reference numeral r36J'ft in Figure 1 has been corrected in red. Above (1) -・Separate plastics

Claims (1)

[Claims] 1. In a crankshaft of an internal combustion engine in which two or more crank pins are provided in the axial direction, the diameter of the crank pin located away from the output drive part of the crankshaft is the diameter of the crank pin located on the output drive part side. A crankshaft for an internal combustion engine, characterized in that the crankshaft is configured to have a diameter smaller than that of the crankshaft.