JPH0932843A - Crankshaft for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve rigidity of a crank shaft so as to reduce generation of vibration of the crank shaft by arranging a padding part on a crank pin side from the center of a crank so as to enlarge the thickness of a crank web in a small thickness crank web and the crank web which is arranged opposing to the small thickness crank web. SOLUTION: In a crankshaft 2, first and second thickness parts 14-1, 14-2 are arranged on a second and seventh crank webs 6-2, 6-7 opposing to a first and eight crank webs 6-1, 6-9 whose minimum cross section is a small size comparatively, and thereby, the rigidity is increased. Even if a first crank pin 8-1 is positioned upward and a load from a piston is acted on the first crank pin 8-1, the occurrence of tipping is reduced on the first and second crank webs 6-1, 6-2 by existence of a first thickness part 14-1. Same effect is also applied on a fourth crank pin 8-4 side by a second thickness part 14-2. It is thus possible to reduce vibration of the crankshaft 2 in a small degree, and improve fatigue rigidity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crankshaft for an internal combustion engine, and more particularly to a crankshaft for an internal combustion engine capable of improving rigidity.

[0002]

2. Description of the Related Art In an internal combustion engine, a crankshaft is rotatably supported by a cylinder block so as to be rotated by the reciprocating motion of a piston. This crankshaft comprises a crank journal, a crank web and a crank pin.

That is, as shown in FIGS. 5 to 7, the crankshaft 102 is used for an internal combustion engine (not shown) for four cylinders, and the first to fifth crank journals 10 are used.
4-1 to 104-5 and the first to eighth crank webs (#
1 to # 8) 106-1 to 106-8 and first to fourth crank pins 108-1 to 108-5. The crankshaft 102 has the first crank journal 10
An oil pump driving sprocket 110 is provided at 4-1 and a crank angle sensor plate 112 is provided at the eighth crank web 106-8. Therefore, the first
In the first and second crank webs 106-1 and 106-2 facing each other with the crank pin 108-1 interposed therebetween, the first
The thickness t1 of the crank web 106-1 is formed smaller than the thickness t2 of the second crank web 106-2, and the seventh and eighth crank webs 106-, which face each other with the fourth crank pin 108-4 interposed therebetween, are formed. 7 and 106-8, the thickness t8 of the eighth crank web 106-8 is the seventh.
It is formed to be smaller than the thickness t7 of the crank web 106-7.

Further, the rigidity of the crankshaft 102 is determined by the minimum cross section S2, S2 ... Between each crank journal and each crankpin. In addition, in FIG. 7, the symbol C is the center of the crank.

Further, as the structure of such a crankshaft, for example, Japanese Utility Model Laid-Open No. 60-121522,
It is disclosed in Japanese Utility Model Laid-Open No. 1-288607. Japanese Utility Model Laid-Open No. 60-121522 discloses an assembled crankshaft in which the crank web on the crank pin insertion hole side is made thicker than the other crank web, and the outer end of the crank pin insertion hole is formed. Is blocked. What is described in Japanese Utility Model Publication No. 1-288607 is
In an assembled crankshaft, a thick crank web is arranged on the left and right outer sides of a crank shaft, and a thin crank web is arranged inside the crank web, and a crank pin is press-fitted therein.

[0006]

However, in the conventional crankshaft, the first crank journal is provided with the sprocket for driving the oil pump, and the eighth crank web is provided with the crank angle sensor plate.
The thicknesses t1 and t8 of the first and eighth crank webs must be smaller than the thicknesses t2 and t7 of the other second and seventh crank webs on the opposite side,
Therefore, the rigidity of the crankshaft is reduced, and
There is a disadvantage that the vibration of the crankshaft is greatly generated and the fatigue strength is lowered.

Further, as shown in FIG. 7, for example, when the first crank pin 108-1 is located above,
When a load W from a piston (not shown) acts on the crank pin 108-1, the first and second crank webs 106
-1, 106-2 has a disadvantage that a large amount of sagging easily occurs.

[0008]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention comprises a crank journal, a crank web, and a crank pin, and the thickness of the crank web facing each other with the crank pin interposed therebetween is In different crankshafts for internal combustion engines, the other crank webs on the opposite side of the crank webs of a smaller thickness are thicker on the crank pin side than the crank center so as to increase the thickness of the other crank webs. It is characterized by having a section.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, even if the thickness of one crank web facing the crank shaft is small, the thickness of the crank web on the crank pin side of the crank web having a large thickness on the opposite side is increased by the built-up portion. By making it larger, the rigidity of the crankshaft is improved, the vibration of the crankshaft is reduced, and the fatigue strength is improved.
The deflection of the crankshaft can be reduced.

[0010]

Embodiments of the present invention will be described in detail and specifically with reference to the drawings. 1 to 4 show an embodiment of the present invention. In FIG. 1, reference numeral 2 is a crankshaft used in a four-cylinder internal combustion engine (not shown).

The crankshaft 2 includes first to fifth crank journals 4-1 to 4-5, first to eighth crank webs (# 1 to # 8) 6-1 to 6-8, and a first crankshaft. ~ Fourth
It is composed of crank pins 8-1 to 8-4.

In this crankshaft 2, in order to provide the sprocket 10 for driving the oil pump on the first crank journal 4-1 on the one end side, the thickness t1 of the first crank web 6-1 is set to the second crank web 6-1. The thickness t2 of the sixth crank web 6-8 is smaller than the thickness t2 of the sixth crank web 6-8, and the thickness t8 of the eighth crank web 6-8 is the seventh crank web in order to provide the crank angle sensor plate 12 on the fifth crank journal 4-5 side. Formed to be smaller than the thickness t7 of 6-7,
And other 3rd-5th crank webs 6-3-6
-6 thicknesses t3 to t6 are formed to be substantially the same.

Further, in order to ensure a predetermined rigidity of the crankshaft 2, the first crank journal 4-1 and the first crank journal 4-1 are provided.
A predetermined first minimum cross section S1 is set between the crank pins 8-1, and a predetermined second minimum cross section S2 is set between the first crank pin 8-1 and the second crank journal 4-2.
A predetermined third minimum section S3 is set between the crank journal 4-2 and the second crank pin 8-2, and a predetermined fourth minimum section S4 is set between the second crank pin 8-2 and the third crank journal 4-3. Is set, the third crank journal 4
-3 and the third crank pin 8-3 are set with a predetermined fifth minimum cross section S5, and the third crank pin 8-3 and the fourth crank journal 4-4 are set with a predetermined sixth minimum cross section S6. , A predetermined seventh minimum cross section S7 is set between the fourth crank journal 4-4 and the fourth crank pin 8-4, and
A predetermined eighth minimum cross section S3 is set between the crank pin 8-4 and the fifth crank journal 4-5.

As described above, when the thicknesses t1 and t8 of the first and eighth crank webs are made smaller than the thicknesses t2 and t7 of the other second and seventh crank webs on the opposite side, the rigidity of the crankshaft 2 is increased. Therefore, in this embodiment,
The second crank web 6-2 opposite to the first crank web 6-1 is provided with a first built-up portion 14-1 having a predetermined thickness A on the first crank pin 8-1 side with respect to the crank center C. .
As shown in FIG. 3, the first built-up portion 14-1 is formed in an arc shape above the center C of the crank and along the first crank pin 8-1.

Similarly, the eighth crank web 6-8
The seventh crank web 6-7 on the opposite side is provided with a second built-up portion 14-2 having a predetermined thickness A on the fourth crank pin 8-4 side with respect to the crank center C. This second built-up portion 14-2
Has a shape substantially similar to that of the first thick portion 14-1.

Next, the operation of this embodiment will be described.

In the crankshaft 2, the first and eighth crank webs 6-1 and 6 each having a relatively small minimum cross section.
Second and seventh crank webs 6-2, 6- on the side opposite to -8
Since the first and second built-up portions 14-1 and 14-2 are provided at 7, the rigidity thereof becomes high.

As shown in FIG. 4, for example, even if the first crank pin 8-1 is located above and a load W from a piston (not shown) acts on the first crank pin 8-1, The presence of the first built-up portion 14-1 can reduce the occurrence of sagging in the first and second crank webs 6-1 and 6-2. Further, also on the side of the fourth crankpin 8-4, the same effect can be obtained by the second built-up portion 14-2.

As a result, the vibration of the crankshaft 2 can be suppressed small and the fatigue strength can be improved.

In the above embodiment, since the oil pump driving sprocket 10 and the crank angle sensor plate 12 are provided on both ends of the crankshaft 2, the first and eighth crank webs 6-1 and 6- are provided. Thickness t 8
1, t8 is reduced to make the first and second built-up portions 14-1, 14
-2 is provided, but parts such as the sprocket 10 for driving the oil pump are provided only on one end side of the crankshaft 2, and when such parts are not provided on the other end side of the crankshaft 2, the overlay portion is provided. It is also possible to provide 14 at only one location.

[0021]

As is apparent from the above detailed description, according to the present invention, the other crank webs on the side opposite to the crank webs having the smaller thickness of the crank shaft are provided with the thickness of the other crank webs. By providing a built-up portion on the crank pin side from the center of the crank so as to make it larger, the rigidity of the crankshaft is improved, the occurrence of vibration of the crankshaft is reduced, and the fatigue strength is improved. Shaft sagging can be reduced.

[Brief description of drawings]

FIG. 1 is a front view of a crankshaft.

FIG. 2 is a right side view of a crankshaft.

FIG. 3 is a schematic sectional view of a crankshaft.

FIG. 4 is a skeleton diagram of the crankshaft under a load.

FIG. 5 is a front view of a conventional crankshaft.

FIG. 6 is a right side view of a conventional crankshaft.

FIG. 7 is a skeleton diagram of a state where a load is applied to a conventional crankshaft.

[Explanation of symbols]

 2 Crank shaft 4 Crank journal 6 Crank web 8 Crank pin 14 Overlay part

Claims (1)

[Claims] 1. A crankshaft for an internal combustion engine, comprising a crank journal, a crank web, and a crank pin, wherein the crank webs facing each other with the crank pin sandwiched therebetween have different thicknesses. A crankshaft for an internal combustion engine, wherein the other crank web is provided with a build-up portion on the crank pin side with respect to the center of the crank so as to increase the thickness of the other crank web.