JPH11247836A - Crankshaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crankshaft for an in-line six cylinder engine light, excellent in strength and excellent in durability and reliability. SOLUTION: Fatigue strength is improved by hardening a surface by carrying out shot peening or rolling pressure working after setting width of front and rear web parts connected to a crank pin 12 corresponding to cylinders with a distance of 360 degrees in ignition order and positionally adjacent to each other larger than width of a web part 14 connected to the crankpin 12 corresponding to other cylinders or respectively carrying out induction hardening on a round part of a connecting part of the crankpin 12 and the web part 14 of a specific cylinder and a round part of a connecting part of the same web part 14 and a crank journal 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a crankshaft for an in-line six-cylinder engine.

[0002]

2. Description of the Related Art In a conventional inline six-cylinder engine, a crankshaft has a front end (cooling fan side).
From the first cylinder to the sixth cylinder at the rear end (flywheel side), the width of the web portion connecting the crank pin and the crank journal of each cylinder is formed substantially equal, and the width of the crank pin and the web portion is substantially equal. In the connection portion and the R portion in the connection portion between the web and the crank journal,
Substantially the same surface treatment such as induction hardening is performed.

[0003]

However, in a crankshaft of an in-line six-cylinder engine, a connecting portion between a crankpin and a web portion corresponding to each cylinder which usually forms a weak point portion of the crankshaft, and the web portion, The stress generated in the R portion at the connection portion with the crank journal is not uniform in all of the first to sixth cylinders, and the connection portion between the crank pin and the web portion and the web portion and the crank journal in some specific cylinders are not provided. In the R portion of the connecting portion, a larger stress amplitude is generated than the corresponding R portion of the other cylinder. Therefore, the strength margin of the connecting portion R of the specific cylinder is small, and cracks and the like may occur under severe operating conditions. There was a problem that damage easily occurred.

[0004] The present invention has been made in view of the above circumstances, and in the crankshaft of an inline 6-cylinder engine, a connection portion between the crankpin and the web portion of the specific cylinder and a connection portion between the web portion and the crank journal. The strength of
By increasing the strength of the corresponding connecting parts in the other cylinders, the strength of the entire crankshaft can be effectively improved without problems such as a large weight increase, and durability and reliability are excellent. It is a primary object to provide a crankshaft that has been developed.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a crankshaft of an in-line six-cylinder engine, which is ignited at a crank angle of 360 degrees and corresponds to two adjacent cylinders. The width of the web part connecting the crankpin and the crank journal is set to be larger than the width of the web part connecting the crankpin and the crank journal corresponding to the other cylinder, or the width of the crankpin and the web corresponding to the two cylinders is set. The crankshaft is characterized in that, after induction hardening, the shot peening or the roll pressing is performed on the connection portion with the portion and the R portion of the connection portion between the web and the crank journal. It is a suggestion.

According to the present invention, in a crankshaft of an inline six-cylinder engine, a connection portion between a crank pin and a web portion of two cylinders which ignite at a crank angle of 360 degrees and are adjacent to each other, and the web portion are provided. Based on the finding that a larger stress amplitude occurs at the connection between the cylinder and the journal than at the corresponding connection of the other cylinders, the width of the web connected to the crankpins corresponding to the two cylinders, After increasing the dimension in the direction perpendicular to the axis of the shaft, or after performing induction hardening on the connecting portion between the crankpin and the web portion and the R portion of the connecting portion between the web and the crank journal, shot peening or rolling is performed. By increasing the fatigue strength of each R part by applying pressure processing, the strength of the entire crankshaft can be effectively improved. That.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to FIGS. First, in FIG. 1, reference numeral 10 generally indicates a crankshaft of an in-line six-cylinder engine. The crankshaft 10 extends from a front end on a cooling fan side to a rear end on a flywheel side and has a first cylinder # 1 to a sixth cylinder. Crankpins 12 corresponding to cylinders # 6 are provided. Each crank pin 12
Each is connected to a crank journal 16 via a pair of front and rear web portions 14. The above crank journal 16
Are of course arranged on the crankshaft line OO.

FIG. 2 is a front view of the front end of the crankshaft 10. As shown by a two-dot chain line in FIG. 2, the crankpins 12 of the first and sixth cylinders # 1 and # 6, The crankpins 12 of the second and fifth cylinders # 2 and # 5 and the crankpins 12 of the third and fourth cylinders # 3 and # 4 are respectively arranged on the same axis, and around the crank axis OO. They are arranged on concentric circles with an angle interval of 120 degrees. A side view of FIG. 3 in which the crankshaft portion of the third cylinder # 3 is extracted and shown for an arbitrary one cylinder, for example, and IV-I of FIG.
As shown in the cross-sectional view along the line V, a front R portion _Pf and a rear R portion _Pr are formed at a connection portion between the crank pin 12 and the front and rear web portions 14, and the front and rear crank journals are formed. The connection between the web part 16 and the web part 14 includes a front R part _Jf and a rear journal R part _{Jr, respectively.}
Are formed. As shown in FIG. 4, a balance weight 18 is formed integrally with the web portion 14, and the web portion 14 and the balance weight 1 are formed.
8, a lightening portion 20 for reducing the weight is formed.

The general ignition sequence of an inline 6-cylinder engine having the crankshaft 10 is as follows: # 1 → # 5 → # 3 → #
6 → # 2 → # 4 → (# 1). During the operation of the engine, when explosive combustion occurs in the first cylinder # 1 to the sixth cylinder # 6, the pressure due to the explosive combustion acts on the crankpin 12 via the piston and the connecting rod,
Further, it is transmitted to the crank journal 16 via the web portion 14. At this time, the R portions P _f and P _{r at} the connection portion between the crank pin 12 and the front and rear web portions 14 and the R portions J _f and J _r at the connection portion between the front and rear web portions 14 and the crank journal 16 are _added . Large stress is generated.

The first cylinder # 1, the second cylinder # 2, and the third cylinder # 3 when the six-cylinder engine is operating at almost full power.
7 to 9 show the stresses generated in the R portions P _f , P _r , J _f, and J _r . 7 to 9, each of the diagrams has a vertical axis representing the generated stress (kgf / mm).
² ) shows the state of occurrence of stress in each of the above-mentioned R portions of the corresponding crankshaft 10 by taking the cylinder ignited on the horizontal axis. For example, the first cylinder # 1 in FIG. 7, each R unit J _f at its explosive _combustion, J _r, respectively maximum stress is generated in the P _f and P _r unit, at the time of explosive combustion of the other cylinders, small Generates a stress in the opposite direction (for example, a small tensile stress when the maximum stress is a compressive stress).

[0011] Compared to FIGS As apparent, the maximum stress amplitude S ₀ is generated in each R portion of the crankshaft 10 corresponding to the third cylinder # 3 in FIG. this is,
Third cylinder # 3 and the ignition interval is in 360-degree spaced relation with the crank angle, and positionally in the opposite direction at the time of ignition of the fourth cylinder # 4 adjacent stress S _{1 (see} R portion J _f of FIG. 9 ) Are arranged in the first cylinder # 1 in FIG. 7 and the second cylinder # 2 in FIG. 8 at intervals in the direction of the crank axis, and have a cylinder angle of 360 degrees. Is greater than the stress in the opposite direction that occurs during ignition. Although not shown, the generated stress of each R portion of the crankshaft 10 corresponding to the fourth cylinder # 4 is the generated stress of the third cylinder # 3 and the generated stress of the crankshaft 10 corresponding to the fifth cylinder # 5. The stress generated in the R portion is the stress generated in the second cylinder # 2 and the crankshaft 10 corresponding to the sixth cylinder # 6.
The generated stress of each R portion is substantially the same as the generated stress of the first cylinder # 1.

FIG. 6 shows the stress amplitudes of the R portions J _f , P _f , _Pr and J _f of all six cylinders, including the measurement results of FIGS. 7 to 9 described above. From the figure, the ignition interval is 360 degrees in crank angle, and the stress amplitudes of the third and fourth cylinders adjacent to each other are sufficiently larger than the stress vibrations of the other cylinders, and thus have the necessary strength as a whole, In addition, in order to realize a lightweight and inexpensive crankshaft 10, means for reducing the stress amplitude of the stress generated in each R portion of the crankshaft corresponding to the third cylinder # 3 and the fourth cylinder # 4 is to be focused. It is effective to take.

As one of means for reducing the stress amplitude of each of the R portions of the crankshaft corresponding to the third cylinder # 3 and the fourth cylinder # 4, a crank pin 1 corresponding to these cylinders is used.
2 and the crank journal 16 by the width W of the web portion 14.
It is effective to increase (see FIG. 4). The width W of the web portion 14, divided by the half of the sum of the diameter _{D j} of the diameter _{D p} and the crank journal 16 of the crank pin 12, i.e. _{W / {0.5 × (D p} + D j) In FIG. 5 showing the relationship between｝ and the stress-vibration ratio, the solid line X in the figure indicates the R portion J _f of the connection portion between the crank journal 16 and the web portion 14.
Shows the stress 38628 huya ratio, the dotted line Y indicates the stress amplitude ratio of the R portion P _f of the connection portion between the crank pin 12 and the web portion 14.

As shown by the curves X and Y in the drawing, when the width W of the web portion 14 is relatively small with respect to the diameter of the crankpin 12 and the crank journal 16, the stress amplitude ratio is large, and thus the stress amplitude ratio is large. The effect of reducing the stress cannot be obtained, and the web portion 14 does not effectively contribute to the reduction of the stress in the R portion. When the width W of the web portion 14 becomes relatively large, the stress amplitude ratio rapidly decreases, the stress reduction effect increases, and the web portion 14 effectively contributes to the stress reduction of the R portion.

When the width W of the web portion 14 is relatively large and the value of W / {0.5 × (D _p + D _j )} exceeds 1.4, the degree of reduction of the stress amplitude ratio gradually increases. When the value becomes smaller and the value of W / {0.5 × (D _p + D _j )} reaches 1.6, the stress amplitude ratio becomes a substantially minimum value, and
Even if the value of {0.5 × (D _p + D _j )} becomes relatively large beyond 1.6, the stress amplitude ratio remains substantially constant, and the weight of the crankshaft 10 unnecessarily increases. However, the effect of further reducing the stress of the R portion cannot be obtained.

[0016] From the above results, R section _{J f, P f,} P _r and _J R portion is greater than the third cylinder which stress amplitude of _r corresponding to the other cylinders # 3 and web portion 14 of the fourth cylinder # 4 Width W
Is set to be larger than the width W of the corresponding web portion 14 of another cylinder, and the value of W / {0.5 × (D _p + D _j )} is set to 1.4.
In other cylinders, the web width W is relatively small, for example, W / ｛0.5 × (D
_By setting _p + D _j )｝ to be equal to or more than 1.1 and less than 1.4, there is an advantage that the strength of the crankshaft 10 as a whole can be substantially equalized and the weight can be reduced.

Next, as another means for effectively coping with the large stress amplitude occurring in each of the R portions of the crankshaft corresponding to the third cylinder # 3 and the fourth cylinder # 4, the first cylinder to the sixth cylinder are used. Crank pin 12 and web part 1 corresponding to each cylinder
4 and the crank journal 16 R unit _{J f, P f,} P _r
To all and J _r, then was subjected to induction hardening, the R portion is subjected to pressure processing by shot peening or rolling the further surface hardening treatment only on the R unit corresponding to the third cylinder and the fourth cylinder It is effective to perform additional surface hardening. By subjecting the R portion to shot peening or roll pressure processing to harden the surface, the fatigue strength is improved by 20 to 30%. Therefore, compared to the R portion corresponding to other cylinders that perform only induction hardening, the third portion is used. And the strength of the R portion can be increased by an amount substantially corresponding to the increase in the stress amplitude of the R portion corresponding to the fourth cylinder. Cost reduction can be achieved.

The crankshaft 10 may be a normal steel forged product or a spheroidal graphite cast product. The present invention also relates to a crankshaft of an inline 6-cylinder engine having an ignition sequence different from the above-mentioned ignition sequence, wherein an ignition interval is 360 degrees in crank angle and cylinders adjacent to each other exist. In this case, the crankpins 12 corresponding to these cylinders
The same applies to the width W of the web portion connected to the R, the R portion of the connection portion between the crank pin 12 and the web portion, and the R portion of the connection portion between the web portion and the crank journal. It is possible to obtain substantially the same effects and advantages as those described above.

[0019]

As described above, the crankshaft according to the present invention is the same as the crankshaft of the in-line type six-cylinder engine, but has the following characteristics.
The width of a web portion that ignites at a crank angle of 0 degree and connects a crankpin and a crank journal corresponding to two adjacent cylinders is changed to a web that connects a crankpin and a crank journal corresponding to another cylinder. After performing induction hardening on the connecting portion between the crank pin and the web portion and the R portion of the connecting portion between the web and the crank journal corresponding to the two cylinders, shot peening is performed. Or a roll press working, which is advantageous in that a crankshaft for an inline 6-cylinder engine, which is lightweight, has excellent strength, and has excellent durability and reliability, can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a side view of an entire crankshaft showing a preferred embodiment of the present invention.

FIG. 2 is a front view of a front end portion of the crankshaft shown in FIG.

FIG. 3 is an enlarged side view illustrating a crankshaft portion corresponding to a third cylinder of the crankshaft illustrated in FIG. 1;

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3;

FIG. 5 is a diagram showing a relationship between a width of a web portion and a stress amplitude ratio.

FIG. 6 is a diagram showing a stress amplitude at an R portion of a connection portion between a crank pin, a web portion, and a crank journal corresponding to a first cylinder to a sixth cylinder.

FIG. 7 is a diagram illustrating a stress generated in an R portion of a connection portion between a crank pin, a web portion, and a crank journal corresponding to a first cylinder, which is measured in relation to the ignition of the cylinders in self and other ignition orders. .

FIG. 8 is a diagram illustrating a stress generated in an R portion of a connection portion between a crankpin, a web portion, and a crank journal corresponding to a second cylinder, which is measured in relation to the ignition of the cylinders in self and other ignition orders. .

FIG. 9 is a diagram illustrating a stress generated in an R portion of a connection portion of a crank pin, a web portion, and a crank journal corresponding to a third cylinder, which is measured in relation to the ignition of the cylinders in self and other ignition orders. .

[Explanation of symbols]

Reference Signs List 10: crankshaft, 12: crankpin, 14: web part, 16: crank journal, 18: balance weight, _Pf and _Pr : Connection part R part between crankpin 12 and front and rear web parts 14, _Jf and _Jr : Connection portion R between the web portion 14 and the front and rear crank journals 16.

Claims (1)

[Claims] 1. In a crankshaft of an inline six-cylinder engine, a width of a web portion that ignites at a crank angle of 360 degrees and connects a crankpin and a crank journal corresponding to two adjacent cylinders is defined by: The width is set to be larger than the width of the web portion connecting the crankpin and the crank journal corresponding to the other cylinder, or the connection portion between the crankpin and the web portion corresponding to the two cylinders and the connection portion between the web and the crank journal A crankshaft characterized by subjecting an R part to induction hardening and then performing shot peening processing or roll pressure processing.