JP3670124B2 - Crankshaft structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure of a crankshaft used for a vehicle engine or the like, and intends to achieve both reduction in weight and securing strength for improving reliability.
[0002]
[Prior art]
Along with higher output and higher rotation of a vehicle engine, the crankshaft, which is a main motion system component of the engine, is required to be lighter and more lightweight, and the shape must be optimized. Conventionally, in order to optimize the shape of the crankshaft, as shown in Japanese Patent Laid-Open No. 9-25925, a crank pin and a crank journal are continuously connected by a crank web, and a lightening portion is provided on the crank web. A formed crankshaft has been proposed. In the conventional crankshaft, the stress resistance of the fillet R portion is improved by the crank web, and the weight is reduced by the thinned portion.
[0003]
[Problems to be solved by the invention]
However, in the conventional crankshaft, the optimal width of the crank web and the optimum shape of the thinned portion are not specified with respect to the crankpin diameter and the crank journal diameter. It could not be said.
[0004]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a crankshaft structure capable of achieving both weight reduction and ensuring strength for improving reliability.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to a first aspect of the present invention , a crank web is extended from a shaft end of a crank pin in a direction orthogonal to the axis, and a crank journal extending along the axis of the crank pin is provided on the crank web. In the crankshaft connected to the outside, the crankshaft is a crankshaft corresponding to a multi-cylinder engine, and the maximum width W of the crank web corresponding to at least one cylinder other than both ends in the axial direction of the crankshaft. , A relational expression among the maximum width W of the crank web, the diameter D _{p of the} crank pin, and the diameter D _{j of the} crank journal
W / {0.5 · (D _p + D _j )} is set to 1.4 to 1.6,
The maximum width W of the crank web corresponding to the cylinders at both ends is expressed by a relational expression.
W / {0.5 · (D _p + D _j )} is set to be less than 1.4.
[0006]
And the stress reduction effect of the part where the stress of the fillet R part of the crankshaft applied to a plurality of cylinders is large is aimed at, the weight is reduced without deteriorating the stress reduction effect in the part where the stress of the fillet R part is relatively small, To further reduce the weight of the crankshaft.
[0007]
Further, the crank pin and the crank journal are connected by a crank web, and a hole is formed in the crank web toward the crank pin. The relationship between the hole diameter d and the crank pin diameter Dp is 0.3 / dp = 0.3. The weight of the crankshaft is reduced without lowering the bending rigidity and torsional rigidity.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a side view of a main part showing a crankshaft structure according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1, and FIG. The characteristics are shown.
[0009]
As shown in FIGS. 1 and 2, the crankshaft 1 is provided with a crankpin 2, and a crank web 3 is extended at a shaft end of the crankpin 2 in a direction perpendicular to the axis. A crank journal 4 extending along the axis of the crankpin 2 is connected to the outside of each crank web 3. Since the crank web 3 is provided, the stress on the fillet R portions 5a and 5b is particularly reduced.
[0010]
Relationship between the diameter D _j of the crank diameter of the width W and the crank pin 2 of the web 3 D _p and the crank journal 4 has a diameter of (crank width W of the web 3) / (diameter of the crank pin 2 D _p and the crank journal 4 D _j average), that is, W / {0.5 · (D _p + D _j )} is set to 1.4 to 1.6.
[0011]
The reason why the dimensions of each part of the crankshaft 1 are set as described above will be described with reference to FIG. FIG. 3 is a graph showing the relationship between the stress amplitude ratio and [W / {0.5 · (D _p + D _j )}]. How the width W of the crank web 3 affects the stress amplitude ratio. Is shown. The solid line in the figure shows the stress amplitude ratio of the fillet R portion 5b on the crank journal 4 side, and the dotted line in the figure shows the stress amplitude ratio of the fillet R portion 5a on the crankpin 2 side.
[0012]
As shown in FIG. 3, when the width W of the crank web 3 is relatively small, that is, when the value of [W / {0.5 · (D _p + D _j )}] is small, the stress amplitude ratio is large. The reduction effect is not obtained, and the crank web 3 does not contribute to the stress reduction effectively. When the width W of the crank web 3 is relatively increased, that is, when the value of [W / {0.5 · (D _p + D _j )}] is increased, the stress amplitude ratio is reduced and a stress reduction effect is obtained. As a result, the crank web 3 effectively contributes to stress reduction.
[0013]
When the width W of the crank web 3 is relatively increased so that the value of [W / {0.5 · (D _p + D _j )}] is 1.4, the degree of decrease in the stress amplitude ratio is small. Thus, when the value of [W / {0.5 · (D _p + D _j )}] is 1.6 or more, the stress amplitude ratio becomes substantially constant. For this reason, the width W of the crank web 3, the diameter D _p of the crank pin 2 and the diameter of the crank journal 4 are set so that the value of [W / {0.5 · (D _p + D _j )}] is 1.4 or more. By setting D _j , the stress amplitude ratio is reduced and a stress reduction effect can be obtained.
[0014]
On the other hand, when the value of [W / {0.5 · (D _p + D _j )}] is 1.6 or more, the stress amplitude ratio becomes substantially constant, and the width W of the crank web 3 is relatively increased. Even if the value of [W / {0.5 · (D _p + D _j )}] is larger than 1.6, the stress reduction effect does not change. For this reason, even if the value of [W / {0.5 · (D _p + D _j )}] is larger than 1.6, only the weight of the crankshaft 1 is increased and a further stress reduction effect cannot be obtained.
[0015]
Therefore, with respect to the diameter D _p of the crank pin 2 and the diameter D _{j of the} crank journal 4 so that the value of [W / {0.5 · (D _p + D _j )}] is 1.4 to 1.6. By setting the width W of the crank web 3, a maximum stress reduction effect can be obtained with a minimum weight increase. That is, without increasing the weight of the crankshaft 1 by increasing the width W of the crank web 3 more than necessary, the stress reduction effect of the fillet R portions 5a and 5b is appropriately maintained, and the crankshaft 1 is reduced in weight. be able to. For this reason, it is possible to achieve both strength ensuring and weight reduction for improving reliability.
[0016]
Width W of the crank webs 3 for all diameters of the crank pin 2 D _p and the diameter D _j of the crank journal 4 in the crank shaft 1, the above-described [W / {0.5 · (D p + D j)}] It is possible to set the value of 1.4 to 1.6, but in an actual engine, the situation of the bending stress that the crankshaft 1 receives depending on the part of the cylinder varies.
[0017]
FIG. 4 shows the state of stress amplitude of each crankpin 2 of the crankshaft 1 and fillet R portions 5a and 5b of the crank journal 4 in a four-cylinder engine. Maximum stress position of the crank pin 2 is a rear P _R of the front P _F and No3 cylinder of No2 cylinder. The maximum stress position of the crank journal 4 is a rear J _R of the front J _F and No3 cylinder of No2 cylinder.
[0018]
The fillet R portions 5a and 5b of each crankpin 2 and crank journal 4 are affected by vibrations caused by explosion of adjacent cylinders. For this reason, the parts corresponding to the No. 2 cylinder and No. 3 cylinder with the crank pin 2 and the crank journal 4 adjacent to each other are the No. 1 cylinder and No. 4 cylinder which are the cylinders at both ends where the crank pin 2 and the crank journal 4 are not adjacent to each other only. The stress is larger than the corresponding part.
[0019]
Therefore, in the case of the crankshaft 1 in a four-cylinder engine, the width W of the crank web 3 corresponding to the No. 2 cylinder and the No. 3 cylinder (or either one) is set to [W / {0.5 · (D _p + D _j )}. ] Is set to 1.4 to 1.6, and the width W of the crank web 3 corresponding to the No. 1 cylinder and No. 4 cylinder is set to [W / {0.5 · (D _p + D _j )}]. Is set to be less than 1.4.
[0020]
By doing in this way, the stress reduction effect of the part where the stress of the fillet R part 5 of the crankshaft 1 applied to the four-cylinder engine is large can be achieved, and the stress reduction effect is provided at the part where the stress of the fillet R part 5 is relatively small. The weight can be reduced without deteriorating, and the crankshaft 1 can be further reduced in weight.
[0021]
Next, a second embodiment of the present invention will be described with reference to FIGS. Side of the main part representing the crank shaft structure according to the second embodiment, in FIG. 6 is shows the analysis conditions of the stiffness and mass to the diameter D _p of diameter d / crank pin hole of the present invention in FIG. 5 . Since the structure of the crankshaft is the same as that shown in FIG. 1, the same reference numerals are assigned to the same members.
[0022]
In the illustrated crankshaft 1, a crankpin 2 and a crank journal 4 are connected by a crank web 3, and a hole 6 is formed in the crank web 3 toward the crankpin 2. By forming the hole 6, the weight is reduced by removing the meat. When reducing the weight of the crankshaft 1 by removing the thickness or the like, an increase in bearing impact force due to a decrease in bending rigidity may increase crankcase vibration and increase engine noise.
[0023]
In order to enable weight reduction by suppressing a reduction in bending rigidity, the diameter d of the diameter D _p and the hole 6 of the crank pin 2, which is the relationship d / D _p is 0.3 or less. This relationship, bending is for weight reduction without reducing the rigidity and torsional rigidity, the d / D _p exceeds 0.3, thereby the weight of the crank shaft 1 lightening too many The rigidity of things will decrease. The reason why the weight can be reduced by suppressing the decrease in bending rigidity when d / _Dp is 0.3 or less will be described with reference to FIG.
[0024]
FIG. 6 shows bending rigidity for d / D _p, a graph showing the torsional stiffness and mass relationship, d / D _p is the bending stiffness, how to influence the torsional stiffness and mass. Solid line in the figure represents the ratio of the bending rigidity with respect to d / D _p, dotted line in the figure indicates the ratio of torsional rigidity for the d / D _p, a one-dot chain line in the drawing are shown the mass of ratio d / D _p.
[0025]
As can be seen, according to increasing the diameter d of the hole 6 (in accordance with increasing the d / D _p), reduced bending stiffness and torsional stiffness are both particularly bending stiffness, d / D _p is 0. When it exceeds 15, it begins to decrease, and when it exceeds 0.3, it decreases rapidly. Further, as the diameter d of the hole 6 is increased, the mass is reduced and the weight can be reduced. In other words, it can be seen that it is optimal that d / _Dp is 0.3 or less in order to achieve both weight reduction and securing of rigidity. In particular, when d / D _{p is set} to 0.15 or less, weight can be reduced with almost no reduction in rigidity, and when d / D _{p is set} to 0.3 or less, weight can be reduced with a practical reduction in rigidity. .
[0026]
Therefore, the crankshaft 1 described above can reduce the weight of the crankshaft 1 without reducing bending rigidity and torsional rigidity by setting d / _Dp to 0.3 or less. For this reason, it is possible to achieve both the securing of strength for improving reliability and weight reduction.
Further, in the crankshaft in which the crankpin and the crank journal are connected by the crank web, the relationship between the crank web width W, the crankpin diameter _Dp, and the crank journal diameter Dj is _expressed as W / {0.5 · Since (D _p + D _j )} is set to 1.4 to 1.6, the stress reduction effect of the fillet R portion can be reduced without causing an increase in weight due to an unnecessarily increased width of the crank web. The crankshaft can be made lighter by keeping it appropriate. As a result, it is possible to achieve both strength ensuring and weight reduction for improving reliability.
[0027]
【The invention's effect】
According to a first aspect of the present invention, a crankshaft is formed by extending a crank web in a direction perpendicular to the axis from the shaft end of the crankpin, and connecting a crank journal extending along the axis of the crankpin to the outside of the crankweb. The crankshaft is a crankshaft corresponding to a multi-cylinder engine, and has a maximum width W of the crank web corresponding to at least one cylinder other than both ends of the crankshaft in the axial direction. The relational expression W / {0.5 · (D _p + D _j )} between the large W, the crank pin diameter D _p and the crank journal diameter D _j is set to 1.4 to 1.6. ,
The maximum width W of the crank web corresponding to the cylinders at both ends is expressed by a relational expression.
Since W / {0.5 · (D _p + D _j )} is set to be less than 1.4 ,
Crankshaft applied to a plurality of cylinders is designed to reduce the stress at a portion where the stress of the fillet R portion of the crankshaft is large, and to reduce the weight without deteriorating the stress reduction effect at a portion where the stress of the fillet R portion is relatively small. Can be further reduced in weight. As a result, it is possible to achieve both strength securing and weight reduction for improving reliability at a high level.
[0028]
Further, the crank pin and the crank journal are connected by a crank web, and a hole is formed in the crank web toward the crank pin. The relationship between the hole diameter d and the crank pin diameter Dp is 0.3 / dp = 0.3. Since it is set to be as follows, the weight of the crankshaft is reduced without lowering the bending rigidity and torsional rigidity. As a result, it is possible to achieve both strength ensuring and weight reduction for improving reliability.
[Brief description of the drawings]
FIG. 1 is a side view of a main part showing a crankshaft structure according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line II-II in FIG.
FIG. 3 is a graph showing stress characteristics with respect to web width of a crankshaft structure.
FIG. 4 is a graph showing the state of stress amplitude of the crankshaft 1 of a four-cylinder engine.
FIG. 5 is a side view of a main part showing a crankshaft structure according to a second embodiment of the present invention.
FIG. 6 is a graph showing the relationship between hole diameter d / crank pin diameter _Dp , rigidity, and mass.
[Explanation of symbols]
1 Crankshaft 2 Crankpin 3 Crank web 4 Crank journal
5a, 5b Fillet R section 6 Hole D _j Crank journal 4 diameter D _p Crank pin 2 diameter d Hole 6 diameter

Claims (1)

In a crankshaft in which a crank web is extended from a shaft end of the crankpin in a direction orthogonal to the axis, and a crank journal extending along the axis of the crankpin is connected to the outside of the crank web.
The crankshaft is a crankshaft corresponding to a multi-cylinder engine,
The maximum width W of the crank web corresponding to at least one cylinder other than both ends in the axial direction of the crankshaft is a relational expression between the maximum width W of the crank web, the diameter Dp of the crank pin, and the diameter Dj of the crank journal. W / {0.5 · (Dp + Dj)} is set to 1.4 to 1.6,
A crankshaft structure in which the maximum width W of the crank web corresponding to the cylinders at both ends is set so that the relational expression W / {0.5 · (Dp + Dj)} is less than 1.4.

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