JP2000291624A - Crankshaft structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject structure capable of efficiently reducing its weight while having a ballanced torsional rigidity by forming a hollow hole for reducing the mass thereof that is provided to a crankpin in a shape for improving the balance of the rigidity through equalization of shearing stress generating in a crankshaft. SOLUTION: In a crankshaft structure formed with mass reducing hollow holes 10a, 10b extending toward the center of a crankpin 22 from a shoulder 34 of a crankarm 34 of a crankshaft 20, the holes 10a, 10b are formed in such a way that axes Xa, Xb of the holes 10a, 10b are inclined so that wall thicknesses on the sides A1, A2 where a maximum shearing stress τt generates when a maximum torsional torque TAmax acts may be thicker than wall thicknesses on the sides B3, B4 where a shearing stress τc generates when a minimum torsional torque TCmin acts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crankshaft structure of a crankshaft for an automobile engine or the like, which has a reduced weight.

More specifically, the present invention relates to a crankshaft structure having a reasonable shape of a lightening hole in consideration of torsional rigidity.

[0003]

2. Description of the Related Art In automobiles, there is a growing demand for improved fuel efficiency and an increased load capacity, as well as a demand for lighter engines, and this demand is increasing year by year. Therefore, a reduction in the weight of a crankshaft structure for changing the reciprocating motion of a piston into a rotary motion via a connecting rod is required and promoted.

As shown in FIGS. 6 and 7, the crankshaft structure includes a crank journal 31, a crank pin 32, a balance weight 33, a crank arm 34, an output flange portion.
35, which is composed of an accessory driving shaft portion 36 and the like, and is manufactured by heat treatment such as press die forging or forging of carbon steel or special steel and partial induction hardening as necessary.

On the opposite side of the crank pin 32, a balance weight 33 for balancing is provided on the crank arm 34 in a divided manner integrally formed or connected by bolts.
Balance at the time of 40 rotations.

Further, in order to supply the lubricating oil from the crank journal 31 via the oil hole 37b in order to lubricate between the crank pin 32 and the connecting rod, an oil hole is formed in the crank pin 32 from the crank arm 34. (Oil passage) 37a is drilled with a drill.

[0007] In order to reduce the weight of the crankshaft and to reduce the mass of the rotary motion part, a hollow for mass (mass) removal is provided in the crankpin for the crankshaft. .

In the crankshaft of the V-type engine, as shown in FIGS. 7 and 8, the hollow holes 11a and 11b for mass removal have shoulders 34a of the crank arm 34 inside the crank pin 42.
7, the axes Ya and Yb, which are also the processing axes, are viewed in plan, that is, the axis D of the crankpin 42 is aligned with the axis D of the crankshaft 31 as shown in FIG. When looking down from above at a position where the axis D and the axis C come on the same straight line coming above the axis C, a V-shape that is inclined with respect to the axis C of the crankshaft 40 is formed. Also in the side view shown in FIG.
The tip of b is formed in a V-shape toward the axis C of the crankshaft 40.

In the V-shape of the axes Ya and Yb in plan view, the machining shaft is provided along the oil hole 37a so as to avoid interference with the oil hole 37a penetrating the crank pin 42 provided before. It is.

[0010]

On the other hand, in an actual automobile engine, the torsional torque acting on the crankshaft is, as shown in FIG. 4, a periodic explosion represented by an average torque TAm as a driving torque. Dotted line T that changes depending on the load and the crank angle on the horizontal axis caused by resonance of the crankshaft system
A torque fluctuation (torsional vibration) as shown by B is accompanied, and a fluctuation torque as shown by a solid line TA obtained by adding them is obtained.

During normal operation, the average torque TAm is added to the fluctuation torque TB, so that the total torsional torque T
A is the absolute value of the maximum value TAmax on the + (plus) side,
Since the absolute value of the minimum value TAmin on the-(minus) side is larger than the absolute value, the maximum torsional stress occurs when the maximum value TAmax on the + side.

Therefore, as shown in FIG. 10, when the axes Za and Zb of the mass removal hollow holes 12a and 12b are provided on the axis D of the crankpin 52, the torsional torque TA is applied to the crankshaft 50. When operated, the shear stress generated in the crankpin 52 is such that the maximum shear stress (A1, A2) in the rotational direction torque is larger than the maximum shear stress (B3, B4) in the anti-rotation direction.

In particular, as shown in FIGS. 7 and 8, when the axes of the hollow holes 11a and 11b for mass removal are V-shaped in plan view,
That is, when the hollow holes 11a and 11b for mass removal indicated by the dotted lines shown in FIG. 9 are formed, the torsional torque TA acting on the crankshaft 40 causes one of the A1 and A2 sides on which TAmax acts to operate. B3 where the wall thickness becomes thin and TAmin acts
, The thickness of one B4 on the B4 side becomes thicker and at TAmax,
The shear stress is larger in the part A1 than in the part A2. Also, TAm
At the time of in, the shear stress becomes larger in the B3 portion than in the B4 portion. However, the torsional torque during normal operation is such that the maximum shear stress is A1 part> B3 part because the torque on the + amplitude side is larger than the torque on the-side.

Therefore, an unfavorable strength condition in which the wall thickness is small at the portion A1 and the thickness is large at the portion B4 where the generated shear stress is lower than the portion A1 where strength is required because the maximum shear stress is generated. Occurs. Therefore, when the weight reduction is promoted, there is a problem that the strength of the portion A1 in particular in FIG. 9 is insufficient, and the torsional rigidity is disadvantageous in strength.

In Japanese Utility Model Laid-Open Publication No. 56-12121, a hollow hole for mass removal is opened from a shoulder of a crank arm of a crankshaft, and oil is communicated from a tip of the hollow hole to a bearing oil hole of the crankshaft. There has been proposed a crankshaft structure in which a hole is cut and lubricating oil is smoothly supplied to a piston portion through the oil hole.

However, this Japanese Utility Model Application No. 56-1212
In the case of the crankshaft structure disclosed in Japanese Patent Application Publication No. 1 (1993), since this hollow hole for mass removal constitutes a part of the passage of each oil hole, a plug for closing is provided, and the hollow hole for mass removal is provided. The interior will be filled with lubricating oil. As a result, the inertia is increased by the mass of the lubricating oil and the plug compared to a complete hollow hole, and the mass increase on the crankpin side is accompanied by the mass increase of the balance weight. There is a problem that the effect of providing the hollow hole is small.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. It is an object of the present invention to provide a method for removing a mass from a hollow hole provided in a crankpin with respect to a torsional torque actually applied to the crankpin. The shape is such that the maximum shear stress on the part A side in the rotation direction and the part B on the anti-rotation direction side are equal to the hollow hole for use, that is, the shape is such that the rigidity is well balanced, and the torsional rigidity is balanced. It is an object of the present invention to provide a crankshaft structure that can reduce the weight efficiently.

[0018]

The crankshaft structure for achieving the above object is constituted as follows. 1) In a crankshaft structure in which a hollow for mass removal is formed from the shoulder of a crank arm of a crankshaft toward the center of the crankpin, the axis of the hollow for mass removal is defined by the axis of the crankpin in plan view. On the other hand, when the maximum torsional torque is applied during normal operation of the engine, the thickness on the side where the maximum shear stress is generated is the side where the shear stress is generated when the minimum torsional torque is applied, that is, The hollow hole for mass removal is formed by inclining so as to be thicker than the thickness of the side facing the hollow hole for mass removal.

The plan view means a position where the axis D of the crank pin 22 is located above the axis C of the crankshaft 20 and the axis D and the axis C are on the same straight line, as shown in FIG. The maximum torsion torque means the torsion torque at which the absolute value is maximized, and the torsion torque corresponding to TAmax in FIG. Torque.

According to this configuration, the thickness of the portion B where the shear stress is relatively small is small, and the thickness of the portion A on the side where the maximum shear stress is generated is large. The difference in stress is reduced.

2) Furthermore, the axes of the two mass extraction hollow holes drilled from shoulder portions of the crank arms on both sides of the crank pin are arranged in the same plane, and the mass extraction hollow holes are formed. By providing the same, the machining axis and the axis of the hollow hole for mass removal have the same inclination angle, and the set angle of the tool at the time of drilling remains fixed, so that machining workability is improved.

3) The difference between the absolute value of the maximum peak and the absolute value of the minimum peak of the torsional torque expected to be applied to the crankshaft is enlarged, and the plan view of the hollow hole for mass removal is viewed in plan view. The mass hole is provided with the hollow hole for mass removal by enlarging the angle of inclination of the axis with respect to the axis of the crankpin.

With this configuration, when the difference between the absolute value of the maximum peak TAmax and the absolute value of the minimum peak TAmin of the torsional torque TA shown in FIG. 4 is enlarged, A1 at the maximum peak in FIG.
Since the difference between the magnitude of the maximum shear stress generated at the part and the magnitude of the maximum shear stress generated at the B4 part at the time of the minimum peak increases, the balance of rigidity is further improved by setting a larger inclination angle, Regarding the substantial strength, the maximum shear stress at each of the A and B portions becomes substantially the same with respect to the torque actually applied to the crankpin. Can demonstrate.

As a case where such a minimum torsional torque becomes a problem, it is considered that an exhaust brake is used in an automobile engine. In addition, the crankshaft of other equipment depends on the usage.

Specific examples of the crankshaft include a crankshaft of an internal combustion engine and a crankshaft of an air compressor. Any crankshaft that receives torque and is required to be reduced in weight may be used. In particular, the invention is not limited to the crankshaft. Also, the presence or absence of the oil hole does not matter.

Therefore, the rigidity and strength are balanced with respect to the torque actually applied to the crank. That is, it is possible to provide the crank pin with the hollow hole for removing the mass while preventing the rigidity and the strength of the crankshaft against torsion from being unbalanced. Therefore, since a larger hollow hole for mass removal can be provided, the weight of the crankshaft can be reduced.

Since the value of the maximum shear stress of the double vibration generated by the torsional torque also depends on the thickness of the crank pin around the hollow hole for mass removal, this inclination angle is determined by the following equation. It changes depending on the size of the diameter of the hollow hole for mass removal with respect to the diameter and the like.

For this reason, it is possible to determine the value by performing an experiment for measuring the stress generated by the torsional torque of the crankshaft of various shapes.
By analytical numerical calculation methods such as EM (finite element method),
With the diameters da, db and the inclination angles αa, αb of the hollow holes 10a, 10b shown in FIG. 3 being changed, the torsional stress generated in the crankshaft 20 is simulated and calculated. Based on the hollow hole 10 for mass removal
The diameters da and db and the inclination angles αa and αb of a and 10b can be determined.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. The crankshaft in the crankshaft structure according to the embodiment of the present invention has a journal 31, a crankpin 32, a balance weight 33, an arm 34, an output flange 35, an auxiliary machine, similarly to the crankshaft 30 shown in FIGS. The auxiliary drive shaft 36 is provided with a crank pulley (not shown). In addition, an oil hole 37, a mounting hole 39, and the like are formed, and a split balance weight (not shown) is mounted on the balance weight mounting portion 44 having the female screw portion 43.

As shown in FIGS. 1 to 3, the crankshaft 20 is provided with hollow holes 10a and 10b for mass removal. The hollow holes 10a and 10b are provided from the shoulder 34a of the crank arm 34 of the crankshaft 20 toward the center of the crank pin 22.
1 and 3, the maximum torsional torque TAmax as shown in FIG. 4 with respect to the axis D of the crankpin 22 in plan view as shown in FIGS. When actuated, the thickness of A1 and A2 of the crank of FIG.
The hollow holes 10a and 10b are formed so as to be inclined so as to be thicker than the thicknesses of the sides B3 and B4 where the pits occur.

According to the crankshaft structure having the above-described structure, when the hollow holes 10a and 10b for mass removal are provided in the crankshaft 20 of an engine or the like, the hollow holes 10a and 10b for mass removal are set by the maximum torsional torque TAmax. The portions A1 and A2 where the peripheral shear stress τt is generated are thickened, and the shear stress τc due to TAmin is used.
Since the portions B3 and B4 where the cracks occur can be formed thin, the mass reduction hollow holes 10a and 10b are provided to reduce the weight of the crankshaft 20 while maintaining the rigidity and strength of the crankshaft 20 in a well-balanced manner. be able to.

Further, holes 2 are formed from shoulder portions 34a of the crank arm 34 on both sides of the crank pin 22, respectively.
The axes Xa, Xb of the three hollow holes 10a, 10b are arranged in the same plane, and the hollow holes 10a, 10b are provided. That is, the inclination angle αa is equal to αb, and the axes Xa and Xb are formed so as to be straight in the plan view of FIGS. 1 and 3.

With this configuration, the hollow holes 10a,
Since the axes Xa and Xb of 10b are the same as the machining axes at the time of drilling, the machining axes X of both the hollow holes 10a and 10b for mass removal are used.
Since the inclination angles of a and Xb are the same, the set angle of the tool at the time of drilling can be kept fixed, and workability at the time of drilling can be improved.

Next, the average torque T applied to the crankshaft 20
The variation range of m is between TBm and TAm shown in FIG.
The setting of the inclination angles αa and αb when TAm is larger than TBm and the absolute value of the maximum peak TAmax is significantly larger than the absolute value of the minimum peak TBmin will be described.

The inclination angles αa and αb are different from the torsional torque T as shown in FIG.
The difference between the absolute value of the maximum peak TAmax and the absolute value of the minimum peak TBmin (| TAmax | − | TBmin |) and the inclination angles αa and αb in a plan view are expanded, and the hollow holes 10a, 10b is provided.

With this configuration, when the difference between the absolute value of the maximum peak TAmax and the absolute value of the minimum peak TBmin of the torsional torque T shown in FIG. 4 is enlarged, the maximum tensile stress generated at the portion A1 at the time of the maximum peak TAmax is obtained. The magnitude of σtmax1 and the maximum tensile stress σtmax generated at B4 at the minimum peak TBmin
Since the difference from the size of 4 increases, the balance of rigidity can be further improved by increasing the inclination angles αa and αb.

Next, the average torque T applied to the crankshaft 20
As shown in FIG. 5, the variation range of m
And fluctuates between TAm and TCm, that is, when the absolute value of TAm is larger than the absolute value of TCm,
The setting of the inclination angles αa and αb in a case where the absolute value of the maximum peak TAmax is larger than the absolute value of the minimum peak TCmin but the minimum peak TCmin cannot be ignored will be described.

When the engine brake is applied, as shown in FIG. 5, the average torque TCm is applied to the minus side in the direction opposite to that in the normal operation, so that the overall torque shifts to the minus side, as indicated by the line TC. However, the absolute value of the average torque TCm during engine braking is the average torque TAm during normal operation.
Therefore, the absolute value of the minimum peak TCmin when the engine brake is used becomes smaller than the maximum peak TAmax of the fluctuation torque. However, when the absolute value of the minimum torsional torque TCmin becomes large, the inclination angles αa and αb are set in consideration of the maximum shear stress τtmaxC generated when the minimum torsional torque TCmin acts. It is necessary to provide hollow holes 10a and 10b for mass removal.

[0039]

As described above, according to the crankshaft structure of the present invention, the axis of the hollow hole for mass removal for weight reduction formed on the crankpin of the crankshaft of the engine, that is, the machining axis, is Considering the torque actually applied to the crankpin with respect to the axis of the crankpin visually, by forming it at an angle, the balance between the stress and strength generated on the crankshaft is improved, and the overall rigidity strength Therefore, the crankpin can be provided with a hollow for mass removal without reducing the torsional rigidity of the crankshaft. Accordingly, since a larger hollow hole for mass removal can be provided, the weight of the crankshaft can be reduced.

If the axes of the hollow holes for mass removal provided on both sides of the crankpin are arranged in the same plane, the machining axes of both the hollow holes for mass removal have the same inclination angle. The set angle of the work can be fixed,
Since there is no need to change the set of tools, workability during machining can be improved.

Further, according to the magnitude of the maximum torsional torque and the minimum torsional torque expected to be applied to the crankshaft,
By setting the inclination angle between the axis of the crankpin and the axis of the mass removal hollow hole in plan view and providing the mass removal hollow hole, the thickness of the surrounding part of the mass removal hollow hole is changed, and the rigidity is changed. Since it is possible to further improve the balance in terms of strength and strength, it is possible to provide a lightweight crankshaft structure having well-balanced rigidity and strength and excellent durability.

[Brief description of the drawings]

FIG. 1 is a partial plan view of a crankshaft showing a state of a hollow for mass removal of a crankshaft structure according to the present invention.

FIG. 2 is a partial side view of the crankshaft of FIG.

FIG. 3 is a partial plan view of a crankpin portion of the crankshaft of FIG. 1;

FIG. 4 is a schematic diagram for explaining a time variation of a torsional torque of a crankshaft system.

FIG. 5 is a schematic diagram for explaining a time variation of a torsional torque of a crankshaft system to which a negative side operating torque is also applied.

FIG. 6 is a diagram illustrating an example of a crankshaft.

FIG. 7 is a partial view of a crankshaft showing a state of a hollow for mass removal of a prior art crankshaft structure.

FIG. 8 is a partial side view of the crankshaft of FIG. 7;

FIG. 9 is a partial plan view of a crankpin portion of the crankshaft of FIG. 7;

FIG. 10 is a partial plan view of a crankpin portion for explaining a torsional stress distribution of a crankpin having a crankshaft structure without a hollow for mass removal.

[Explanation of symbols]

 10a, 10b, 11a, 11b Hollow hole for mass removal 20, 30, 40, 50 Crankshaft 22, 32, 42, 52 Crank pin 31 Crank journal 33 Balance weight 34 Crank arm 34a Shoulder 37a, 37b Oil hole A1, A2 Part with large torsional stress B3, B4 Part with small torsional stress C Axis of crankshaft D Axis of crankpin T, TA, TB, TC Torsion torque Xa, Xb Axis of hollow hole for mass removal (machining) Shaft) Ya, Yb Axis of hollow hole for mass removal (machining axis) Za, Zb Axis of hollow hole for mass removal (machining axis)

Claims (3)

[Claims] 1. A crankshaft structure in which a hollow for mass removal is formed from a shoulder portion of a crank arm of a crankshaft toward a center side of the crankpin, wherein an axis of the hollow for mass removal is defined by a crank in plan view. When the maximum torsional torque acts on the axis of the pin during normal engine operation, the thickness at the side where the maximum shear stress occurs is the side at which the shear stress occurs when the minimum torsional torque acts, That is, a crankshaft structure characterized in that the hollow hole for mass removal is formed so as to be inclined so as to be thicker than the wall facing the hollow hole for mass removal. 2. The mass removal hollow holes are provided by arranging the axes of two mass removal hollow holes drilled from shoulder portions of crank arms on both sides of the crank pin in the same plane. The crankshaft structure according to claim 1, wherein: 3. The enlargement of the difference between the absolute value of the maximum peak and the absolute value of the minimum peak of the torsional torque predicted to be applied to the crankshaft, and the axis of the mass removal hollow hole in a plan view. 3. The crankshaft structure according to claim 1, wherein the hollow hole for mass removal is provided by enlarging an angle of inclination with respect to an axis of the crankpin.