JP3062094B2 - Crankshaft - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a crankshaft of a multi-cylinder internal combustion engine having a plurality of arm portions and a shaft portion.

[0002]

2. Description of the Related Art In a two-stroke marine diesel engine, for example, in order to reduce the torsional vibration stress generated on the crankshaft, the torsional vibration resonance rotational speed must be increased as much as possible above the engine operating rotational speed. There is. For this reason, conventionally, the moment of inertia of a haze car has been reduced,
Methods such as thickening the flange and shortening the shaft length to increase the torsional rigidity of the shaft system have been used.However, these methods have limitations due to structural and performance limitations. In some cases, the resonance speed cannot be increased to a target value.

[0003] It is to be noted that a lean is provided on the crank arm, and the dynamic balance of the crank shaft is corrected by adjusting the amount thereof.
A crankshaft that reduces vibration has been proposed (see Japanese Utility Model Laid-Open No. 3-114620). However, in such a method, the weight of the crankshaft increases due to the waste, and the resonance rotational speed decreases.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, and can easily increase the resonance speed of torsional vibration, improve dynamic balance and reduce weight. It is an object to provide a crankshaft.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to the first aspect of the present invention, wherein the dimensions are width and thickness.
Wherein A comprise a plurality of arm portions and a shaft portion having an
The end of the arm portion on the shaft portion side is a semicircle having the same diameter as the width.
In a crankshaft for a large multi-cylinder marine internal combustion engine equipped with a propeller, the plurality of arm portions having the width and the thickness.
Of the torsional torque of the shaft part obtained by the torsional vibration calculation, the maximum width and thickness capable of transmitting the maximum torque
Maximum der of the dimensions comprises a certain maximum width and maximum thickness
And those with a maximum dimension, said at least one of said width or said thickness is not smaller than the maximum width or the maximum thickness in a range capable of transmitting a torsional torque of the shaft portion maximum dimension that One having a reduced dimension that is a reduced dimension.

According to a second aspect of the present invention, in addition to the above, the plurality of arm portions have a maximum dimension having a maximum width and a maximum thickness capable of transmitting a maximum torque, and the arm portion has a maximum width within a range capable of transmitting a torque. A width having a reduced width smaller than the width.

According to a third aspect of the present invention, in addition to the features of the first aspect, the arm portion and the shaft portion are formed by being assembled.

[0008]

1 and 2 show examples of crank throws of a crankshaft to which the present invention is applied, and FIG. 3 shows an example of the entire structure of a crankshaft having these crank throws. Crankshaft of the present embodiment, NO1 cylinder portion to NO10 cylinder portion of the crank arm 1a as a plurality of arm portions, 1b~10a, propeller comprises a 10b
1 is a crankshaft for a large marine two-stroke diesel engine as an example of a large marine large multi-cylinder internal combustion engine to be equipped .
This diesel engine has 10 cylinders 800 mm in diameter.
Equipped with cylinder, continuous maximum output and rotation speed are 34300KW × 9
3 RPM.

The crankshaft of this embodiment is of an assembling type,
Each of the crank arms 1a, 1b to 10a to 10b
The crankshaft portions 11 to 21 as the respective shaft portions have a correspondence relationship shown in FIG. 3, and both ends or one end of each crankshaft portion is shrink-fitted into the hole h of the crank arm shown in FIGS. The two are connected so that torque can be transmitted. The crankshaft portion 16 is divided into 16a and 16b, and is bolted at a flange portion. A camshaft drive chain wheel 22 is mounted between them. Reference numeral 23 denotes a thrust collar portion for a thrust bearing, reference numeral 24 denotes a turning gear / flap wheel mounting flange portion, and reference numeral 25 denotes a flange portion for connecting a stern shaft system to which a propeller is mounted. Crankshaft 11 to 16
a, 16b to 21 are rotatably supported by main bearings.

The crank arms 1a, 1b to 10a, 10
b has a maximum dimension with a maximum width and a maximum thickness capable of transmitting the maximum torque. In this example, the crank arms 7a and 7b shown in FIG. 2 have the same maximum width and maximum thickness.
9a, 9b, and as having a reduced dimension in which at least one of the width or the thickness is smaller than the maximum width or the maximum thickness in a range in which the torque can be transmitted, the width is reduced in the present example. It comprises crank arms 1a, 1b to 6a, 6b and 10a, 10b shown in FIG. 1 having a reduced width. In FIG. 1, the shape of the crank arm having a large width in FIG. 2 is indicated by a two-dot chain line for comparison.

The crank arms 1a and 1b are integrally forged together with the crank pin 1c to form a crank throw 1. Similarly, the other crank arms have crank throws 1 to 10 corresponding to cylinders NO 1 to NO 10 as shown in FIG. 3 by a pair of crank arms a and b and a crank pin c. Although not shown, an explosion force in the cylinder is transmitted to the crank pin 1c through a piston, a connecting rod, or the like, and the force is converted into output torque of the crankshaft portions 11 and 12 through the crank throw 1, Rotate a propeller or the like that becomes a load.

Due to this torque, a shear stress is generated in the shrink-fit portion between the crank arm and the crankshaft portion. However, a frictional force corresponding to the shear stress is generated by the surface pressure between the two due to the shrink fitting, and the gap between the two. Torque is transmitted without slippage.
For this purpose, the surface pressure of the transmission surface corresponding to the magnitude of the transmission torque is required, and the width and thickness of the eyeglass portion of the crank arm are reduced so that the stress generated by this surface pressure is suppressed to a predetermined value or less. Must be determined. The width W, W 'or w, w' and thickness T of the crank arm shown in FIGS. 1 and 2 are determined so as to be larger than required dimensions corresponding to the transmission torque as described above.

FIG. 4 shows the state of the torsional torque of the shaft portion of the crankshaft obtained by the torsional vibration calculation based on the program recognized by the International Classification Society (IACS). The shaft torque is a value obtained by adding the output torque and the additional torque due to the torsional vibration. The reference numeral at the right end in the figure is the same as the reference numeral of the crankshaft in FIG. 3, and indicates the calculated torque position.

As shown in the figure, the shaft torque greatly differs depending on the position of the cylinder. In the range of the output and the rotation speed below the continuous maximum output, NO7 to NO at the points A and B
Shaft torques associated with crank throws 7-9 corresponding to nine cylinders are a maximum torque of about 5600 (KNm) and a second torque of about 5400 (KNm). On the other hand, the crank throws 9 and 1 at the point C which becomes an intermediate torque.
0 is about 4800 (KNm), which is about 86% of the maximum torque. The shaft torque related to the crank throws 1 and 2 at the point D has a minimum torque of about 3000 (KNm).
Nm), which is about 54% of the maximum torque.

According to the above calculation results, in the crankshaft of the present embodiment, as described above, the crank throws 1 to 6 and 10 related to the small shaft torque have W
For crank throws 7 to 9 relating to a large shaft torque, a crank arm having a maximum width of W 'and w' larger than W and w as shown in FIG. The torsion torque of the corresponding crankshaft can be transmitted to any of the crank arms.

FIGS. 1 to 3 show examples in which the width of the crank arm is reduced. When the width is reduced, the length of the crankshaft does not change, and it is not necessary to change the configuration of the entire engine. Therefore, the application of the present invention is extremely easy. By applying the design, the thickness T can be reduced instead of or with the width.

When the thickness is changed, the stress of the fillet portion f of the crank arm shown in FIG. For this stress, the maximum pressure in the cylinder and the torsional torque of the shaft part are almost equally affected, and the stress and the thickness are almost squared (the stress is inversely proportional to the square of the thickness. Changes), the amount by which the thickness can be reduced by reducing the torsional torque is not as noticeable as the width.
However, for example, as described above, the minimum torque 3000 (KN
When m) is about 54% of the maximum torque of 5600 (KNm), the stress in the fillet becomes about 77%, and the thickness T can be reduced to about 12% if the allowable stress is the same. It is. And, by such a reduction in thickness, a weight reduction effect and a torsional vibration resonance rotation speed increasing effect can be obtained.

Conventionally, only the maximum value of 5600 (KNm), which is the maximum value of the normal shaft portion torque, is calculated, and the width and the thickness of the crank throw of all the cylinders are set to the size shown in FIG. The torsion torque at each position of the crankshaft is calculated, and the present invention is applied by using the calculated torsional torque. For example, three cylinders are reduced to the size shown in FIG. 2 and the remaining seven cylinders are reduced to the size shown in FIG. By doing so, the total weight was reduced by about 14 tons (about 10% based on the total weight of the crank throws 1 to 10). In addition, the rotational inertia mass is reduced, and the resonance rotational frequency of the torsional vibration is reduced to about 2RP.
By increasing the engine speed by M, the dangerous rotation speed could be driven up to a rotation speed sufficiently higher than 93 RPM which is the rotation speed at the time of continuous maximum output. As a result, the torsional vibration stress at the time of continuous maximum output and in the range of the predetermined overspeed rotation speed could be reduced to a safe range. The dynamic balance of the engine has also been improved. In addition, the reduction in crankshaft weight has reduced the manufacturing cost of the crankshaft. Further, the weight of the engine as a whole is reduced, and when the engine is mounted on a ship, the light weight, which is the weight of the ship, is reduced, and the effect of increasing the payload is accordingly achieved.

In the above example, the crank arms having the same width are used for one crank throw in consideration of the commonality of parts, the balance of the engine, and the like. Since almost no torque is applied to the arm 1a, and the torque applied to the crank arms 7a and 7b is significantly different in the crank throw 7, the transmission torque is different between the crank arms on both sides. It is also possible to reduce the weight of the crank arm by changing the width of the crank arm. Further, in the above description, the crank throw has been unified into two types of crank throws having two types of crank arm widths based on the magnitude of the shaft torque, but the crank arm width is finely changed for each magnitude of the corresponding shaft torque to further increase the weight. You may make it reduce and raise a resonance rotation speed.

The case where the crankshaft is of the assembled type has been described above. In this case, since the crank arm has a width w ′ (see FIG. 2) necessary for shrink fitting around the hole for shrink fitting, the crank arm has to have an optimum size corresponding to the shaft torque. Accordingly, the weight of the crank arm can be reduced extremely easily and effectively, and the torsional vibration resonance rotation speed can be increased. However, even with an integral crankshaft that can be integrally forged, the magnitude of the shaft torque is related to the design of the width and thickness of the crank arm. Is set to have a width or thickness corresponding to each shaft torque, the same effect as that of the assembly type can be obtained. In particular, in a mass-produced engine in which the inertia mass of the application and the load system is constant, a great effect can be expected by designing the shaft portion torque finely for each crank throw.

[0021]

As described above, according to the present invention, according to the first aspect of the present invention, the crankshaft of a large marine multi-cylinder internal combustion engine equipped with a propeller is a shaft obtained by torsional vibration calculation.
A crank arm having a maximum dimension and a maximum thickness capable of transmitting the maximum torque of the torsional torque of the portion, and / or a width and / or a thickness greater than the maximum to the extent that the torque can be transmitted; Since the crank arm has a reduced dimension, the crank arm has a reduced dimension corresponding to the transmission torque, the weight of the crankshaft can be reduced, and the manufacturing cost can be reduced. In addition, this reduces the rotational inertial mass that affects torsional vibration and increases the torsional vibration resonant rotation speed. Further, the mass of the crank arm can be adjusted within a range in which torque can be transmitted, and the dynamic balance of the engine can be improved.

In the second aspect of the present invention, since the reduced dimension is applied to the width of the crank arm, the weight can be easily and significantly reduced.

According to the third aspect of the present invention, a crank arm having a reduced dimension is applied to an assembling type crankshaft by shrink-fitting or the like. In addition, the size can be reduced, and the weight can be reduced. In addition, since the assembled crankshaft is generally used for a large marine engine, the effect of reducing the weight becomes more useful. That is, there is also an effect that the amount of load on the ship can be increased.

[Brief description of the drawings]

FIG. 1 shows the shape of a crank throw having a reduced width among crank throws to which the present invention is applied, (a) is a front view, and (b) is a longitudinal sectional view of a portion including a crank pin cross section.

FIGS. 2A and 2B show a shape of a crank throw having a maximum width among crank throws to which the present invention is applied, wherein FIG. 2A is a front view and FIG. 2B is a longitudinal sectional view of a portion including a crank pin cross section.

FIG. 3 is a front view showing a virtual schematic overall structure of the crankshaft to which the present invention is applied, in which all crank throws are rotated to the same position.

FIG. 4 is a curve diagram showing a calculation result of a shaft portion torsional torque in a torsional vibration calculation of a crankshaft to which the present invention can be applied.

[Explanation of symbols]

1a, 1b to 10a, 10b Crank arm (arm portion) 1a, 1b to 6a, 6b Crank arm of reduced size 7a, 7b to 9a, 9b Crank arm of maximum size 10a, 10b Crank arm of reduced size 11-21 Crankshaft Part (shaft part) T Thickness (thickness, maximum thickness) W, w Width (reduction width, reduction dimension) W ', w' Width (maximum width, maximum dimension)

Claims (3)

(57) [Claims] An arm portion having a width and a thickness as dimensions and a shaft portion, wherein said arm portion has a shaft;
The end on the partial side forms a semicircular outer periphery having the same diameter as the width.
In the crankshaft for marine large multi-cylinder internal combustion engine propeller is equipped with a crankshaft and said plurality of arm portions, said shaft obtained by the frequency calculation torsional among the width and the thickness up to that with the largest dimension is the largest among the dimensions with the maximum width and maximum thickness torque is the maximum width and thickness of the can transfer, the width or the thickness of the portion of the torsional torque at least one is not smaller than the maximum width or the maximum thickness in a range capable of transmitting a torsional torque of the shaft portion of the
Having a reduced dimension that is a dimension reduced from said maximum dimension . 2. The plurality of arm portions having a maximum dimension having a maximum width and a maximum thickness capable of transmitting a maximum torque, and a reduction having a width smaller than the maximum width in a range capable of transmitting the torque. The crankshaft according to claim 1, wherein the crankshaft has a width. 3. The crankshaft according to claim 1, wherein said arm portion and said shaft portion are assembled and formed.