JP3628644B2 - Crank journal bearing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reciprocating machine such as a reciprocating internal combustion engine such as a diesel engine or a gasoline engine, a reciprocating external combustion engine, a reciprocating pump, or a reciprocating compressor. The present invention relates to a main bearing device for rotatably supporting a journal (crank journal: also called a main shaft).
[0002]
[Prior art]
As shown in FIG. 6, the crank mechanism 10 is generally composed of a main bearing device that rotatably supports a crankshaft 11 and a crank journal (rotary main shaft) 12 thereof. The main bearing device is generally provided with semi-cylindrical flat bearing metals 3 and 4 (see FIG. 3) which are divided into two vertically. And between the crank journals 12 and 12 rotatably supported by the main bearing device, a pair of opposed crank webs (crank arms) 15 are integrally connected to the end of the crank journal 12 with an interval in the axial direction. The crank webs 15 and 15 are connected by a crank pin 14 at a position opposite to the connecting position of the crank journal 12 (most distant). For example, in the case of a crosshead type internal combustion engine, the other end of a connecting rod having one end connected to a piston in a cylinder via a crosshead pin is connected to the crankpin 14. Further, an input / output outward flange 5 is integrally formed at the outer peripheral surface end portion of the rightmost crank journal 12. In the figure, reference numeral 2 denotes a bearing base, 3 denotes a lower flat bearing metal, 4 denotes an upper flat bearing metal, and 6 denotes a bearing cap.
[0003]
By the way, in recent years, for example, in a diesel engine of a marine engine, there is a strong tendency to increase the stroke of the piston, that is, to increase the stroke of the piston in order to save fuel. This is nothing but a long stroke, because the combustion gas in the combustion chamber is easily replaced with fresh air, and the combustion state is improved and the thermal efficiency is improved, so that fuel consumption can be reduced. On the other hand, however, the crank web is easily deformed as much as it is extended, and the crankshaft is elastically deformed each time a revolution is applied to the crankshaft due to the explosive force in the cylinder and the inertial force of the piston. The crank journal is inclined with respect to (see FIG. 1), and a large unbalanced load due to contact with the journal is applied to the inner peripheral surface of the main bearing supporting the journal together with the force. If this state continues, if the main bearing metal that is in contact with and supports the outer peripheral surface of the journal portion is worn or damaged in a short period of time, or if the surface of the main bearing metal is lined, etc. May peel off.
[0004]
Therefore, as a measure for solving the above inconvenience, a method described in the following publication has been proposed.
[0005]
(1) JP-A-6-307430: At least the height of each main bearing is set according to the bearing load acting on each main bearing supporting a plurality of journals of the crankshaft, and the strength and rigidity of each main bearing are set. Maintain a good balance.
[0006]
(2) Japanese Patent Laid-Open No. 9-144759: By providing a large number of concave holes in a bearing saddle (bearing base) that supports the lower surface side of a half-cylindrical lower main bearing metal divided into two parts, The generated high oil film pressure is elastically deformed and leveled.
[0007]
(3) Japanese Utility Model Laid-Open No. 2-130419: The shaft portion of the crankshaft is formed in a continuous shape, and the vicinity of the central portion in the axial direction of the bearing portion is a cylindrical surface having a linear portion substantially parallel to the axis. By forming convex end surfaces on both sides of the shaft with a convex curved surface that forms a substantially uniform gap with respect to the continuous concave curved surface of the shaft, the oil is retained in the vicinity of the center during low-speed rotation and at high speed rotation. Occasionally, uniform bearing gaps at the ends of both shafts keep the flow resistance low, improve the cooling action of the bearings, and maintain the oil viscosity appropriately.
[0008]
(4) Japanese Patent Laid-Open No. 10-259819: In a bearing portion that receives axial axial thrust force, a surface that contacts the crankshaft is formed in a tapered shape, so that the bearing portion is deformed by the thrust force, and is formed on the inner surface of the bearing portion. This prevents excessive surface pressure from occurring due to the local contact of the crankshaft.
[0009]
[Problems to be solved by the invention]
However, the following inconveniences remain in the handling methods described in the above publications. That is,
(1) In the case of Japanese Patent Application Laid-Open No. 6-307430, there is little effect on contact per piece due to the inclination of the crank journal.
[0010]
{Circle around (2)} In the case of Japanese Patent Laid-Open No. 9-144759, the strength of the main bearing and the surrounding bearing stand is lowered.
[0011]
(3) In the case of Japanese Utility Model Laid-Open No.2-130419, the structure of the main bearing and the crankshaft becomes complicated, which causes an increase in cost.
[0012]
(4) In the case of Japanese Patent Laid-Open No. 10-259819, the bearing of the bearing portion that receives the axial thrust force is an object, but it cannot be applied as it is because the purpose is not to cope with the inclination of the crank journal targeted by the present invention. .
[0013]
The present invention has been made in view of the above points.When the crankshaft receives an explosive force or the like during engine operation and the crank journal is inclined due to elastic deformation, there is a risk of applying an offset load to the main bearing. It is intended to provide a crank journal bearing device that expands according to the inclination and uneven load of the crank journal, disperses and leveles the load force, can operate the engine stably for a long period of time, has a simple structure, and is easy to manufacture. is there.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, a crank journal bearing device according to the present invention has a flat surface parallel to the normal center axis of the crankshaft on the inner peripheral surface of the main bearing that rotatably supports the journal portion of the crankshaft. The peripheral surface was machined, and part of the surface was cut so that it gradually became deeper along the direction of inclination according to the degree of inclination and eccentric load of the journal acting on the main bearing surface during engine operation. It is characterized by.
[0015]
According to the bearing device for a crank journal according to claim 1 having the above-described configuration, even if the crank journal is inclined with respect to the main bearing due to, for example, an explosive force from a cylinder of an engine, the journal is moved along the inclination direction of the journal. Since the inner peripheral surface of the main bearing is cut, the journal is supported by the inclined inner peripheral surface of the main bearing, so the load force is distributed and leveled, and an excessively large load is applied to the main bearing. There is no so-called one-sided contact that acts on. In other words, even if each journal of the crankshaft is tilted to one side with respect to the normal axial direction, there is a surface on which the load is applied almost evenly on the inner peripheral surface of the main bearing, and the main bearing is worn out in a short period of time. It can be used stably for a long time without being damaged.
[0017]
In addition, with the above configuration, when the crankshaft is elastically deformed during one rotation and the crank journal is inclined, a single contact occurs and an uneven load is applied to the inner peripheral surface of the main bearing. By supporting the crank journal with the cutting part that has been processed to gradually deepen, the uneven load is distributed and leveled and supported, while the uneven load state is instantaneous (temporary) during one revolution of the crankshaft. Therefore, when the crank journal at other times rotates with a small inclination and substantially parallel to the central axis (it is longer in time to rotate substantially parallel to the central axis of one rotation) The crank journal can be rotatably supported by a flat peripheral surface parallel to the central axis. Therefore, the crank journal can hardly rotate against the inner peripheral surface of the main bearing regardless of the state of the crank journal, and can be stably supported for a long time.
[0018]
According to a second aspect of the present invention, the main bearing includes a semi-cylindrical flat bearing metal that is divided into upper and lower parts, and an inner peripheral surface of the lower flat bearing metal is inclined with respect to the axial direction of the journal. It can be gradually cut.
[0019]
According to the bearing device of the second aspect, only the lower flat bearing metal of the upper and lower flat bearing metals may be cut, or a lower flat bearing metal that has been cut in advance is prepared. If so, it can be replaced immediately when the lower flat bearing metal is worn. Of the upper and lower flat bearing metals, the lower flat bearing metal is susceptible to abrasion, as described above, because the explosive force in the cylinder and the inertial force of the piston are added to the load of the crank journal. It is because it acts on.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a bearing device for a crank journal according to the present invention will be described below with reference to the drawings.
[0021]
FIG. 1 (a) is an enlarged perspective view of the bearing device according to the embodiment of the present invention with the lower flat bearing metal removed and seen from above, and FIG. 1 (b) is a bearing device according to another embodiment of the present invention. It is the expansion perspective view which removed the lower side flat bearing metal and was seen from upper direction. FIG. 2 is a cross-sectional view showing the entire bearing device of FIG. 1, and shows a part A of the main bearing device that supports one journal of the crankshaft of the two-cycle diesel engine for large ships shown in FIG. FIG. 3 is a perspective view of the main bearing device taken out of the two divided bearing metals. FIG. 4 is a cross-sectional view of the main bearing device of a two-cycle diesel engine for a large marine vessel that supports one journal of the crankshaft, with a part omitted. FIG. 5 is a perspective view showing a part of a two-cycle diesel engine for a large vessel provided with a bearing device for a crank journal according to an embodiment of the present invention.
[0022]
As shown in FIGS. 4 and 5, the crank mechanism 10 of this example is for a two-cycle diesel engine for an in-line six-cylinder large vessel, and the crankshaft 11 is moved downward from each piston 18 that reciprocates in the cylinder 19 in the vertical direction. A plurality of sets of crank webs 15 are provided for connecting the other end of the connecting rod 13 having one end connected to the lower end of the piston rod 17 extending through the cross head pin 16 via the crank pin 14. Further, a crank journal (crankshaft) 12 is disposed at one end of the crank web 15, and a semi-cylindrical flat bearing metal 3 · 4 divided into two vertically as shown in FIG. Support for rotation. On the inner peripheral surfaces of the flat bearing metals 3 and 4, long grooves 3a and 4a for supplying lubricating oil are formed in particular on the upper side.
[0023]
As shown in FIG. 2, in the main bearing device 1, a lower flat bearing metal 3 is fitted on a semicircular concave portion 2 a of a bearing base 2, and a crank journal 12 is supported on the flat bearing metal 3. The upper flat bearing metal 4 is covered. Further, a bearing cap 6 is placed on the upper flat bearing metal 4 and fastened by a nut 8 that is screwed into a threaded portion of the fastening bolt 7.
[0024]
As shown in FIG. 1 (a), the crankshaft is formed on the inner peripheral surface of the flat bearing metal 3, 4 which is a characteristic part of the present invention, particularly on the inner peripheral surface of the lower flat bearing metal 3. 11 is elastically deformed so that the crank journal 12 inclines, that is, in the case of this example, the cutting depth gradually increases along the direction L inclined downward to the left side by α ° with respect to the central axis S. It is continuously and smoothly cut (so that there is no step). The arcuate line h in FIG. 1A showing the cutting portion 3b represents a contour line, and the difference in cutting depth between the contour lines h is 0.05 mm in this example. In the case of this example, as is clear from FIG. 1A, the rear end side edge at a position of 45 ° from the neutral position (0 °) on the inner peripheral surface of the lower bearing metal 3 to the clockwise direction (left side). However, when the cutting amount is 0.3 mm, the maximum cutting amount, that is, the thinnest wall portion, corresponds to the maximum uneven load due to the contact of the journal 12 with one piece. At this time, the inclination angle α is 0.14 °.
[0025]
In addition, the inner peripheral surface of the lower flat bearing metal 3 is cut by the cutting portion 3b that gradually becomes deeper in the inner peripheral surface of the bearing metal 3 along the inclination direction L of the crank journal 12 as described above. The inner peripheral surface 3c that is parallel to the central axis S and is flat (the thickness between the outer peripheral surface and the inner peripheral surface is constant) is processed in the same manner as a conventional flat bearing metal. That is, the cutting portion 3b on the inner peripheral surface of the lower flat bearing metal 3 is provided in a part of the flat inner peripheral surface 3c, and the proportion occupied by the cutting portion 3b is the crank journal 12 as shown in FIG. It is changed by the inclination and the eccentric load due to the elastic deformation. That is, FIG. 1B shows an embodiment in which the crank journal 12 has a larger inclination than that in FIG.
[0026]
Furthermore, the upper flat bearing metal 4 may be provided with a cutting part similar to the above in point symmetry with the cutting part 3b or not at all, depending on the mode of elastic deformation of the crankshaft 11. change.
[0027]
By the way, the cutting portion 3b is provided on a part of the flat inner peripheral surface 3c of the lower flat bearing metal 3 as described above. This is because the crank journal 11 is elastically deformed while the crankshaft 11 is rotated once. It is momentary (temporary) that an offset load is exerted by inclining, and in other cases, the inclination is small and rotating in a state substantially parallel to the central axis S. This is because the crank journal 12 can be sufficiently supported at this time in consideration of the long time of rotation in a substantially parallel state.
[0028]
In the case of this example, since the engine has 6 cylinders, the main bearing device 1 that supports the crank journal 12 is arranged at seven locations. The cutting parts 3b are machined in the inclination direction L according to the inclination of the crank journal 12 and the degree of the eccentric load of the flat bearing metals 3 and 4 of each main bearing device 1 that may be worn.
[0029]
Although one embodiment related to the bearing device for the crankshaft of the present invention has been described above, the bearing device of the present invention includes, for example, the above-described marine diesel engine, a four-cycle engine, an automobile diesel engine, and other internal combustion engines, and Needless to say, the present invention can be applied to bearing devices for various crankshafts as a conversion mechanism between reciprocating motion and rotational motion in reciprocating machines such as external combustion engines, reciprocating compressors and reciprocating pumps.
[0030]
【The invention's effect】
As apparent from the above description, the crankshaft bearing device of the present invention has the following excellent effects.
[0031]
(1) Since only the cutting portion is provided on the inner peripheral surface of the main bearing in accordance with the inclination of the crank journal and the degree of the eccentric load, the structure is simple, the manufacture is easy, and the manufacture is possible at a relatively low cost.
[0032]
(2) Since the journal is supported almost entirely on the inner peripheral surface of the main bearing, the load force is distributed and leveled, and an excessively large load does not act on the main bearing. In other words, even if each journal of the crank is inclined to one side with respect to the normal axial direction, the load acts on the inclined inner peripheral surface of the main bearing almost evenly. The receiver is not worn or damaged and can be used stably over a long period of time.
[0033]
(3) As described above, when the crankshaft is elastically deformed during one rotation and the crank journal is tilted to cause one-side contact and exert an uneven load on the inner peripheral surface of the main bearing, the tilt direction Since the crank journal is supported by the cutting part that has been processed to become deeper along the axis, the uneven load can be distributed and leveled, and since the unbalanced load is momentary during one revolution of the crankshaft, Even when the crank journal rotates in a state parallel to the central axis without tilting, the crank journal can be rotatably supported by a flat peripheral surface parallel to the central axis, so that the inner peripheral surface of the main bearing is It is difficult to wear and can stably support the crank journal in a stable manner for a long time.
[0034]
(4) In the invention according to claim 2 , the lower flat bearing metal may be cut only among the upper and lower flat bearing metals, or a lower flat bearing metal that has been cut in advance is prepared. Therefore, when the lower flat bearing metal is worn, it can be replaced immediately.
[Brief description of the drawings]
FIG. 1 (a) is an enlarged perspective view of a bearing device according to an embodiment of the present invention from which a lower flat bearing metal is removed and viewed from above, and FIG. 1 (b) is another embodiment of the present invention. It is the expansion perspective view which removed the lower flat bearing metal of the bearing device concerned, and was seen from the upper part.
2 is a cross-sectional view showing the entire bearing device of FIG. 1, and shows part A of the main bearing device that supports one journal of the crankshaft of the large-cycle two-cycle diesel engine shown in FIG. Yes.
FIG. 3 is a perspective view showing a bearing metal divided into two parts of the main bearing device.
FIG. 4 is a cross-sectional view showing a part of a main bearing device of a large-cycle two-cycle diesel engine supporting one journal of a crankshaft with a part thereof omitted.
FIG. 5 is a perspective view showing a part of a two-cycle diesel engine for a large vessel provided with a bearing device for a crank journal according to an embodiment of the present invention.
FIG. 6 is a front view showing a conventional crank mechanism for a general six-cylinder engine, and a part thereof is shown in cross section.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Main bearing apparatus 2 Bearing base 2a Semi-circular concave part 3 Lower flat bearing metal 3b Cutting part 3c Flat part 4 Upper flat bearing metal 5 I / O outward flange 6 Bearing cap 7 Fastening bolt 8 Nut 10 Crank mechanism 11 Crankshaft 12 Crank journal (crankshaft)
13 Connecting rod 14 Crank pin 15 Crank web 16 Cross head pin 17 Piston rod 18 Piston 19 Cylinder S Normal center axis of the crankshaft or axis L parallel to it The inclination direction of the crank journal or the cutting center axis α S and L parallel to it Angle of intersection Z S and L

Claims (2)

On the inner peripheral surface of the main bearing that rotatably supports the journal part of the crankshaft, a flat peripheral surface that is parallel to the normal center axis of the crankshaft is machined, and part of the main shaft is rotated during engine operation. A crank journal bearing device, wherein the journal is cut so as to become gradually deeper along the inclination direction of the journal acting on the receiving surface in accordance with the inclination and the degree of the eccentric load. The main bearing is provided with a semi-cylindrical flat bearing metal that is divided into upper and lower parts, and the inner peripheral surface of the lower flat bearing metal is gradually cut in a direction inclined with respect to the axial direction of the journal.
The bearing device for a crank journal according to claim 1 .

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