JP2002333007A - Internal combustion engine driving propeller shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a load capacity of a thrust bearing in an internal combustion engine. SOLUTION: A rearmost main bearing 5 of the internal combustion engine is arranged between a throw of a crankshaft and a thrust cam inside the thrust bearing. A thrust segment 20 is arranged between a forward facing sliding face 22 on the thrust cam and a rearward facing supporting face 18 on a fixed type main bearing housing. Within a circumferential area, the thrust cam 14 has a rotationally symmetric arc shaped recessed part 28 extending radially inward to a position of a height not exceeding an intermediate portion of the thrust segment 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine which drives a propeller shaft and has a thrust bearing (thrust bearing) at the rearmost main bearing (main bearing). The thrust cam is arranged in the axial direction between the throw of the crankshaft and the thrust cam of the thrust bearing, the thrust cam being rotatable together with the crankshaft, and the axially forward facing sliding surface on the thrust cam and the bed plate of the internal combustion engine. Main bearing fixing (installation type)
The invention relates to an internal combustion engine in which a thrust segment is arranged between an axially rearwardly facing support surface on a housing.

[0002]

BACKGROUND OF THE INVENTION Internal combustion engines having such thrust bearings integrated into the bedplate at the rearmost main bearing of the engine result in an advantageously shortened engine length. This internal combustion engine is typically the main engine of a large ship, such as a container ship, which must transmit very large torque from the engine to the propeller through a propeller shaft. As the propeller propels the ship forward, the propeller exerts a forward force on the propeller shaft, which is transmitted to the engine foundation through the bedplate in the thrust bearing.

[0003] The transfer of force from the rotating shaft to the bed plate takes place via a thrust segment which is substantially stationary with respect to the support surface on the main bearing housing. The sliding surface of the thrust cam slides on the support surface of the thrust segment, and the lubricating system of the thrust bearing maintains a lubricating oil film between the bearing surface and the sliding surface.

[0004]

The individual thrust segments are individually adjusted with respect to the thrust cam, and the total load capacity of the thrust bearing corresponds to the sum of the load capacities of the individual thrust segments. For this reason, it is desirable that the load capacity of the thrust segment be reasonably uniform during operation, but this will result in the thrust segment being located in the upper sector portion opposite the removable upper portion of the main bearing. This is difficult in the case of a thrust bearing integrated into the main bearing, since there is no such thing. Therefore, the upper portion of the thrust cam at that time is not axially supported by the thrust segments.

An object of the present invention is to improve the load capacity of a thrust bearing in an internal combustion engine.

[0006]

In view of this, the internal combustion engine has a rotationally symmetrical configuration in which the thrust cam extends radially inward in the peripheral region to a position where the thrust cam is at most as high as the middle part of the thrust segment. It is characterized by having an arcuate concave portion.

In a full load operation in which the load capacity of the thrust bearing (thrust bearing) is maximized, the presence of the arc-shaped concave portion in the peripheral region is caused by the fact that the thrust cam moves in the radial direction of the thrust segment in the peripheral region. It means that the degree of pressing against the outermost region is slightly weak.

First, this means that the center of the thrust moves somewhat inward in the radial direction. The fixed (installed) part of the main bearing (main bearing)
It is formed integrally with the transverse wall in the bed plate, which is made of a heavy material and provided with rib-shaped stiffeners. As a result, the support surface is more rigid in its radially outermost region than in its radially innermost region adjacent to the shaft bore of the main bearing.
When subjected to an operating load, the stiffer areas of the support surface are less deformed in the axial direction, so that the load applied to the thrust segment in the radially outermost area is likely to be maximum. The presence of the arc-shaped recess in the thrust cam reduces the axial pressure from the thrust cam in the radially outermost region and thus compensates for the greater stiffness of the bearing surface in this region.

Second, the arc-shaped recess makes the pressure distribution in the region of the thrust bearing more uniform, in which the thrust cam changes from the unsupported state to the supported state. In the non-supporting area of the thrust cam, its peripheral area becomes more flexible, and as the peripheral area rotates continuously in the supporting area, the degree of this bending is reduced, so that the excess thrust segment initially becomes excessive for the arranged thrust segments. Load is applied. Partially compensating for this excess load is achieved by an arc-shaped recess that reduces the thrust load on the segment, especially in the radially outermost region where the thrust cam deflection is greatest. Decrease.

If the recess extends more radially inward than the middle of the thrust segment, the maximum thrust force that can be conducted by the segment may be undesirably reduced.

[0011] Preferably, the arc-shaped recess extends inward to a position at most as high as the radially outermost thirty percent of the thrust segment. This is because the radially innermost region, which may be subject to the largest possible thrust force, may comprise a preferably large thrust segment region.

In one preferred embodiment, the arcuate recess is located on the outer surface of the thrust cam. The recess provides the thrust cam with greater flexibility in the radially outermost region. When the force applied to the thrust bearing is small, the pressure applied to the thrust cam is excessively low so that the thrust cam is not deformed and the sliding surface extends substantially parallel to the support surface. When the pressure on the thrust cam is high, the radially outermost region facing the recess deflects axially toward the recess due to the greater flexibility provided by the recess. This deflection means that a greater proportion of the thrust load is absorbed by the radially inner region of the thrust segment. in this way,
In this embodiment, depending on the load, the sliding surface itself is adjusted to a shape that allows a sufficient and suitably thick lubricating oil film to be maintained between the thrust segment and the sliding surface. Brings the advantage of doing so.

[0013] In one embodiment, the arc-shaped recess is associated with at least one tube so as to be able to supply coolant. By supplying coolant, usually lubricating oil, to the arc-shaped recess, the cooling acts on both the front and back surfaces of the radially outermost region of the thrust cam, so that the temperature can be kept low, This means
Since it is possible to conduct a larger thrust force without the lower temperature lubricating oil being compressed and removed,
It contributes to improving the load capacity. Since the coolant does not have to perform a lubricating function in the arcuate concave portion, the supply amount can be exclusively adapted to the required cooling effect.

In one embodiment, the thrust cam in the internal combustion engine has a radially projecting collar to which the sprocket wheel is fixed at a location radially outside the arcuate recess. In some cases, for example, to drive the camshaft at the rear end of the engine, the chain drive is provided with a thrust bearing, and in that case the sprocket wheel is provided with a thrust cam provided by an arc-shaped recess. This will limit the flexibility of the radially outermost region. By fixing the sprocket wheel to the collar, the sprocket wheel is fixed only to the thrust cam at one side of the arc-shaped recess, so that the opposite side of the recess completely retains the desired flexibility I do.

In one alternative design, the thrust cam has two cylindrical surfaces in the axial direction on each side of the arc-shaped recess, and the two annular members of one sprocket wheel are It is fixed to each one of the cylindrical surfaces. Dividing the sprocket wheel into two members that are suitably mutually flexible in the axial direction also prevents the sprocket wheel from overcoming the flexibility of the radially outermost region of the thrust cam. Also.

Alternatively, an arc-shaped recess may be provided on the sliding surface of the thrust cam facing forward in the axial direction.
However, this results in a longer distance in the radially outermost region than in the radially innermost region between the sliding surface and the supporting surface in the unloaded thrust bearing, which means that When the load is low, the thickness of the oil film in the outermost region in the radial direction is considerably increased. However, this does not cause any operational problems. The thrust bearing receives the full load,
When the radially outermost region flexes more than the radially innermost region, the distance between the sliding surface and the support surface becomes more uniform, which facilitates equalizing the load applied to the thrust segments. In addition, the load capacity is increased.

As a result of the uniform loading of the thrust segment over its radial extension, the present invention provides a very large two-stroke crosshead engine of the diesel type with a maximum continuous rating of at least 40,000 kW. Particularly useful. Typically, for example, 70 to 20
Due to the very high power delivered at low rpm in the range of 0 rpm, the axial thrust force is very high and the thrust bearing has a correspondingly large thrust segment area. For this reason, the thickness of the oil film between the segment and the sliding surface is thinner than the size of the thrust segment, and the influence of the irregular distribution of the thrust force across the segment on the load capacity can be ignored. Can be on the order of magnitude.

Next, an example of an embodiment of the present invention will be described in more detail with reference to the drawings of a schematic diagram.

[0019]

FIG. 1 shows an internal combustion engine 1 connected to a propeller shaft 3 carrying a propeller 4 via an intermediate shaft 2.
Is illustrated. The engine may be a four-stroke engine or a two-stroke engine such as Applicant's ME or MC two-stroke crosshead engine well known to those skilled in the art. The engine has, for example, a bore ranging from 30 cm to 120 cm,
With a large number of cylinders in the range of 5 to 20, and as found in the case of crosshead engines, the engine can be in the range of 60 to 300 rpm. The output of this engine is, for example, 3,
It can range from 000 kW to 130,000 kW. The engine preferably has a relatively large output, such as 30,000 kW, and has at least eight cylinders and a bore size of at least seven.
Should be 0 cm.

At its rearmost main bearing 5 with respect to the crankshaft 6, the internal combustion engine 1 is shown in the rear view of FIG.
Has a thrust bearing 7 shown in the longitudinal sectional view of FIG. The main bearing 5 has a fixed (installed) housing which is cast integrally with the transverse wall in the engine bed plate 8. This wall is reinforced with relatively large ribs 9 so as to obtain great rigidity. The main bearing housing further comprises a removable upper part 10.
The surface of the main bearing housing is provided with a bearing metal 11 on its inner surface which defines a shaft hole, in which journal 12 is arranged, which journal is located in the rearmost throw of the crankshaft. It is connected to the crank arm 13 and is formed integrally with the thrust cam 14 in the thrust bearing. On the rear side of the thrust cam, the same shaft part is continuous in a journal 15 which is journalled in the rearmost shaft bearing 16. This journal 15 terminates in a flange 17 so that it can be clamped directly to the intermediate shaft 2 or the propeller shaft 3, depending on the distance between the rear end of the engine and the stern tube of the hull.

The rear side of the fixed (stationary) main bearing housing is arranged around the lower part of the main bearing in a plane perpendicular and substantially perpendicular to the longitudinal centerline 19 of the main bearing. There is an annularly extending support surface 18. In the embodiment shown, the support surface extends a distance of 22/36 of the circumference of the shaft. On the support surface, Mitchell
Some of the molds, for example eight thrust segments 20, are arranged. These segments are held in place by a yoke 21 that extends axially beyond the sides of the two top thrust segments, so that they cannot rotate with the thrust cam. The yoke 21 is removable, which makes it possible to remove the thrust segments without removing the shaft with the thrust cam from the thrust bearing. Instead of a yoke, two overhanging collars can be used on the detachable part of the main bearing housing, or two separate end stops can be detachably fixed to the bearing housing.

On the side facing the support surface, the thrust segment 20 has a radially extending edge around which the segment tilts so that it can adjust to the load from the thrust cam. it can. The thrust segment is flat at its two bearing surfaces facing in the direction of the thrust cam.

The thrust cam has a forward facing sliding surface 22 that is rotationally symmetric and extends substantially parallel to the support surface 18. The sliding surface is pressed against the thrust segment by the forward axial force corresponding to the propeller's propulsion force, and a lubricant film is continuously formed between the sliding surface and the bearing surface of the thrust segment. Lubricating oil is U
It is supplied from a discharge pipe 23 that supplies lubricating oil to a letter-shaped distribution pipe 24. The distribution pipe extends downward through the radially innermost portion of the thrust segment, as shown in the right segment of FIG. Several spray tubes 25 branch off from the distribution line, for example, to supply lubricating oil to the thrust segments in such a way that a separate spray tube is arranged in each of the thrust segments.

The above-described thrust segment is effective only when the boat is driven forward by the engine 1. If the engine is fixed to the propeller shaft by a constant pitch propeller, it is necessary to reverse the direction of rotation of the engine in order to reverse the ship.

In order to absorb the axial rearward force generated during the reverse movement, the thrust bearing is designed as a double-acting thrust bearing, and the thrust cam is provided so that the front of the shaft bearing 16 is directed axially forward. It may further have a secondary annular sliding surface 26 for the associated secondary thrust segment 27 arranged on the surface.

At the outer periphery facing outward in the radial direction, FIG.
The thrust cam shown in FIG. 1 has an arc-shaped concave portion 28 which extends rotationally symmetrically around the entire circumference of the thrust cam.
This arc shape is chosen in each case according to the stresses in the thrust cam common in engines. The arc shape may be, for example, parabolic, elliptical, or any other suitable curved shape.

The distance a shown in FIG. 3 extends radially from the outer circumference of the thrust cam at the same height as the starting point of the concave portion 28 to one point at the same height as the middle portion of the extension of the thrust segment in the radial direction. . In the embodiment of FIG.
The recess extends over a radial distance corresponding to approximately 25 percent of the radial extension of the thrust segment. To transmit high thrust forces, it is preferred that a portion of the thrust segment be supported by a solid, inflexible material within the thrust cam as much as possible.
This recess reduces the axial stiffness of the thrust cam so that the radially outermost region of the thrust cam extends elastically in the axial direction.

It is possible to arrange a sprocket wheel 29 on the outer periphery of the thrust cam 14. The sprocket wheel is in the form of a toothed rim whose number of rows of teeth 30 corresponds to the number of chains of the chain drive. FIG. 4 illustrates one embodiment in which a sprocket wheel 29 is secured to a collar 31 that projects radially from the outer surface of the thrust cam. This fixing is performed by bolting. The sprocket wheel with the associated collar 31 is freely adjustable in the axial direction. In the embodiment of FIG. 4, the last row of teeth 30
Is disposed at a position displaced in the axial direction with respect to the fixed collar 31. Alternatively, the row of teeth 30 is a collar 31
The sprocket wheels may be mounted in a state where they are arranged symmetrically in the axial direction on both sides of the sprocket. In this case, the sprocket wheel can be shrink fitted to the collar or bolted by radially extending and / or axially extending bolts.

FIG. 5 illustrates one alternative embodiment in which the sprocket wheel is divided into two annular members 32, each of which is shrink fitted to a cylindrical surface 33 on the outer surface of the thrust cam. ing. These two annular members 32 are mutually elastic in the axial direction.

FIG. 6 shows another embodiment in which an arc-shaped recess 28 ′ is arranged on the sliding surface 22 facing the thrust segment 20. This recess 28 '
Can be a parabolic profile or any other profile that provides the appropriate stress distribution within the material. When the bearing is unloaded, the radially outermost edge is located at a distance b further away from the bearing surface in the thrust segment 20. When the bearing is fully loaded, a load is applied to the radially outermost region of the thrust cam, which region is deformed axially toward the thrust segment. This deformation is such that the sliding surface and the support surface are substantially parallel at full load.

Combining the details of the various embodiments,
A new embodiment can be adopted.

[Brief description of the drawings]

FIG. 1 is a side view of an internal combustion engine according to the present invention.

FIG. 2 is a rear view of a thrust bearing of the internal combustion engine of FIG. 1;

FIG. 3 is a sectional view of the thrust bearing of FIG. 2;

FIG. 4 is a view of a segment part corresponding to FIG. 2 according to another embodiment of the present invention;

FIG. 5 is a view of a segment part corresponding to FIG. 2 according to still another embodiment of the present invention;

FIG. 6 is a sectional view of a thrust cam and a thrust segment according to a further embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intermediate shaft 3 Propeller shaft 4 Propeller 5 Main bearing 6 Crankshaft 7 Thrust bearing 8 Engine bedplate 9 Rib 10 Upper part of main bearing housing 11 Bearing metal 12 Journal 13 Crank arm 14 Thrust cam 15 Journal 16 Shaft bearing 17 Flange 18 Support surface 19 Longitudinal center line of main bearing 20 Thrust segment 21 Yoke 22 Sliding surface 23 Projection tube 25 Spray 26 Secondary annular sliding surface 27 Thrust segment 28, 28 'Arc-shaped recess 29 Sprocket wheel 30 tooth row of sprocket wheel 31 collar 32 annular member 33 cylindrical surface

Continued on the front page (72) Inventor Anders Vigo Hansen Deko-2720, Denmark, Denmark-2720 Vanrasse, Ahragevey 17 F term (reference) 3G024 AA00 AA55 BA28 DA00 DA02 DA12 EA10 FA00 FA01 FA07 3J033 AA02 AA05 AA10 GA09

Claims (9)

[Claims] An internal combustion engine that drives a propeller shaft and has a thrust bearing on a rearmost main bearing thereof, the main bearing comprising a thrust of a crankshaft (6) and a thrust bearing in an axial direction of the crankshaft. Placed between the thrust cam and
The thrust cam is rotatable with the crankshaft, the axially forwardly facing sliding surface on the thrust cam and the axially rearwardly facing support surface on the fixed housing of the main bearing in the bed plate (8) of the internal combustion engine. 18), wherein the thrust cam extends radially inward to a position flush with at most the middle part of the thrust segment (20). Symmetric arc-shaped recesses (28, 28 ')
An internal combustion engine comprising: 2. The internal combustion engine according to claim 1, wherein the arc-shaped recess (28 ') is at most as high as the radially outermost 30% of the thrust segment (20). An internal combustion engine characterized by extending inward. 3. The internal combustion engine according to claim 1, wherein the arc-shaped recess (28) is arranged on an outer surface of a thrust cam. 4. The internal combustion engine according to claim 3, wherein the arc-shaped recess (28) is associated with at least one pipe so as to be able to supply coolant. 5. The internal combustion engine according to claim 3, wherein the thrust cam has a radially projecting collar, and a sprocket at a position radially outside the arc-shaped recess (28, 28 '). Internal combustion engine characterized in that wheels (29) are fixed to the collar. 6. The internal combustion engine according to claim 3, wherein the thrust cam has two cylindrical surfaces axially on each side of an arc-shaped recess (28). Two annular members of the sprocket wheel (3
An internal combustion engine characterized in that 2) is fixed to each one of said cylindrical surfaces. 7. The internal combustion engine according to claim 6, wherein the two annular members of the sprocket wheel are mutually flexible in the axial direction. 8. The internal combustion engine according to claim 1, wherein the arc-shaped recess (28 ') is arranged on a sliding surface (22) of a thrust cam facing forward in the axial direction. The internal combustion engine. 9. The internal combustion engine according to claim 1, which is a diesel two-stroke crosshead engine having a maximum continuous rating of at least 40,000 kW. organ.