JP2001303901A - Diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diesel engine so constituted as to be miniaturizable. SOLUTION: The diesel engine 10 has a guide mechanism allowing a crosshead 20 to connect a piston 14 to a connecting rod 16 to slide in a crank chamber C, the guide mechanism comprises a guide rail 28 extending in the sliding direction of the crosshead 20, and a guide shoe 23 having a slidable contact surface 23a fitted to the crosshead 20 and brought in slidable contact with the guide rail 28, and an oil groove 25 and a partial oil groove 26 are formed in the slidable contact surface 23a so that the crosshead 20 is covered with the guide rail 28 when the crosshead 20 is located at a bottom dead center.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine having a guide mechanism for sliding a crosshead in a crank chamber.

[0002]

2. Description of the Related Art Conventionally, a diesel engine having a guide mechanism for sliding a crosshead connecting a piston and a connecting rod in a crank chamber has been known. This guide mechanism is configured as follows. That is, guide rails that extend in the sliding direction of the crosshead are provided facing each other in the crank chamber, and a crosshead having a guide shoe that slides on the guide rail is interposed between the guide rails. An oil groove filled with lubricating oil is formed in the guide shoe, and the guide shoe slides smoothly on the guide rail. With such a configuration, the crosshead can be guided by the guide rail and reciprocate up and down in the crank chamber.

[0003]

In recent years, it has been demanded that the diesel engine be reduced in size for various reasons. To reduce the size of the diesel engine, it is effective to shorten the connecting rod. However, when the connecting rod is shortened, the trajectory of the crosshead reciprocating enters the turning radius of the arm of the crankshaft. However, as described above, the crosshead reciprocates while being guided by the guide rail. If the guide rail is provided within the rotation radius of the arm, a problem of interference between the arm and the guide rail occurs. Must be cut off, which causes a problem that the guide shoe is damaged. For this reason, the above-mentioned guide mechanism has been a factor that hinders downsizing of the diesel engine.

[0004] Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a diesel engine having a configuration capable of achieving compactness.

[0005]

SUMMARY OF THE INVENTION A diesel engine according to the present invention is a diesel engine having a guide mechanism for sliding a crosshead connecting a piston and a connecting rod in a crank chamber. A guide rail extending in the sliding direction of the crosshead, a guide shoe attached to the crosshead and having a sliding contact surface that slides on the guide rail, and a guide rail that covers the crosshead when located at the bottom dead center. And an oil groove formed on the sliding contact surface.

With this configuration, even when a part of the crosshead is exposed from the guide rail when the crosshead is located at the bottom dead center, the oil groove is exposed from the guide rail. There is no. Therefore, even if a part of the guide shoe protrudes from the guide rail toward the crankshaft,
Air does not enter the oil groove formed on the sliding contact surface, and the problem of damage to the guide shoe due to cavitation or the like caused by air entering the oil groove does not occur. As a result, while keeping the guide rail long enough to avoid interference with the arm, the bottom dead center of the crosshead that slides on the guide rail is lowered, and the connecting rod that connects the crosshead and the crankshaft is changed. Can be shorter.

[0007] In the above-mentioned diesel engine, the guide rail may be cut off so as not to interfere with the arm within the rotation radius of the arm of the crankshaft.

In this way, the guide rail is cut out so as not to interfere with the arm, and the tapered guide rail taper extends within the rotation radius of the arm, so that when the guide shoe is located at the bottom dead center, The oil groove can be formed so as to be covered by the tapered portion of the guide rail. This allows
Many oil grooves can be formed on the sliding contact surface, and the guide shoe can easily slide on the guide rail.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the diesel engine according to the present invention will be described below in detail with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a sectional view showing a diesel engine 10 according to an embodiment of the present invention, and FIG. 2 is a view of the diesel engine 10 viewed from an axial direction. As shown in FIG. 1, the diesel engine 10 includes a plurality of (in this case, four) cylinders 12, each of which has a piston 14 provided inside a jacket 36 and a reciprocating motion of each piston 14. And a crankshaft 30 connected to each connecting rod 18. A base plate 32 through which the crankshaft 30 is inserted;
Tie bolt holes (not shown) are formed in a frame 34 provided above the frame 34 and a jacket 36 provided further above the frame 34, respectively. And the base plate 32,
A tie bolt 38 is inserted into each tie bolt hole of the frame 34 and the jacket 36, and the members are fixed integrally.
The crankshaft 30 is supported by a thrust bearing 42,
The movement with respect to the base plate 32 is restricted. Crankshaft 3
The propeller 40 is attached to the tip of the
A longitudinal vibration damper 44 for suppressing longitudinal vibration accompanying rotation of the crankshaft 30 is provided (in some cases) at an end opposite to 0 (the right side in FIG. 1). Each crankcase C
Inside, a guide rail 28 for sliding the crosshead 20 near a partition plate 35 that partitions each cylinder 12 extends in the sliding direction. As shown in FIG. 2, each guide rail 28 is opposed via a crosshead 20, and a total of four guide rails 2 are provided in each crank chamber C.
8 are provided. The lower part of each guide rail 28 is cut out so as not to interfere with the arm 31 within the rotation radius R (see FIG. 2) of the arm 31 of the crankshaft 30. That is, as shown in FIG. 1, near the crankshaft 30, the guide rail 28 is
And the guide rail 28 is gradually narrowed in the vicinity of the rotation radius R of the arm 31.

Next, referring to FIG.
0 will be described. The crosshead 20 has a crosshead pin 21 that connects the piston rod 16 and the connecting rod 18. The crosshead pin 21 has a cylindrical shape, and has a concave portion 21 formed on the top of the crosshead pin 21.
The piston rod 16 is attached to a, and the crosshead pin 21 is rotatably supported by the bearing of the connecting rod 18. Two square connecting plates 22 are attached so as to sandwich the crosshead pin 21 in the axial direction. A guide shoe 23 having a sliding contact surface 23 a that slides on the guide rail 28 is attached to each of the connecting plates 22 on two sides parallel to the sliding direction of the crosshead 20. An oil groove 25 and a partial oil groove 26 (see FIG. 4) are formed on the sliding contact surface 23a of the guide shoe 23, and lubricating oil is supplied so that the guide shoe 23 can slide on the guide rail 28 smoothly. . The guide mechanism 29 includes a guide shoe 23 and a guide rail 28 (see FIG. 1).

The oil groove 25 and the partial oil groove 26 formed on the sliding contact surface 23a will be described with reference to FIG. FIG. 4 shows a case where the guide shoe 23 is located at the bottom dead center. A plurality of oil grooves 25 and partial oil grooves 26 are formed on the sliding contact surface 23a so as to be covered by the guide rail 28 when the guide shoe 23 is located at the bottom dead center. That is, when the guide shoe 23 is located at the bottom dead center, the side of the piston 14 (region L) of the guide shoe 23 is completely covered by the guide rail 28, so that the oil groove 25 is formed.
Are formed over both ends of the sliding contact surface 23a in the horizontal direction. On the other hand, the guide shoe 23 on the side of the crankshaft 30 (region M and region N) is covered with a tapered portion of a guide rail 28 that is partially cut away and has a reduced horizontal width. Therefore, the crankshaft 3 of the guide shoe 23
On the 0 side, a partial oil groove 26 having a length corresponding to the portion covered by the guide rail 28 is formed horizontally. Here, the reason why the oil groove 25 and the partial oil groove 26 are formed in the horizontal direction, that is, perpendicular to the sliding direction of the crosshead 20 is that when the crosshead 20 slides, the lubricating oil is This is to prevent the groove 25 and the partial oil groove 26 from being biased to one side.

Next, the diesel engine 1 according to this embodiment will be described.
The operation of 0 will be briefly described. First, each cylinder 1
The piston 14 reciprocates on the cylinder liner due to the explosion pressure in the second combustion chamber B, and this reciprocation is transmitted to the crosshead 20 via the piston rod 16. Crosshead 2
0 slides on the guide rail 28 and reciprocates up and down in the crank chamber C. The connecting rod 18 that rotatably supports the crosshead 20 swings as the crosshead 20 reciprocates up and down, and rotates the crankshaft 30 via the arm 31.

In the diesel engine 10 according to the present embodiment, when the crosshead 20 is located at the bottom dead center, the oil groove 2
5 and the partial oil groove 26 are formed so as not to be exposed from the guide rail 28. Thereby, the crosshead 20
Air does not enter the oil groove 25 and the partial oil groove 26 even if a part of the oil groove protrudes from the guide rail 28 toward the crankshaft 30.

Conventionally, in order to prevent air from entering the oil groove, the sliding surface 23a of the guide shoe 23 is covered by the guide rail 28 at the bottom dead center, as shown in FIG. Was needed. However, according to the configuration of the diesel engine 10 of the present embodiment, as shown in FIG. 5B, even if the crosshead 20 is located below the guide rail 28 at the bottom dead center, the oil groove 25 and the Since no air enters the partial oil groove 26, the problem of damage to the guide shoe does not occur.

As a result, as shown in FIG. 5B, the connecting rod 18 can be shortened to make the diesel engine 10 compact.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments.

In the above embodiment, the interference with the arm 31 is avoided by cutting out a part of the guide rail 28 within the rotation radius R of the arm 31. However, the crosshead 20 and the guide rail As long as the crosshead 20 can be stably supported by the contact portion 28, there is no need to provide the guide rail 28 within the turning radius R of the arm 31. In this case, the rotation radius R of the arm 31
No oil groove is formed in the portion of the sliding contact surface 23a that enters the inside.

[0019]

According to the present invention, the oil groove is formed so as not to be exposed from the guide rail when the crosshead is located at the bottom dead center. As a result, the crosshead at the bottom dead center can be positioned below the guide rail, so that the connecting rod can be shortened and the diesel engine can be made compact.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a diesel engine according to an embodiment of the present invention.

FIG. 2 is a view of the diesel engine according to the embodiment of the present invention as viewed from an axial direction.

FIG. 3 is a perspective view showing a crosshead.

FIG. 4 is an explanatory diagram illustrating an oil groove formed on a sliding contact surface of a crosshead.

FIG. 5 is a diagram showing an effect of the diesel engine according to the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Diesel engine, 12 ... Cylinder, 14 ... Piston, 16 ... Piston rod, 18 ... Connecting rod, 20 ...
Crosshead, 21: Crosshead pin, 22: Connecting plate, 23: Guide shoe, 23a: Sliding contact surface, 25:
Oil groove, 26 ... Partial oil groove, 28 ... Guide rail, 30 ...
Crankshaft, 31 Arm, 32 Base plate, 34 Frame, 35 Partition plate, 36 Jacket, 38 Tie bolt, 40 Propeller, 42 ..Thrust bearings, 44
... A longitudinal vibration damper.

Claims (2)

[Claims] 1. A diesel engine having a guide mechanism for sliding a crosshead connecting a piston and a connecting rod in a crank chamber, wherein the guide mechanism extends in a sliding direction of the crosshead. A guide rail, a guide shoe attached to the crosshead and having a sliding contact surface for sliding contact with the guide rail; and a sliding contact so as to be covered by the guide rail when the crosshead is located at the bottom dead center. A diesel engine comprising: an oil groove formed on a surface; 2. The diesel engine according to claim 1, wherein the guide rail is cut out so as not to interfere with the arm within a rotation radius of the arm of the crankshaft.