JP3583972B2 - Crosshead engine with two rows of cylinders - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention comprises two rows of cylinders having mutually parallel longitudinal axes and a piston connected to the crosshead by a piston rod, the crosshead being in an engine transverse position for external guidance. The invention relates to a crosshead engine that has an inward facing (outward facing) guide surface and an inward facing (inward facing) guide surface.
[0002]
[Prior art]
Such an engine is known from Danish Patent No. 169,826, which describes various arrangements of parallel guideway pairs fastened in a fixed manner in an engine frame box, and has an outer cylinder on a crosshead of a pair of cylinders. An inwardly facing guide surface and an inwardly facing guide surface are guided by guide surfaces both outside and inside each of the crossheads. Danish Patent Publication No. 1476 / 92L describes a similar crosshead engine having two rows of vertical cylinders, the crosshead of which has a guide surface facing the outside of the crosshead and a guideway on the inside. It has an outwardly facing guide surface that slides along the surface and an inwardly facing guide surface.
[0003]
[Problems to be solved by the invention]
Current types of crosshead engines are typically very large diesel-type two-stroke engines, with engine heights of 4 to 15 meters, lengths of several meters, and widths of 2 to 7 meters, which are not uncommon.
[0004]
The large space required for such an engine desirably has a small external dimension of the engine.
[0005]
[Means for Solving the Problems]
In view of this object, the present invention is characterized in that inwardly facing (inwardly facing) guide surfaces of a pair of cylinders in two rows of adjacent cylinders abut each other. is there.
[0006]
Surprisingly, it has been found that it is possible to have the crossheads support each other, whereby the inner guide surface can be omitted completely and the distance of the cylinder in the transverse direction can be reduced. This allows for a substantially smaller engine width than the corresponding power prior art engine. Furthermore, the manufacture of the engine frame box is substantially simplified since half of the guide surface with the associated reinforcement is omitted.
[0007]
The inwardly facing guide surface can be arranged in the longitudinal center plane of the engine to provide a symmetrically configured engine. Preferably, however, the position of the inwardly facing guide surface is alternately offset in the transverse direction with respect to one side and the opposite side of the vertical longitudinal midplane of the engine. For this reason, the guide surface facing inward is arranged near the end of the crosshead pin. In the engine transverse direction, one guide surface facing inward at one end of the crosshead pin is closest to one crosshead pin, and the other guide surface facing inward at the other end of the crosshead. Is closest to the other crosshead pin.
[0008]
In one embodiment, one crosshead of the pair of cylinders has an inward facing guide surface made of steel, while the other crosshead has a white aluminum, such as tin aluminum, bronze aluminum or PTFE. The manufacture of the engine is further simplified in that it has an inward facing guide surface formed in a metal matrix of metal or another suitable bearing material. The steel surface supported by one crosshead is supported against and slides along the white metal surface, supported by the other crosshead.
[0009]
The extension distance of the inwardly facing guide surface in the engine height direction can be made extremely short, and the guide surfaces can remain in contact with each other at each position of the crosshead. The length of the guide surface is at least twice the maximum height difference in the engine height direction between the center lines in the crosshead of the cylinder pair during one revolution of the crankshaft. This relatively long distance of the engine surface ensures that the height of the guideline associated with the other crosshead pair and the centerline of the crosshead are always equal. This means that the crosshead tilts and at the same time makes a strong linear contact between the upper or lower edge of the guide surface of the inclined crosshead and the guide surface of the other crosshead. To prevent
[0010]
The cylinder can be displaced in the longitudinal direction of the engine such that the two connecting rods of the cylinder pair are pivotally supported on their respective crankpins, but for the connecting rods of the cylinder pair the engine length is reduced. Therefore, it is more suitable to be supported on the connecting crank pin.
[0011]
In one embodiment, the crosshead of the cylinder pair is at the same height when the crankpin is in its top position. Because the longitudinal axes of the cylinders are transversely offset with respect to the longitudinal center plane of the engine (which includes the longitudinal axis of the crankshaft), the plurality of pistons in a cylinder pair have When at its top position, it is not at its top dead center, and the piston of one cylinder passes its top dead center and performs its descending motion while the other piston is still on its way to its top dead center. Start. Thus, the two cylinders of the pair are staggered with respect to the ignition timing and will distribute the ignition power (the force generated by the ignition) during the ignition timing. The effect is that the area of the crankpin and main bearing need not have twice the area of a crankpin and main bearing that absorbs force from only a single cylinder. This also applies to the dimensions of the crank arm. If judged on the basis of the total power of the engine, this embodiment allows a smaller crankshaft with a smaller bearing area and a smaller arm size, and thus a shorter engine length. To
[0012]
Acting transversely, the forces transmitted between the crossheads by the inwardly facing guide surfaces are further transmitted outward to the guide surfaces mounted in the engine frame box. This installed guide surface absorbs the forces due to both crossheads, so that the inward facing guide surfaces of the cylinder pair were mounted so as not to move in the engine frame box. Preferably, the engine is designed to have a substantially smaller area than the outwardly facing guide surface that slides along the guide surface.
[0013]
In a very compact design of the engine, each of the outwardly facing guide surfaces is partially located between the associated guide surface and a support bolt located inside it. As described above, the guide surface facing outward is relatively large, and the space in the height direction is limited, so that the guide surface extends by extending between the support bolt and the guide surface. It is advantageous to have space for a larger area. A further advantage at the same time is that the support bolts are self-supporting inside the guide shoe, and for each cylinder pair only four support bolts are used to tighten together the cylinder part, engine frame box and bed plate. It is good to use.
[0014]
The short transverse distance between a pair of cylinders provided by the present invention can be used to further simplify engine design. Here, the cylinder pair has a connecting cylinder frame and thus a connecting chamber to which pressurized scavenging and supply air is supplied.
[0015]
Engines according to the present invention may be designed with more cylinders with smaller bore sizes than conventional single row crosshead engines for a given total power and a given maximum outer dimension. As such, it is particularly suitable for driving generators in power plants that can be stationary. This allows the engine to obtain a higher rotational speed (rpm) for the same total power, but is advantageous for generator design and operation.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
The invention is explained in more detail below with reference to the highly schematic drawings.
FIG. 1 shows a crosshead engine 1 with cylinders 2 arranged in two rows A, B (FIG. 3) and having mutually parallel longitudinal axes 3. Each of the cylinders has a cylinder liner 4 fastened to a top plate 6 of a cylinder frame 7 by cover studs and an actuator device which is mechanically actuated, for example by a camshaft or hydraulically driven and electronically actuated And a cylinder cover 8 having an exhaust valve 9 controlled by 10. Exhaust passages 11 from each of the exhaust valves pass exhaust gases into the coupled exhaust receivers 12 and exhaust passages from the cylinder row furthest away from the exhaust receivers allow the exhaust passages from the cylinders in the closest row to the exhaust path. Stretch between. The exhaust gas drives the turbocharger and supplies pressurized scavenging air and air supply to the scavenging air receiving unit 13. Naturally, it is also possible to use other exhaust device mechanisms such as exhaust receivers on both sides of the engine.
[0017]
Each of the cylinders further comprises a piston 14 connected to a crosshead 16 via a piston rod 15, and a connecting rod 17 is also connected to the crosshead 16. Cylinder rows A, B are arranged side by side at a short mutual distance L in the longitudinal direction of the engine (FIG. 2) corresponding to the width of the lower end of the connecting rod, whereby one of each row is provided. A cylinder pair comprising cylinders is provided with a connecting crankpin 18 on which connecting rods can be mounted side by side. Alternatively, the cylinders may be arranged without any longitudinal separation and one connecting rod may have a fork-shaped lower end gripping around the lower end of the other connecting rod. However, this has the disadvantage that the engine has two different types of connecting rods. The journal 19 of the crankshaft is supported by the main bearing of the bed plate 20.
[0018]
The cylinder frame 7 is common to the pair of cylinders, and keeps a state in which air is supplied from the scavenging air receiving unit. When the piston exposes the row of scavenging ports 21 at the lower end of the cylinder liner, air can flow into the cylinder 2. The crosshead engine is, for example, a relatively low speed two-stroke uniflow scavenging engine in the range of 60 to 400 rpm. The cylinder bore can range, for example, from 25 to 100 cm.
[0019]
The cylinder frame is located on top of the engine frame box 21 'and is mounted with the engine frame on the bed plate 20 by support bolts 22. As can be seen most clearly from FIG. 2, the frame box 21 'is separated by a transverse reinforcement or wall 23 between each pair of cylinders. A vertical guide surface 24 is mounted on this wall and reinforced at its outward facing rear by vertical struts 25. The guide surface with the associated struts extends along the entire height of the engine frame box.
[0020]
FIG. 2 shows the crosshead mounting surface 26 for the bottom flange on the piston rod 15. In the illustrated embodiment, the mounting surface 26 is located on a crosshead pin 27, which is located in the crosshead bearing at the upper end 28 of the connecting rod. Alternatively, it is possible to form a crosshead with a bearing part on the piston rod and a pin on the connecting rod.
[0021]
The crosshead pin 27 has a crosshead shoe 29 at both ends thereof, and the crosshead shoe 29 supports an inwardly facing guide surface 30 and an outwardly facing guide surface 31 at positions transverse to the engine, respectively. ing. The outwardly facing guide surface 31 is located above the guide surface 24 and can slide along the guide surface in a manner that is entirely conventional for a crosshead engine. The guide surface 31 extends into a space 32 associated between the guide surface and the support bolt.
[0022]
The inwardly facing guide surfaces 30 abut each other and can slide along with each other during rotation of the engine when the crossheads are displaced from each other in the height direction of the engine. The height difference between the crossheads is greatest when in the angular position of the crankshaft shown in FIG. The guide surfaces 30, 31 are arranged in a vertical longitudinal plane, which in the case of an inwardly facing guide surface is, as indicated by the line 33, the longitudinal central plane of the engine. Is preferred.
[0023]
FIG. 3 shows two cylinder rows A and B drawn together with the outer shape of the engine. The cylinder 2 may have, for example, a 50 cm bore, and the engine may provide approximately 26,000 kW of power to a generator unit 34 capable of generating power for the grid, for example, with 16 cylinders. Can be. For dimensional comparison, the dashed line shows the outline of an eight-cylinder crosshead engine with equivalent power and a 70 cm cylinder bore.
[0024]
For simplicity, the following description of the alternative embodiment illustrated in FIG. 4 uses the same reference numerals as described above for details of the same type. The crosshead shoe 29 is designed to be asymmetric, so that the guide surface 30 has a transverse distance s from the longitudinal center plane of the engine and at both ends of the crosshead pin to both sides of the center plane. It has been shifted. Thus, the distances c1 and c2 between the center of the guide surface 30 at one end and the other end of the crosshead pin and the center of the crosshead bearing at the upper end 28 of the connecting rod, respectively, can correspond as desired. . The guide surface 30 can be arranged, for example, such that the distances c1, c2 are equal, even when the crosshead bearings are arranged asymmetrically on the crosshead pins. As a result, the inward transverse force is uniformly distributed to the guide surfaces at both ends of the crosshead pin.
[0025]
The schematic diagram of FIG. 5 shows the relative magnitude between the transverse guidance forces between engine cycles. On the left side of the schematic, -180 ° CA indicates that the crankshaft is at an angular position where the crankpin 18 is at its lowermost position, and is where the crankpin is rotated to its top position. In an angle range of about 0 °, the piston 14 performs a compression stroke. The solid curve represents the transverse force acting on the crosshead associated with the row A cylinder, with positive values indicating outward force. On the other hand, the dashed curve b shows the corresponding force acting on the crosshead associated with the row B cylinder, and negative values indicate outward force. A dashed curve c indicates the generated force acting on the engine frame box, that is, the force absorbed by the guide surface 24. It can be seen that during the compression stroke, the forces acting on the crossheads in row A are relatively small, while the forces acting on the crossheads in row B are relatively large. During the expansion stroke, the situation is reversed. The force generated is relatively small in the region near top dead center (−60 ° to + 60 °) where the crosshead is far away from the crankshaft and the force acts on the large torque arm, and the crosshead is It can be seen that it is in an advantageous direction, acting with a small torque arm if the force on the engine frame box is relatively large to get closer to the shaft.
[0026]
From the schematic diagram, curve a shows only small negative values and curve b shows only small positive values, which means that from one crosshead to the other crosshead via the inwardly facing guide surface 30. This means that the force transmitted to the head is relatively small. In this way, the inwardly facing guide surface 30 can have a substantially smaller area than the outwardly facing guide surface 31.
[0027]
The guide surface facing inward can be designed in forms other than those described above. For example, one surface may be a flat surface as described above, and the other crosshead surface may be configured by a roller rolling on the flat surface. It is further possible that these surfaces have different areas at both ends of the crosshead pin so as to compensate for the difference in forces due to the eccentric position of the crosshead bearing on the crosshead pin. It is further possible to adjust the mass of the crosshead pin with the associated guide shoe so that the center of mass coincides with the center of the crosshead bearing. The support bolt may be at a position other than that shown, such as outside the guide surface or within the support bolt tube.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a crosshead engine according to the present invention.
FIG. 2 is a cross-sectional view taken along line II-II of FIG.
FIG. 3 is a schematic plan view of a cylinder of the engine of FIG. 1;
FIG. 4 is a cross-sectional view corresponding to FIG. 2 of another embodiment of the present invention.
FIG. 5 is a diagram showing a calculated guiding force during an engine cycle.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder 3 Parallel longitudinal axis 4 Cylinder liner 5 Cover stud 6 Top plate of cylinder frame 7 Cylinder frame 8 Cylinder cover 9 Exhaust valve 10 Actuator device 11 Exhaust passage 12 Connected exhaust receiving portion 13 Scavenging receiving device 14 Piston 15 piston Rod 16 Crosshead 17 Connecting rod 18 Connecting crankpin 19 Journal 20 Bet plate 21 ′ Engine frame box 22 Support bolt 23 Transverse reinforcement / wall 24 Vertical guide surface 25 Vertical struts 26 Mounting surface 27 Crosshead pin 28 Upper end of connecting rod 29 Crosshead shoe 30 Inwardly facing guide surface 31 Outwardly facing guide surface 32 Space 33 Line 33
Distance A, B cylinder row between the centers of the crosshead bearing of C _1, C ₂ guide surface

Claims (11)

It comprises two rows of cylinders having a mutually parallel longitudinal axis (3) and a piston (14) connected to a crosshead (16) by a piston rod, said crosshead (16) being located in a transverse engine position. In the crosshead engine (1), which holds an outwardly facing guide surface and an inwardly facing guide surface for guidance, the two rows (A, B) of adjacent cylinders (2) A crosshead engine, characterized in that the inwardly facing guide surfaces (30) of the cylinder pair abut each other. A crosshead engine according to claim 1, characterized in that the inwardly facing guide surface (30) is arranged on a longitudinal center plane (33) of the engine. 2. The crosshead engine according to claim 1, wherein the inwardly facing guide surface (30) is located near both ends of the crosshead pin (27) and inwardly at one end of the crosshead pin in a transverse direction of the engine. One facing guide surface (30) is closest to one crosshead pin, and at the other end of the crosshead pin, the other inward facing guide surface (30) is closest to the other crosshead pin. Features a crosshead engine. 4. A crosshead engine according to claim 1, wherein one of the pair of cylinders has a steel inward facing guide surface (30) and the other crosshead. A crosshead engine having an inwardly facing guide surface (30) made of a bearing material such as white metal. A crosshead engine according to any one of the preceding claims, wherein the length of the inward facing guide surface (30) is such that the length of the inwardly facing guide surface (30) in the height direction of the engine during one revolution of the crankshaft is such that the crossing of the pair of cylinders occurs. A crosshead engine characterized in that it is at least twice the maximum height difference between centerlines in the head (16). A crosshead engine according to any one of the preceding claims, characterized in that the connecting rod (17) of the cylinder pair is pivotally supported on a connecting crankpin (18). 7. A crosshead engine according to claim 1, wherein the crossheads (16) of the cylinder pairs are arranged at the same height when the crankpin (18) is at its uppermost position. Features a crosshead engine. A crosshead engine according to any one of the preceding claims, wherein the inwardly facing guide surface (30) of the pair of cylinders is mounted so as not to move in the engine frame box (21 '). A crosshead engine having an area substantially less than an outwardly facing guide surface (31) sliding along a reduced guide surface (24). 9. A crosshead engine according to claim 8, wherein each of the outwardly facing guide surfaces (31) is partly arranged between the associated guide surface (24) and a support bolt (22) arranged inside it. A crosshead engine, characterized in that: A crosshead engine according to any one of the preceding claims, wherein the cylinder pairs have a connecting cylinder frame (7). A crosshead engine (1) according to any one of the preceding claims, characterized in that it is in driving connection with a generator (34).

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