JP3867064B2 - Crosshead type large two-stroke internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a base plate with a main bearing for a crankshaft, a frame of an A-shaped crankcase mounted on the base plate, having a lateral stiffener that supports a guide surface for a crosshead. , A crosshead type large two-stroke internal combustion engine comprising a cylinder frame mounted on a frame of an A-shaped crankcase fastened to a base plate by a retaining bolt, wherein the cylinder frame includes a cylinder liner A welded structure comprising a substantially flat top plate with at least one circular hole for receiving and supporting, two outer walls substantially parallel to the crankshaft, and at least two lateral walls connecting the outer walls together. Consists of. The cylinder frame forms a support for supporting the cylinder liner, camshaft and scavenging tank.
[0002]
[Prior art]
As is well known in “K98MC Project Guide Two-Stroke Engines”, 2nd edition (1999, MBN and WV Diesel AES), the cylinder frame of a large two-stroke engine is a single unit for multiple cylinders. It is produced exclusively by iron casting as a casting or as an integral casting with a plurality of units per cylinder in the case of very large engines. The camshaft housing is cast as a unit with the cylinder frame. A substantially flat top plate with at least one circular hole for receiving and supporting the cylinder liner is mounted on the cylinder frame.
[0003]
In the case of an engine having a cylinder of 50 cm or less, the cylinder frame and the camshaft housing are cast as one unit. For engines with 60 to 70 cm cylinders, the cylinder frame and camshaft housing are typically cast into a plurality of blocks containing two cylinders. In the case of a very large engine having a cylinder of 80 cm or more, generally, the cylinder frame is cast into a plurality of blocks that accommodate only one cylinder. If the cylinder frame of a large engine is not divided into smaller units, the total weight will exceed the maximum carrying load of the crane of the engine assembly facility. Furthermore, today's casting technology has a limit on the maximum size of an object that can be cast. Manufacturing a cylinder frame by casting is a relatively inexpensive and mature technology, but dividing the cylinder frame of a large engine causes extra manufacturing costs.
[0004]
For example, to machine the top surface of the cylinder frame flat, the units are lifted one by one on a flat mirror. They are then bolted and the cylinder frame is machined. However, in the manufacturing process, the cylinder frame is assembled and disassembled before and after machining the cylinder frame itself, before and after the engine is commissioned, and when installed in a place where the engine operates, such as a ship or a power plant. Need to do. In this way, such a cylinder frame must be assembled and adjusted from a plurality of units in each of these steps, and vice versa, so that a large amount of resources is consumed in the super-large engine. Furthermore, the connections between the units of the cylinder frame must be strong and precise when assembled. Therefore, the bolted connection employed here is expensive and troublesome.
[0005]
From patent application DK1405 / 92, a crosshead type large two-stroke internal combustion engine with a cylinder frame made of welded plates is known. A thick side wall of the cylinder frame that can withstand the changing large compressive forces transmitted to the frame box and the cylinder frame by the retaining bolt is arranged directly above the outer wall of the crankcase frame. Therefore, the outer wall of the crankcase frame must also be able to withstand the large force transmitted by the above-described retaining bolt, and the thickness thereof corresponds to the thickness of the side wall. As a result, the weight of the crankcase frame is greatly increased, and consequently the weight of the entire engine is increased. Furthermore, the cylinder frame must exceed the overall width of the upper surface of the crankcase frame. This makes the cylinder frame relatively large, and additional walls extending in the longitudinal direction are required to support the top plate of the cylinder frame. Therefore, these cylinder frames are relatively heavy.
[0006]
[Problems to be solved by the invention]
In view of this background, the present invention aims to provide a crosshead type large two-stroke internal combustion engine of the type mentioned at the outset in which the above-mentioned problems have been overcome. The object is that of the A-shape mounted on the base plate according to claim 1, comprising a base plate with a main bearing for the crankshaft and a lateral stiffener supporting a guide surface for the crosshead. Achieved by a crosshead type two-stroke internal combustion engine comprising a crankcase frame and a cylinder frame mounted on a frame of an A-shaped crankcase fastened to a base plate by a retaining bolt, wherein the cylinder The frame includes a generally flat top plate having at least one circular hole for receiving and supporting a cylinder liner, two outer walls substantially parallel to the crankshaft, and at least two lateral walls connecting the side walls to each other. Comprising a welded structure with a side wall disposed substantially directly above the guide surface so as to rest on the guide surface.
[0007]
The cylinder frame can be reduced in weight by making the plate a welded structure rather than an iron-cast structure. The integrally cast cylinder frame according to the present invention for supporting a plurality of cylinder liners of a very large engine can be lifted even with the load capacity of current cranes. Further, by placing the side wall substantially directly above the guide surface so that the thick side wall of the cylinder frame rests on the guide surface of the crankcase frame, the frame box and cylinder frame are attached to the frame box and the cylinder frame by operating bolts during engine operation. The entire engine structure can be reduced in weight while maintaining the compression rigidity necessary to withstand the large changing compressive force transmitted.
[0008]
The side walls and the supporting guide surfaces may bear most of the force exerted on the engine structure by the retaining bolts, thus reducing the remaining structural parts.
[0009]
The side wall and the side wall may be welded so as to form a hollow body having a substantially rectangular cross section along the plane of the upper plate.
[0010]
The side walls may be arranged so as to incline towards each other, preferably from 0 to 10 degrees, and preferably from 2 to 10 degrees with respect to the upper plate. As a result, the distance between the upper surface of the side wall and the circular hole is reduced. Therefore, even if it receives the influence of the force transmitted with a reserve bolt, an upper board becomes difficult to bend. As a result, the stress level at the seam between the top plate and the sidewall is reduced.
[0011]
A horizontal wall may be provided between the cylinders, the hollow body having a substantially rectangular cross section may be divided, and a hollow body having a substantially square cross section for accommodating each cylinder may be formed. Thus, the upper plate is supported around each recess that receives the cylinder liner.
[0012]
In order to improve the support of the top plate around each recess, four additional walls, with a substantially square cross section, are formed so that a hollow body is formed whose cross section along the plane of the top plate is approximately octagonal. You may provide in a certain hollow body.
[0013]
The cylinder frame may further be provided with an extension wall extending in a direction substantially orthogonal from the side wall, preferably along the plane of the lateral wall, and at least one of the extension wall, one of the side walls and the reinforcing wall, A first hollow portion through which one of the two passes is formed.
[0014]
The frame of the A-shaped crankcase can also be provided with a hollow portion through which the retaining bolt passes. The second hollow part is formed by a lateral stiffener, one of the guide surfaces and a reinforcing wall.
[0015]
Suitably, the first hollow portion is positioned substantially directly above the second hollow portion so as to rest on the second hollow portion. Thus, these hollow portions are an integral part of the structure that withstands the changing large compressive forces transmitted by the retaining bolts to the frame box and cylinder frame.
[0016]
The cross sections of the first hollow part and the second hollow part are substantially triangular for practical reasons.
[0017]
The fact that the upper plate bends when the changing force exerted by the retaining bolt is transmitted from the cylinder liner to the side wall presents a potential fatigue problem of the connection between the upper plate and the side wall. One way to reduce the stress at the seam between the top plate and the side wall is that the cross section extending near the weld is preferably arc-shaped, most preferably semi-circular or semi-elliptical or similar. For example, the notch may be provided on the bottom surface of the upper plate. This largely avoids the so-called notch effect that amplifies the fatigue problem.
[0018]
The problem of fatigue of the connection between the upper plate and the side wall may be alleviated by connecting the upper plate to the side wall and / or the side wall by fillet welding. Here, the joint by fillet welding between the upper plate and the side wall is machined to provide a groove.
[0019]
The cylinder frame may further include a bottom plate made of a steel plate having a cylindrical hole for receiving the packing box.
[0020]
In order to obtain a more rigid and strong cylinder frame, the side walls and / or the side walls may be formed of steel plates, preferably rolled steel plates.
[0021]
Further objects, features, advantages and characteristics of the cylinder frame according to the invention will become apparent from the detailed description.
[0022]
In the following detailed description, details of the present invention are described with reference to exemplary embodiments illustrated in the drawings.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
In the following detailed description, the present invention will be described by means of preferred embodiments. FIG. 1 illustrates an engine according to the prior art, both larger and wider than the engine of the present invention.
[0024]
FIG. 2 shows a large 12-cylinder 2-stroke internal combustion engine 1 constructed from a base plate 7 having a main bearing for a crankshaft 22. The base plate 7 is divided into portions of an appropriate size according to available production equipment. The base plate consists of a welded tall longitudinal girder and a welded lateral girder with a cast steel bearing support intersecting it, with the cast steel bearing support. The frame 2 of the A-shaped crankcase designed for welding is mounted on a base plate 7. The crankcase frame has a stiffener in the form of a transverse plate 9 that passes between the cylinders, and the stiffener extends from the front end to the bottom of the A-shaped crankcase frame 2. Since the outer walls 10 extending in the length direction of 2 are connected to each other, the lateral rigidity of the crankcase 2 is increased.
[0025]
A vertical guide surface 13 for receiving a lateral force acting on the cross head 21 is attached to the plate wall 9 by welding, for example. Two guide surfaces 13 are disposed on both sides of the inner plate wall 9 so as to face each other in the lateral direction. The rear side of each guide surface 13 is supported by an auxiliary wall 14 extending in the vertical direction, and the auxiliary wall 14 connects the guide surface to the plate wall 9. As illustrated, the auxiliary wall 14 may be a flat plate member having an acute angle with the plate wall, but the auxiliary wall 14 having a cross section of a quarter of a circle or a quarter of an ellipse in the horizontal direction is used. You can also. That is, the auxiliary wall may extend so as to be substantially perpendicular to the plate wall 9. The guide surface 13, the auxiliary wall 14, and the plate wall 9 form a hollow portion having high torsional rigidity, and a retaining bolt is received in the hollow portion.
[0026]
As best shown in FIG. 7, the two cylinder frames 30 and 30 ′ are mounted side by side in series at the tip of the frame 2 of the A-shaped crankcase. Each cylinder frame 30, 30 ′ carries six cylinder liners 6 of the engine 1. Other configurations are naturally possible, such as an engine with 3 cylinder frames or an engine with 11 cylinders with a cylinder frame with 5 cylinders and a cylinder frame with 6 cylinders.
[0027]
The cylinder liner 6 is made of alloy cast iron. The top of the cylinder liner 6 has a hole for cooling and has a short cooling jacket. The cylinder liner 6 has a scavenging port and is perforated for cylinder lubrication. The camshaft housing 3 is mounted on one side of the cylinder frames 30 and 30 '. The scavenging tank 4 extends along the other side of the cylinder frames 30, 30 ′. The scavenging tank 4 is equipped with a turbocharger unit 8 that compresses scavenging and an exhaust sump 11 that equalizes the fluctuating pressure from the individual cylinders. The compressor of the turbocharger 8 sucks air from the engine room through an air filter, and the compressed air is cooled by a scavenging cooler that can be shared by two or more turbochargers 8. The scavenging cooler includes a steam trap that prevents the condensate from being carried with the air to the scavenging tank and the combustion chamber.
[0028]
4 and 5 show the cylinder frame 30. (The cylinder frame 30 ′ is the same as the cylinder frame 30.) The cylinder frame 30 includes two steel plates 32, 33 that extend in the length direction and form the side walls of the cylinder frames 30, 30 ′. The side walls 32, 33 are connected to each other by steel plates that extend in the lateral direction and form the front wall and the rear walls 34, 35 of the cylinder frame 30. By welding the side walls 32, 33 and the front and rear walls 34, 35, a hollow structure having a substantially rectangular cross-section is formed. The rear and front walls 34, 35 may be inclined toward each other (not shown) to reduce the weight of the structure. An auxiliary steel plate 36 extending in the lateral direction is disposed between the cylinders, and thus the rectangular cross section of the cylinder frame is divided into square portions. The auxiliary steel plate 36 in the transverse direction is welded to the side walls 32 and 33 of the cylinder frame. According to another preferred embodiment shown in FIG. 6 (a), four steel plates 37 are provided for each cylinder at an angle of approximately 45 degrees with respect to each of the side wall and the auxiliary wall. The inner cross section is generally octagonal.
[0029]
The cylinder frame can be made of ordinary steel plate or ingot. According to a preferred embodiment, the steel plate constituting the cylinder frame is a rolled steel plate. However, the upper plate may be made of any other weldable material such as cast steel.
[0030]
The upper plate 31 has a circular hole 39 for receiving and supporting the cylinder liner 6. The upper plate 31 has a side wall 32, 33 and a front wall, a steel plate forming the rear wall 34, 35, and a laterally extending auxiliary steel plate 36. Welded. A hole 38 is opened in the side wall 32 so that scavenging air can be fed into the cylinder frame 30 for each cylinder. Further, a pair of two holes 40 arranged close to each other are opened at the edge of the upper plate 31 in the longitudinal direction, and the retaining bolt 16 is received in the hole 40.
[0031]
As best shown in FIG. 5, in a preferred embodiment, the sidewalls 32, 33 are inclined toward each other. Therefore, the distance between the side walls 32 and 33 on the upper surface of the cylinder frame 30 is smaller than the distance between the walls 32 and 33 on the bottom surface. The inclination angle between the upper plate 31 and the side walls 32, 33 is preferably between about 2 degrees and about 10 degrees, but may be any angle between 0 degrees and 20 degrees. By arranging the side walls 32 and 33 so as to be inclined toward each other, the upper plate bends in response to a large changing force applied to the upper plate 31 by the cylinder liner 6 and the retaining bolt 16 during operation of the engine. Mechanical stress is reduced at the seam formed by welding between the top plate 31 and the side walls 32,33.
[0032]
In another preferred embodiment, as shown in FIGS. 8 and 9A, the side walls 32 and 33 are arranged so that the angle with the upper plate 31 is 90 degrees. Mechanical stress at the joint between the side walls formed in the welds 41 and 42 is reduced by forming the notches 43 and 44 extending along the welds. The cross sections of the notches 43 and 44 are semicircular. The cross section may be semi-elliptical.
[0033]
According to another preferred embodiment, the top plate 31 is connected to the side walls 32, 33 by fillet welds 48, as best shown in FIG. 9 (b). The joint between the fillet weld 48 and the side walls 32, 33 and the joint between the fillet weld 48 and the upper plate 31 are preferably substantially semicircular grooves 49, 49 'by machining such as grinding. To reduce the mechanical stress between each plate and fillet weld 48.
[0034]
A flange 45 extends in the horizontal direction from the bottom of the side walls 32 and 33. A vertically extending rib 46 is welded to the side wall 33 facing the camshaft housing 3. A flange 47 for mounting the camshaft housing is welded to the rib 46. The support plate 53 is welded to the end portion of the flange 47 and the side wall 33, and forms a triangular portion that receives the retaining bolt 16. In the case of an engine configured without a camshaft, the support plate 53 is welded to the wall 33 and the rib 46.
[0035]
An extension plate 50 extending in the transverse direction is welded to the side wall 32 facing the scavenging tank 4. A hole 51 is opened in the expansion plate 50 so that scavenging can pass therethrough. A plate 52 forming the upper plate of the scavenging tank 4 is welded to the expansion plate 50 and the upper plate 31. A reinforcing plate 53 extends from both sides of each expansion plate 50 toward the side wall 32 at an acute angle, and a hollow portion having a substantially triangular cross section is formed on each side of each expansion plate 50. The expansion plate 50, the reinforcing plate 53, and the side wall 32 form a hollow portion having high torsional rigidity and compression rigidity, and the hollow part receives the retaining bolt 16.
[0036]
A substantially square bottom plate 54 is welded to the inner surface of the cylinder frame 30. A circular flange 55 for receiving the piston rod packing box is welded to a corresponding hole in the center of the bottom plate 54.
[0037]
The cylinder frames 30, 30 ′ and the base plate 7 are located inside the hollow portion of the cylinder frame and the hollow portion of the frame 2 of the A-shaped crankcase. It is fixed by a set of two retaining bolts 16 arranged close to each other and extending to the bottom of the frame 2 of the crankcase. Therefore, these hollow parts function as a path for the retaining bolts and are necessary to withstand the large changing compressive forces transmitted by the retaining bolts to the frame box 2 and the cylinder frames 30, 30 'when the engine 1 is operating. Compressive stiffness is provided to the cylinder frames 30, 30 'and the A-shaped frame box 2. The lower end of the retaining bolt 16 is appropriately fixed to the screw hole in the upper part of the base plate 7. The cross sections of the hollow portions of the cylinder frames 30 and 30 ′ and the hollow portion of the crankcase frame 2 are the same, and the hollow portions of the cylinder frames 30 and 30 ′ are arranged directly above the hollow portions of the crankcase frame 2. It is preferable. As best shown in FIG. 5, the hollow portion on the camshaft housing side on the cylinder frames 30, 30 ′ may be “blocked” by a flange 47 for mounting the camshaft housing 3.
[0038]
As best shown in FIG. 7, a C-shaped plate 56 that forms each section of the scavenging tank 4 is welded between the expansion plates 50. Therefore, the internal space of the scavenging tank 4 is sealed. Therefore, the side walls 32 of the cylinder frames 30, 30 ′ also form the side walls of the scavenging tank 4. By using the side wall 32 as the side wall of both the scavenging tank 4 and the cylinder frames 30 and 30 ′, the scavenging tank 4 and the cylinder frames 30 and 30 ′ become one very small device. Thereby, the turbocharger 8 can be arranged at a low position, and therefore, the height of the entire engine 1 can be reduced by arranging the exhaust reservoir 11 at a low position, which is particularly advantageous. The exhaust reservoir 11 is mounted on a bracket 63 placed directly on the expansion plate 50. Since the turbocharger 8 and the exhaust reservoir 11 are in a relatively low position, the natural frequency of the entire exhaust reservoir increases. If the rigidity of the exhaust sump 11 is increased, the exhaust sump 11 can be divided into fewer units, so that the manufacturing cost can be reduced.
[0039]
The scavenging tank 4 is constructed from a plurality of different compartments. Each cylinder frame comprises one or two dedicated compartments 57 for mounting the turbocharger 8 and the cooler housing 58. The section 57 with the turbocharger is a welded design with a flat top plate and a hole at the bottom for receiving the air exiting the cooler. The cooler housing includes a top plate provided with a hole for receiving compressed air exiting the turbocharger, and is attached to the expansion plate by bolts or welding. The flange of the turbocharger 8 is bolted to the upper plate of the cooler housing 58. An intercooler in the form of a heat exchanger is arranged inside the cooler housing. The cooler housing may extend across multiple sections of the scavenging tank and may include and function for one or more turbochargers (not shown). Another dedicated section 60 of the scavenging tank 4 includes a suction port for the auxiliary blower 61. The cooler housing 58 can be shaped to have a diffuser portion, so that an auxiliary blower can be installed as an electric motor with an impeller that is inserted in the diffuser portion in parallel or in series with the turbocharger 8.
[0040]
The scavenging tank 4 is constructed from 12 sections. There are six standard C-shaped sections 56, three sections 57 with turbochargers, and three auxiliary blower sections 60. The scavenging tank 4 connects the two cylinder frames 30, 30 ′ by a single circular communication section 62 arranged in series between the expansion plates 50 outside the two cylinder frames 30, 30 ′. By welding the section between the expansion plates, the cylinder frame and the scavenging tank can form a rigid and stable integrated structure.
[0041]
By using a reference dimensional design for the scavenging tank 4, the individual compartments can be produced in a relatively small work area.
[0042]
An upper bracing 71 that connects the engine to the side wall (not shown) of the engine room is connected to the expansion plate 50 (see FIG. 2). The expansion plate 50 can be attached to the upper bracing at any position along the vertical expansion portion of the expansion plate. Therefore, the height of the upper bracing can be easily adjusted according to, for example, the height of the deck of the engine room.
[0043]
As best shown in FIG. 11, the cylinder frames 30 and 30 ′ on which the scavenging tank 4 is mounted have a generally rectangular cross section, which is practical for handling and machining as a unit at the time of manufacture.
[0044]
While details of the present invention have been set forth for purposes of explanation, such details are merely illustrative and one skilled in the art can make modifications without departing from the scope of the invention.
[0045]
Accordingly, while preferred embodiments of the apparatus and method have been described in connection with the developed environment, they are merely illustrative of the principles of the present invention. Other embodiments and configurations can be envisaged without departing from the spirit of the invention and the scope of the appended claims.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a conventional engine.
FIG. 2 is a cross-sectional view of the engine.
3 is a partially enlarged view, and is a cross-sectional view of the engine taken along line Ib-Ib in FIG. 1. FIG.
FIG. 4 is a perspective view of a cylinder frame.
FIG. 5 is a partial cross-sectional view of an upper portion of a cylinder frame.
FIGS. 6A and 6B are cross-sectional views of another configuration of the cylinder frame.
FIG. 7 is a perspective view of a scavenging tank mounted on a cylinder frame.
FIG. 8 is a cross-sectional view showing details of a cylinder frame and a scavenging tank.
FIG. 9 (a) shows details of a weld with a notch that reduces stress. FIG. 9 (b) shows details of the weld with a groove that reduces stress.
FIG. 10 is a more detailed cross-sectional view of another configuration of the cylinder frame and scavenging tank.
FIG. 11 is a perspective view of a cylinder frame and a scavenging tank, showing the outer shape of the combined unit.
[Brief description of symbols]
DESCRIPTION OF SYMBOLS 1 Large 12-cylinder 2-stroke internal combustion engine 2 Crankcase, crankcase frame, frame box 3 Camshaft housing 4 Scavenging tank 6 Cylinder liner 7 Base plate 8 Turbocharger 9 Horizontal plate, plate wall 10 Crankcase frame 2 Outer wall 11 extending in the length direction 13 Exhaust reservoir 13 Guide surface 14 Auxiliary wall 16 Retaining bolt 21 Cross head 22 Crankshaft 30, 30 ′ Cylinder frame 31 Upper plate 32 Side wall 33 Side wall 34 Front wall 35 Rear wall 36 Extending laterally Auxiliary steel plate 37 Steel plate 38 Side wall 32 hole 39 Circular hole 40 A set of two holes 41, 42 Welded portions 43, 44 Notched portion 45 Flange 46 Rib 47 Flange 48 Fillet welded portion 49, 49 ' Groove 50 Expansion plate 51 Hole 52 of expansion plate 50 Plate 53 forming upper plate of scavenging tank 4 Reinforcement plate 54 Bottom plate 55 Circular shape Flange 56 C-shaped only partition 61 auxiliary blowers 62 circular contact zone 63 the bracket 71 upper bracing for receiving a dedicated compartment 58 cooler housing 60 auxiliary blowers for receiving the plate 57 turbosupercharger

Claims (13)

A base plate (7) with a main bearing for the crankshaft (22) and a lateral stiffener mounted on the base plate (7) and supporting a guide plate (13) for the crosshead (21) A frame (2) of an A-shaped crankcase having (9) and a cylinder mounted on the frame (2) of the A-shaped crankcase and fixed to the base plate (7) by a retaining bolt (16) A crosshead type two-stroke internal combustion engine comprising a frame (30, 30 '),
The cylinder frame (30) includes a substantially flat top plate (31) having at least one circular hole (39) for receiving and supporting a cylinder liner (6), and two substantially parallel to the crankshaft (22). Consisting of a welded structure comprising two outer walls (32, 33) and at least two lateral walls (34, 35, 36) connecting said side walls (32, 33) to each other;
Most of the force exerted on the cylinder frame (30, 30 ′) and the frame (2) of the A-shaped crankcase by the retaining bolt (16) is used for the side walls (32, 33) and the guide plate (13). The two-stroke internal combustion engine is characterized in that the side walls (32, 33) are arranged almost directly above the guide plate so as to ride over the guide plate (13). The side wall (32, 33) and the lateral wall (34, 35, 36) are welded so as to form a hollow body having a substantially rectangular cross section along the plane of the upper plate (31). The two-stroke internal combustion engine according to claim 1 .   The two-stroke internal combustion engine according to claim 1 or 2, wherein the side walls (32, 33) are arranged so as to be inclined with respect to the upper plate (31).   A transverse wall (34, 35, 36) is provided between each cylinder, the hollow body having a substantially rectangular cross section is divided, and a hollow body having a substantially square cross section for accommodating each cylinder is formed. Item 4. The two-stroke internal combustion engine according to any one of items 1 to 3.   In order to form a hollow body having a substantially octagonal cross section along the plane of the upper plate (31), four additional walls (37) are provided in the hollow body having a substantially square cross section. The two-stroke internal combustion engine according to any one of claims 1 to 4.   The cylinder frame (30, 30 ′) further includes an extension wall (50) extending in a direction substantially perpendicular to the side walls (32, 33), and at least one of the extension walls (50) and the side wall ( 32. A two-stroke internal combustion engine according to claim 4 or 5, characterized in that a first hollow part through which one of said retaining bolts (16) passes is formed by one of the reinforcing walls (53). organ.   At least one of the lateral stiffeners (9), one of the guide plates (13) and the reinforcing wall (14) form a second hollow portion through which one of the retaining bolts (16) passes. 7. A two-stroke internal combustion engine according to claim 6, wherein   8. The two-stroke internal combustion engine according to claim 7, wherein the first hollow portion is positioned substantially directly above the second hollow portion so as to be placed on the second hollow portion.   9. The two-stroke internal combustion engine according to claim 6, wherein a cross section of the first hollow portion and the second hollow portion is substantially triangular.   The upper plate (31) is connected to the side wall (32, 33) and / or the lateral wall (34, 35, 36) in the welded portion (42), and a notch (43) is formed on the bottom surface of the upper plate (31). 44), and the cross section of the notch (43, 44) is arc-shaped, semi-circular or semi-elliptical in the vicinity of the weld (42). A two-stroke internal combustion engine according to claim 1.   The upper plate (31) is connected to the side wall (32, 33) and / or the lateral wall (34, 35, 36) by fillet welding, where a seam by fillet welding between the upper plate and the side wall is provided. 11. The two-stroke internal combustion engine according to claim 1, further comprising a groove for performing mechanical processing to reduce mechanical stress.   The bottom plate (54) for receiving a packing box, further comprising a bottom plate (54) comprising a plate with a cylindrical hole (55). Stroke internal combustion engine.   The two-stroke internal combustion engine according to any one of claims 1 to 12, wherein the side walls (32, 33) and / or the lateral walls (34, 35, 36) are formed of steel plates.

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