DK177740B1

DK177740B1 - Crosshead uniflow combustion engine

Info

Publication number: DK177740B1
Application number: DK201300166A
Authority: DK
Inventors: Lars Ascanius
Original assignee: Man Diesel & Turbo Deutschland
Priority date: 2013-03-22
Filing date: 2013-03-22
Publication date: 2014-05-19
Also published as: CN104061088B; CN104061088A; JP5567230B1; JP2014185634A; KR101422140B1

Abstract

The invention is concernes a crosshead uniflow combustion engine. The engine comprises a crank shaft (1) driven by a number of pistons, each of which reciprocating in a cylinder and being connected to the crank shaft (1) via a crosshead (3), and an engine structure having a bed frame (5) rotatably supporting the crank shaft (1 ), on the bed frame (5) a frame box (6) for guiding the reciprocal movement of a number of crossheads (3), and, on the frame box (6), a cylinder frame for carrying a number of cylinders . Further, the frame box (6) comprises on both sides of the crank shaft (1) a side wall (10) connected by rear transversal walls (11; 31, 34; 51) to a further number of guide walls (9; 39; 59; 79), each of which provides a guide plane (8) extending laterally along the path of the guided crosshead movement, and from each of which a transversal wall (7; 37) protrudes, which is aligned with the corresponding rear transversal wall (11; 31, 34; 51) and which connects the guide wall (9; 39; 59; 79) on the one side of the crank shaft (1) to a corresponding guide wall (9; 39; 59; 79) on the other side, wherein the rear transversal walls (11; 31, 34; 51) have, for stiffening the connection of the guide walls (9; 39; 59; 79) and the side walls (10), stiffening ribs (13; 33; 53) arranged normally to the path of the guided crosshead movement. The invention is characterized in that each guide wall (9; 39; 59; 79) has two reinforcing flank walls (12; 32; 52; 72) protruding on opposite sides of the corresponding rear transversal wall (11; 31, 34; 51) towards the corresponding side wall (10) and extending laterally along the path of crosshead movement such that everywhere along the path of crosshead movement, each guide wall (9; 39; 59; 79) and its two reinforcing flank walls (12; 32; 52; 72) form an open U-shaped cross section.

Description

-1 - DK 177740 B1

Crosshead uniflow combustion engine 5 The invention concerns a crosshead uniflow combustion engine according to the preamble of claim 1.

Such crosshead uniflow combustion engine are usually of the two stroke large diesel engine type, but sometimes also other large engines for ships or 10 powerplants, in particularly such engines which are driven by gas, could be found, which have uniflow scavenging in the engine combustion chamber or chambers and which have a crosshead configuration to connect the piston rod via a crosshead and a connection rod to the crankshaft in order to transfer transverse forces by the crosshead into the engine structure, such that the piston can 15 reciprocate in the respective cylinder without transverse forces.

In order to transfer the transverse forces via the crosshead into the engine structure, the engine structure of known crosshead uniflow combustion engines comprises a guiding structure for guiding the crosshead along the axis of 20 reciprocation of the piston. In earlier crosshead uniflow combustion engines, cf. e.g. GB 336, 929 A, the engine structure comprises a central U-shaped member forming the bearing saddle for the crankshaft and further, at the legs of the “U”, a guide rail for the crosshead. The U-shaped member has to be supported by a support structure formed all around the U-shaped member, on top of which the 25 cylinders are mounted.

In newer engines of the generic type, attemps are made to ease the manufacturing of the engine structure and the placement of the crankshaft.

30 In such engines, above a bed plate in which the crankshaft of the engine is received or which rotatably supports the crankshaft, the engine structure comprises a frame box, on top of which a cylinder frame is mounted, which carries -2- DK 177740 B1 the one or more cylinders or respectively cylinder liners of the engine. On the frame box, for each crosshead, a guide rail is formed having on both sides of the crankshaft a number of guide planes, which guides the respective crosshead along its path of reciprocating movement.

5

In such known engines of the crosshead uniflow type, two lateral guide planes are formed on each side of a crankshaft for each crosshead, wherein a guide wall having a guide plane for one crosshead and a guide plane for the neighboring crosshead is connected to a respective guide wall on the other side of the 10 crankshaft by a transversal wall extending transversally over the crankshaft and separating the two guide planes on each of the both connected guide walls.

On the backside of each of the guide walls, there is a rear transversal wall elongating the transversal wall extending across the crankshaft and thereby 15 connecting the backside of the respective guide wall with a sidewall of the frame box.

Usually, the two sidewalls of the frame box approach each other on their way from the bottom of the frame box to the top of the frame box, so that the frame box has 20 a shape in the form of an “A” in a plane extending normally to the crankshaft axis.

Thereby, the side walls form a carrier for the guide rail section of the frame box.

The carrier can further comprise a top plate portion connecting on the top of the frame box the guide walls on one side of the crankshaft with the respective side 25 wall and bottom wall portions connecting at the bottom of the frame box the guide rail section with the side wall on the respective side of the crankshaft.

In order to stiffen the connection between the guide walls on each side of the crankshaft with the respective side wall, and to stiffen the guide wall per se, 30 various proposals have been made in the art.

In conventional engines of the generic type, horizontal ribs are provided on each of -3- DK 177740 B1 0968-Cast_E_Guide_Rails the rear transversal walls connecting the respective sidewall with the respective guide wall. To say it more general, the ribs are extending in a plane perpendicular or normal to the way of the reciprocating crosshead movement. However, the disadvantage with this design is that on the gliding surface of the guide planes 5 rigid areas are formed at the placement of the ribs, while in between the ribs, the gliding surface is less rigid and therefore able to deform to a greater extent then where the ribs are. The rigid areas will result in a thinner oil film thickness and enhance the stress on the white metal of the guide shoe, that is the crosshead.

This could lead to fatigue cracks .

10

In an effort to solve this problem, a triangular design has been proposed in Japanese Patent Application No. JP 2005 113 843 A, wherein two vertical plates have been added to the backside of the guide wall such that the guide wall and the two added vertical plates have a triangular cross section. Thereby, the guide plane IS is equally stiffened along the whole running surface, such that a more unified oil film thickness is achieved. While the geometrical shape of this triangular design is suitable for welding, it is hard to build up casting cores and clean out moult material.

20 Another configuration is shown in Japanese Patent Application JP 2011 089 429 A, wherein, instead of a single guide wall, a guide wall member with a double wall is proposed, wherein the two vertical extending walls are interconnected by horizontal ribs. However, this leads to basically the same problem of an uneven oil film thickness distribution along the path of movement of the crosshead then with 25 the conventional design mentioned above.

A further proposal with a triangular design for the cross section of guide wall members of the frame box is shown in Japanese Patent Application JP 2004 003 485 A having the same drawbacks as to casting as mentioned 30 above.

In the closed triangular form of the guide wall members, it is moreover not possible -4- DK 177740 B1 to weld the three vertical extending wall members from the inside of the cross section, as the inside of the closed triangular guide wall member is not reachable.

In an attempt to overcome that problem, it is proposed in European Patent Application EP 2 236 802 A1 to don't let the backside stiffening plates at the 5 backside of the guide wall extend over the whole length of the vertical path of movement of the crosshead, but only over a short length in a region where the highest lateral forces to be transferred from the crosshead to the engine frame are expected. With this local reinforcement, it is possible to reach the inside of the closed stiffening structure on the backside of the guide wall at its top and bottom 10 portion for welding. The longer the stiffening structure is, however, the worse the interior of the closed structure is reachable over the whole length of the weld seam. Moreover, this design has the same problems as to casting as stated above in respect with the end - to - end triangular design. On the other hand, the shorter the backside stiffening structure is, the less is its effect in terms of 15 stiffening the guide planes for the crosshead guide shoe.

Starting from the above engine of the generic type with the conventional design of the frame box, it is therefore an object of the present invention to develop a crosshead uniflow combustion engine, wherein the frame box of the engine 20 structure can be produced easier and with a higher degree of freedom as to the selection of the manufacturing method, while the guide planes are stiffened to a high degree and with a high level of uniformity in the distribution of rigidness along the path of movement of the crosshead.

25 This object is achieved by the features indicated in claim 1.

According to the invention, each guide wall of the frame box has two reinforcing flank walls protruding on opposites sides of the corresponding rear transversal wall, namely the rear transversal wall connecting the guide wall with the 30 corresponding sidewall, towards the corresponding sidewall. That is, the two reinforcing flank walls protrude from the backside of the guide wall. Further, the two reinforcing flank walls extend laterally along the path of crosshead movement -5- DK 177740 B1 and not only locally at some hot spot region, such that everywhere along the path of crosshead movement, each guide wall and its two reinforces flank walls form an open U-shaped cross section in a plane arranged normally to the path of crosshead movement.

5

Advantageously, an equal stiffness of the entire gliding surface, namely the guide plane, is achieved with the inventive design of the guide wall sections of the frame box of the crosshead uniflow combustion engine. At the same time, the open U-shaped cross section is production friendly as regards the building up of casting 10 cores and cleaning out of moult material. It is also more production friendly as regards welding, if the reinforcing flank walls and/or the rear transversal wall should be welded onto the backside of the guide wall, as a weld seam could be set on both sides of each reinforcing flank wall and also on both sides of the rear transversal wall.

15

Open U-shaped cross section” means in terms of the application, that the two reinforcing flank wall surfaces facing each other are arranged in parallel, or, even more advantageously for casting and also for accessibility of the weld seam between such a surfaces and the backside of the guide wall, are arranged such 20 that the distance between the surfaces increases with the distance from the guide wall. That is, the U-shaped cross section is advantageously not only open, but opens up.

It is further advantageous, if each of the horizontal ribs extend from the rear 25 transversal wall to connect one of the both reinforcing flank walls with the rear transversal wall. The stiffening ribs arranged horizontally, or, in more general words, arranged normally to the path of the guided crosshead movement, might extend over the whole distance between the side wall and the backside of the corresponding guide wall. However, in many cases, this is not necessary and it is 30 enough, if one horizontal rib connects the rear transversal wall with the reinforcing flank wall and another horizontal rib on the other side of the rear transversal wall connects the other side of the rear transversal wall with the other reinforcing flank -6- DK 177740 B1 wall.

If at both sides of the rear transversal wall, the edge of the backside of the guide wall is separated of the horizontal rib by an opening, such opening could be 5 formed by casting in order to have a through whole for a stay bolt which extends through the frame box from the cylinder frame side to the bed frame side of the frame box. In order to mount the bed frame, the frame box and the cylinder frame together, the stay bolts might be threaded into threaded bores in the bed frame and could be secured at the cylinder frame by corresponding nuts.

10

Especially if the horizontal stiffening ribs are welded to the rear transversal wall and the corresponding reinforcing flank wall, it is further advantageous, if not only the edge between the backside of the guide wall and the rear transversal wall is separated by the opening of the horizontal rib, but the whole backside portion of 15 the guide wall between the reinforcing flank wall and the rear transversal wall, and even more preferably also the reinforcing flank wall surface facing the rear transversal wall. With that design, it is possible to avoid local stress maxima caused by welding of the stiffening rib to the guide wall. Moreover, accessibility of the weld seam between the horizontal stiffening rib and the rear transversal wall 20 and also between the stiffening rib and the reinforcing flank wall is ensured.

The mentioned configuration with an opening on both sides of the rear transversal wall is made for twin stay bolts, one on each side of each rear transversal wall. However, as the stay bolts have to be screwed into the bearing shell in the bed 25 frame in many configurations, and the bearing shell thickness is a factor which should be kept limited in order to ensure a small engine size, in some configurations, a single stay bolt at each rear transversal wall would be preferred over a twin stay bolts configuration. For this purpose, the rear transversal wall might have a tube wall segment forming the through hole for the single stay bolt.

30 That is, the rear transversal wall might have a flat wall portion extending between the side wall and the tubes portion or tube wall segment of it, while the tube portion might be arranged adjacent to the guide wall or connected by another flat DK 177740 B1 -7- wall portion of the rear transversal wall to the guide wall.

If only the through holes at the top plate portion of the frame box and the though holes at the bottom plate portion of the frame box have to be adapted to the 5 diameter of the stay bolts, the openings in the stiffening ribs can be casted and need no finishing after the casting.

Further, as the frame box might have a top plate portion and a bottom plate portion or bottom flange portion, it is understood, that the reinforcing flank walls may not 10 extent into the top plate portion or the bottom plate portion, but the extension of the two reinforcing flank walls is still substantially laterally along the whole path of crosshead movement and the term “everywhere along the path of crosshead movement” has to be understood in this sense. Moreover, in many cases, the guide walls do not extent to the very bottom of the frame box, but only to a lower 15 end somewhat above the bottom plate portion of the frame box, as the crosshead guide shoe to be supported in the guide rails starts from there to move upwards. Therefore, it has to be understood, that the path of crosshead movement might not start at the very bottom of the frame box, but somewhat above it and that the term “everywhere along the path of crosshead movement” might not include a 20 distance between the bottom of the frame box and the lower end of the guide walls.

In order to reinforce particularly hot spot regions, where the lateral forces to be transferred from the crosshead to the engine structures are particularly hight, the 25 length and/or with of the both reinforcing flank walls might vary over the height of the length of the guide planes. It might also be possible in an exceptional case to make the length of the both reinforcing flank walls shorter than the length of the corresponding guide plane, in order to only reinforce the frame box at the hot spot region.

As the open form of the cross section at the backside of the guide walls is particularly suitable for casting, the frame box as a whole or at least the frame box 30 -8- DK 177740 B1 without its top plate portion might be molded in one piece of cast steel.

However, as in crosshead uniflow combustion engines the piston bore might have dimensions like 0.26-0.50 meters, and the frame box might have corresponding 5 dimensions, it might be hard to form such huge mold forms. Therefore, the frame box might not be cast in one piece, but only guide plane members inside the frame box.

In one advantageous further development of the super ordinate measures, the 10 frame box might comprise guide plane members molded in one piece of cast steel, wherein each guide plane member consists of the transversal wall, the two guide walls connected by the transversal wall, the two reinforcing flank walls protruding from each of the two connected guide walls. As the guide plane member would have a cross section in a normal plane to the direction of crosshead movement, 15 which is everywhere open, in particular at the backside of the guide wall, it is easy to cast such guide plane member. Preferably, the one piece cast guide plane member could also comprise the rear transversal wall or at least a section of the rear transversal wall connected to each of the two connected guide walls. Further preferably the one piece cast guide plane member could also comprise the 20 stiffening ribs connecting each of the two rear transversal walls or transversal wall sections with the corresponding to reinforcing flank walls. Such guide plane members could be welded to a sidewall side section of the frame box, that is, in case that they comprise the rear transversal walls, directly to the sidewall, or, if they do only comprise sections of the rear transversal wall, to the sidewall side 25 sections of the transversal walls, or, if they do not comprise the transversal walls at all, to the transversal walls connected to the sidewalls.

In another advantageous further development, the frame box might comprise guide plane members each of which molded in one piece of cast steel, wherein 30 each guide plane member consists of the guide wall and the two reinforcing flank walls protruding from the guide wall, only, such that each guide plane member is in the form of an open U-shaped cross section everywhere along the path of -9- DK 177740 B1 crosshead movement. Each of the thus formed guide plane member might be welded to the respective transversal wall and the respective rear transversal wall and the corresponding stiffening ribs.

5 In another advantageous further development, the frame box might comprise guide plane members molded in one piece of cast steel, wherein each guide plane member consists of one of the guide walls, the two reinforcing flank walls protruding from the guide wall, a guide wall side section of the rear transversal wall connecting to the guide wall and preferably also the stiffening ribs, wherein the 10 stiffening ribs connects the guide wall side section of the rear transversal wall with the two reinforcing flank walls of the respective guide plane member. Each guide plane member is then in the form of an open E-shaped cross section everywhere along the path of crosshead movement with the exception of the positions of the stiffening ribs. Each guide plane member might then be welded to the transversal 15 wall connecting it with the corresponding guide plane member on the opposite side of the crankshaft. Also, on its backside, each guide plane member could be welded with its guide wall side section of the rear transversal wall to the side wall side section of the rear transversal wall.

20 In further advantageous further development, the guide plane members each consists of a flat metal part like a metal strip or plate, which has been bent, such that it comprises the guide wall and the two reinforcing flank walls protruding from the said guide wall. The metal part might have been provided with a gliding layer on its guide plane forming side before bending, such that also the outer surfaces 25 of the reinforcing flank walls are provided with the gliding layer afterwards. The guide plane member formed by bending is then in the form of an open U-shaped cross section everywhere along the path of crosshead movement and could be welded to the transversal wall, the rear transversal wall and the stiffening ribs.

30 In a further advantageous further development of the invention, only small units are master formed as separate pieces of cast steel or the like and that units, namely the guide walls, the transversal walls, and the reinforcing flank walls are -10- DK 177740 B1 then welded together. Also the rear transversal walls could be provided with the stiffening ribs by welding and could be welded to the corresponding guide walls and the corresponding side wall, wherein also the reinforcing flank walls could be connected to the stiffening ribs by welding.

5

In the following, preferred embodiments of the invention are explained by means of the enclosed figures.

Figure 1 shows a schematic side view of the lower and middle part of an 10 engine according to a first embodiment of the invention;

Figure 2 shows in perspective view a frame box of the engine shown in figure 1; 15 Figure 3 shows a horizontal cross section view of a guide rail structure inside a frame box according to the prior art;

Figure 4 shows a view corresponding to the view in figure 3 of another guide rail structure inside a frame box according to another prior art; 20

Figure 5 shows a view corresponding to figures 3 and 4 of a guide rail structure inside a frame box shown in figure 2;

Figure 6 shows a horizontal cross section partial view of a guide rail structure 25 according to a further embodiment of the invention;

Figure 7 shows a horizontal cross section partial view of another guide rail structure according to another embodiment of the invention; and 30 Figure 8 shows a horizontal cross section partial view of another guide rail structure according to another embodiment of the invention.

-11 - DK 177740 B1

Reference is made now to figure 1, where a crankshaft is designated by 1. The crankshaft 1 is rotatably supported inside bearings, which form parts of a machine bed or bed frame 5 of the engine structure of the shown crosshead uniflow 5 combustion engine. Not shown is a piston, which is connected over a piston rod 4, a crosshead 3 and a connecting rod 2 to the crank pin of the crankshaft 1. The crosshead 3 is guided along guide planes 8 extending on both sides of a crankshaft 1 vertically, that is in the direction of the crosshead movement, and laterally with respect to the crankshaft 1. The guide planes 8 are formed inside a 10 frame box generally designated with 6, mounted on the bed frame 5. On the frame box 6, the cylinder section or cylinder frame, which is not shown, of the engine is mounted.

The frame box 6 is shown in figure 2. It comprises two sidewalls 10, which extend 15 from the bottom of the frame box 6 upwards with decline towards each other, such that the frame box has the form of an “A” seen in the direction of the crankshaft 1. Between the side walls 10, several guide rail structures are arranged and mounted to the side walls 10, which are shown in a greater detail in figure 5. On top of the side walls 10, a top plate 16 is arranged on both sides of four vertical channels 20 enclosed by the guide rail structures and separated from each other by transversal walls 7, which form a part of the guide rail structures.

Taking now reference to figures 3 to 5, a guide rail structure according to an embodiment of the invention shown in figure 5 is compared to guide rail structures 25 of the prior art, which are shown in figures 3 and 4.

Generally, be it in the prior art or in the embodiment of the invention, each crosshead is supported by two guide planes 8", 8', 8 on each side of the crankshaft, wherein the guide planes 8", 8', 8 are formed pairwise on guide walls 30 9", 9', 9. Each guide wall 9", 9', 9 is connected by a transversal wall 7", 7', 7 extending across the crankshaft with a corresponding guide wall 9", 9', 9 on the other side of the crankshaft, wherein the transversal wall 7", 7', 7 separates the DK 177740 B1 - 12- two guide planes 8", 8', 8 on each guide wall 9", 9', 9 from each other, such that the one guide plane 8", 8', 8 is designated to one crosshead and the other guide planes 8", 8', 8 is designated to an neighboring crosshead. On the backside of each of the guide walls 9", 9', 9, that is on the side facing to the respective side 5 wall 10", 10', 10 of the frame box, a rear transversal wall 11", 11', 11, which is an elongation of the corresponding vertical extending transversal wall 7", 7', 7, connects the respective guide wall 9", 9', 9 with the corresponding side wall 10", 10', 10.

10 In so far, the guide rail structures shown in figures 3 to 5 do not differ from each other. However, there is a difference in the reinforcement for the guide walls 9", 9', 9 and their support inside the frame box, namely their support against the side walls 10", 10’, 10.

15 In the known guide rail structure shown in figure 3, guide walls 9" are supported on the backside by horizontal stiffening ribs 13" against the side walls 10", which stiffening ribs 12" are also connected to the rear transversal wall 11". This structure has the disadvantage of a higher rigidness of the guide walls 9" at the position of the horizontal ribs 13" as compared to a position, where no horizontal 20 rib 13" is. This leads to an uneven distribution of the oil film on the guide plane 8".

In order to overcome this problem, in the known guide rail structure shown in figure 4 a triangular design of the backside guide wall support is used. That is, no vertically extending supporting plates 12' are welded with their one end onto the 25 backside of the guide wall 9' and with their other end on the rear transversal wall 1T, such that, in cross section, a triangle is formed. With that design, the problem of uneven stiffness of the guide wall 9' has been overcome. However, the closed cross section of the triangle is not suitable for casting of the guide rail structure. Therefore, as shown in figure 4, the plates 12' have to be welded into their 30 positions. Counter welding on the inside of the triangular cross section is also not possible, such that the quality of the welding seam on the outside of the triangular cross section has to be ensured with some efforts as regards working time.

-13- DK 177740 B1

The guide rail structure according to the embodiment of the invention, shown in figure 5 is molded or casted in one piece together with the other guide rail 5 structures and the sidewalls 10 of the frame box 6 of cast steel. That is, the frame box 6 is cast in one piece. On the backside of each guide wall 9, two reinforcing flank walls 12 are protruding towards the respective sidewall 10. Thus the horizontal cross section in the region of the guide wall 9 has the form of an open Έ” formed by the guide wall 9, the two reinforcing flank walls 12 and, in between 10 of them, the rear transversal wall 11. Thereby, a good wall stiffness of the guide wall 9 is achieved, while the openness of the cross section allows casting, which is advantageous in terms of rigidity of the frame box 6 as a whole and terms of tolerances, which could be met.

15 Further reinforcement of the connection between the side walls 10 and the guide walls 9 is achieved by horizontal stiffening ribs 13, which connect the respective side wall 10, the respective rear transversal wall 11 and the two corresponding reinforcing flank walls 12, and therewith, only indirectly also the respective guide wall 9.

20

The stiffening ribs 13 are separated from the guide wall 9 by openings 15, which are formed already during casting and which serve as through holes for stay bolts 14, with which the cylinder frame, the frame box 6 and the bed frame 5 are mounted together. The openings 15 on the horizontal ribs are formed with a 25 greater diameter then the stay bolts 14 and only through holes 17 in the top plate 16 and through hole 18 in a bottom flange portion of the frame box 6 - see figure 2 - are sized for the stay bolts 14. Therefore, no finishing is needed for the openings 15 after casting, but only for the through holes 17 and 18.

30 If one does not have the possibility to form a large part as the whole frame box 6 constitudes in one piece by molding, one could make use of one of the alternative embodiments of the invention shown in figures 6 to 8.

-14- DK 177740 B1

In the embodiment shown in fig. 6, a guide plane member 30 consisting of a guide wall 39 with the two guide planes, the two reinforcing flank walls 32 protruding on backside of the guide wall 39 towards the side wall, a guide wall side section 34 of 5 the rear transversal wall 31, 34 and the horizontal ribs 33 is formed in one piece by molding of cast steel. The guide plane members 30 are then inserted into place inside the frame box and welded with their guild wall side section 34 of the rear transversal wall 31,34 to a sidewall side section 31 of the rear transversal wall 31, 34. On the front side, that is on the side of the guide plane, the guide plane 10 member is connected by welding to a transversal wall member forming the transversal wall 37 between one guide plane member 30 on one side of the crankshaft and another guide plane member 30 on the other side of the crankshaft.

15 In the alternative embodiment shown in fig. 7, a guide plane member 50 formed in one piece comprises only the guide wall 59 and the two reinforcing flank walls protruding in the backside of the guide wall 59. The guide plane member 50 is , formed out of a metal strip by bending the two reinforcing flank walls around 90°.

As can seen by a dotted line, before the bending, the guide plane member forming 20 metal strip has been coated with a glide coating in order to provide good gliding characteristics on its guide planes. The guide plane member 50 is welded to the transversal wall 37 and the rear transversal wall 51 and also to the horizontal stiffening ribs 53. This embodiment could be used, if one has no capacities for casting. However, the weld seams between the rear transversal walls 51 and the 25 backside of the guide wall 59 might be hard to reach, so that the embodiment shown in figure 6 could be advantageous, if one has the capacity for casting.

Another possibility to overcome the problem of the accessibility of the weld seams between the rear transversal wall 51 and the backside of the guide wall is to also 30 weld the reinforcing flank wall 72 to the guide wall 79, as can be seen in figure 8.

One can then at first weld the rear transversal wall 51 to the guide wall 79 and afterwards the two reinforcing flank walls 72 to the guide wall 79.

-15- DK 177740 B1 ln the figures, round openings are shown as through holes for the stay bolts. However, it is preferred, if the openings have a different form. One of that forms is indicated in figure 8 by dotted lines. That is, the openings 75 in the embodiment of 5 figure 8 separates the stiffening ribs 73 from the guide wall 79 and also from the surfaces facing the rear transversal wall 51 of the two reinforcing flank walls 72. Thereby, local stress maxima caused by welding could be avoided while the function of supporting the stiffening ribs, namely stiffening of the guide rail structure is still achieved.

10

In the embodiment shown in figure 6, by dotted lines the form of the preferred openings 35 is indicated. The openings 35 could be masterformed in the casting process of the guide wall members 30 in the form of proximately a quarter circle separating the edges between the guide wall 39 and the rear transversal wall 31, 15 34 of the horizontal stiffening ribs 33. The horizontal stiffening ribs 33 of the guide plane member 30 shown in figure 6 are, as compared to the embodiment shown in fig. 7 and 8, relatively short and do not connect to the respective sidewall of the frame box, but only to a sidewall side end of the guide wall side section 34 of the rear transversal wall 31, 34, which is formed in one piece with the guide plane 20 member 30.

Various modifications are thinkable without deriving from the scope of the invention.

Claims

An even-flush cross-head internal combustion engine with a crankshaft (1) driven by a plurality of pistons each reciprocating in a cylinder and connected to the crankshaft (1) via a cross head (3) and with a motor structure with a bottom frame (5) pivotally supporting the crankshaft (1) on the bottom frame (5) a support (6) for controlling the reciprocating movement of a plurality of cross heads (3), and on the support (6) a cylinder frame to support a plurality of cylinders, wherein the frame (6) on both sides of the crankshaft (1) comprises a side wall (10) connected through a transverse rear wall (11; 31; 34; 51) to a further number of guide walls (9; 39; 59; 79), each having a guide plane (8) extending laterally along the path of the controlled movement of the crosshead, and exiting from each a transverse wall (7; 37) which aligns with the corresponding transverse rear wall (11). ; 31; 34; 51) and connects the guide wall (9; 39; 59; 79) on one side of the crankshaft (1) having a corresponding guide wall (9; 39; 59; 79) on the other hand, and wherein the transverse rear walls (11; 31; 34; 51) for stiffening the connection between the guide walls (9; 39; 59; 79) and the side walls (10) have stiffening ribs (13; 33; 53) arranged at right angles to the path of the controlled crosshead motion, characterized in that each guide wall (9; 39; 59; 79) has two reinforcing flank walls (12; 32; 52; 72) projecting on opposite sides of the corresponding transverse rear wall (11; 31; 34; 51) in the direction of the associated sidewall 25 (10) and laterally along the path of the crosshead movement, each guide wall (9; 39; 59; 79) and its two reinforcing flank walls (12; 32; 52; 72. form an open, U-shaped cross-section.

Equal-flush cross-head internal combustion engine according to claim 1, characterized in that the two reinforcing flank walls (12; 32; 52; 72) facing the corresponding transverse rear wall (11; 31; 34; 51) at each control wall (9; 39; 59; 79) are arranged in parallel or such that the distance between the surfaces increases with the distance from the guide wall (9; 39; 59; 79).

A smooth-rubbed cross-head internal combustion engine according to claim 1 or 2, characterized in that each of the stiffening ribs (13; 33; 53) exits the transverse rear wall (11; 31; 34; 51) to connect one of the two reinforcements 2 DK 177740 B1 knows the flank walls (12; 32; 52; 72) with the transverse rear wall (11; 31; 34; 51), with on both sides of the transverse rear wall (11; 31; 34; 51) the rear edge of the guide wall (9; 39; 59; 79), and preferably the entire rear portion of the guide wall (9; 39; 59; 79) between the reinforcing flank wall 5 (12; 32; 52; 72) and the transverse rear wall (11; 31; 34; 51 ) and even more preferably also towards the transverse rear wall (11; 31; 34; 51) facing surface of the reinforcing flank wall, separated from the horizontal rib (13; 33; 53) by an opening (15; 35; 75) .

An evenly flushed cross-head internal combustion engine according to claim 1, 2 or 10 3, characterized in that the bottom frame (5), the frame (6) and the cylinder frame are mounted by means of stud bolts (14) extending through the frame (6) and secured in the the bottom frame (5) and is secured to the cylinder frame, each of the stiffening ribs (13; 33; 53) comprising at least one opening (15) such that on each side of each of the transverse rear walls (11; 31; 15 34; 51) at least one of the stud bolts (14) is passed through a series of overlying apertures (15), and the apertures (15) of the individual horizontal ribs (13; 33; 53) having a larger diameter than associated passage holes (17) at a top plate portion (16) and associated through holes (18) at a base plate portion of the frame (6). 20

Equal-flush cross-head internal combustion engine according to one of the preceding claims, characterized in that the length and / or width of both reinforcing flank walls (12; 32; 52; 72) vary over the height of the length of the control planes (8).

An evenly flushed cross-head internal combustion engine according to one of the preceding claims, characterized in that the frame (6) as a whole, or at least the frame without its top plate part, is molded in a piece of cast steel.

A smooth-rubbed cross-head internal combustion engine according to one of the preceding claims, characterized in that the frame comprises control plane elements molded into a piece of cast steel, each control element being composed of one of the transverse walls, the two control walls connected through the transverse wall, the two reinforcing flank walls. projecting from each of the two connected guide walls, and preferably the transverse back wall connected to each of the two connected guide walls, and more preferably the stiffening ribs connecting each of the two transverse back walls to the associated two reinforcing flank walls, each guide plane element is welded to a side wall 3 DK 177740 B1 section of the rack.

An even-flush cross-head internal combustion engine according to any one of the preceding claims 1 to 5, characterized in that the frame comprises control plane elements molded into a piece of cast steel, each control plane element consisting of one of the control walls and the two reinforcing flank walls which protrude. from the guide wall so that each guide element is in the form of an open U-shaped cross section throughout the path of cross-head movement, with each guide element being welded to the transverse wall, to the transverse rear wall and to the stiffening ribs. 10

An even-flush cross-head internal combustion engine according to any one of the preceding claims 1 to 5, characterized in that the frame comprises guide plate elements (30) molded in a piece of cast steel, each guide plane element (30) consisting of one of the guide walls (39), the two reinforcing flank walls (32) projecting from the guide wall (39), a guide wall side portion (34) of the transverse rear wall (31; 34) and the stiffening ribs (33), the stiffening ribs (33) connecting the transverse rear wall (31); 34) guide wall side section (34) with the two reinforcing flank walls (32) such that each guide plane element is in the form of an open E-shaped cross section throughout the crosshead movement path, except at the positions of the stiffening ribs (33), and each guide plate member (30) is welded to the transverse wall (37) and to the transverse rear wall (31; 34) side wall side portion (31).

An even-rinsed cross-head internal combustion engine according to any one of the preceding claims 1 to 5, characterized in that the frame comprises control plate elements (50), each control element being formed by bending a flat metal piece such that it consists of one of the control walls (59) and its two reinforcing flank walls (52) and so that each guide element (50) is in the form of an open U-shaped cross section throughout the path of crosshair wood movement, each guide member (50) being welded to the transverse wall (37), to the transverse rear wall (51) and to the stiffening ribs (53). 30

An evenly flushed cross-head internal combustion engine according to any one of the preceding claims 1 to 5, characterized in that the guide walls (79), the transverse walls (37) and the reinforcing flank walls (72) are formed as separate pieces of cast steel welded together, each of which the guide walls (79) are welded to the associated transverse back wall (51) and each of the reinforcing flank walls (72) is welded to the associated stiffening rib (73).