CYLINDER LINER FOR AN INTERNAL COMBUSTION ENGINE

Description

[0001] The invention relates to an arrangement comprising a cylinder liner, a cylinder head and a crankcase.

[0002] A cylinder liner (engl. cylinder liner) is an insert in the crankcase of a reciprocating piston engine (internal combustion engine) which forms the running surface for a piston of the reciprocating piston engine. Cylinder liners are often used because the material from which the crankcase is made does not meet the tribological requirements for a running surface for piston movement. It is therefore expedient to arrange a cylinder liner in a cylinder bore in the crankcase. There are various ways of installing a cylinder liner in the crankcase. In car engines, for example, it is usual to cast a cylinder liner into the crankcase. In larger internal combustion engines, e.g. stationary internal combustion engines for power generation, cylinder liners are detachably inserted into a cylinder bore in the crankcase.

[0003] With regard to the type of cooling, a distinction is made between "wet" and "dry" cylinder liners. Wet cylinder liners are directly surrounded by the engine's coolant. For this purpose, a gap is provided between the outer surface of the cylinder liner and the wall of the bore into which the cylinder liner is inserted. A wet cylinder liner is therefore installed with a gasket.

[0004] Dry cylinder liners, which generally have a thinner wall than wet cylinder liners, are typically shrunk into a cylinder bore of the crankcase. Heat is dissipated from the cylinder formed by the cylinder liner into the crankcase via heat conduction.

[0005] With wet cylinder liners, there are various options for installation in the crankcase mount: so-called hanging cylinder liners are inserted into the crankcase at a collar forming the upper edge of the cylinder liner. So-called mid-stop liners have a shoulder on their outer circumference in the middle of their longitudinal extension, in which they are mounted in a corresponding mount in the crankcase bore. Such a design is known, for example, from US 4,244,330 or US 5,979,374 A. With bottom-stop cylinder liners (English: bottom stop - liner), the cylinder liner is mounted on its lower side, i.e., the side facing the cylinder head. Such a design is known from US 4,385,595 or US 3,086,505. Finally, cylinder liners are also known that are vertically secured in the cylinder housing of the internal combustion engine via a collar at their upper end, i.e., the end facing the cylinder head. Such a design is known, for example, from DE 1 957 811.

[0006] Further embodiments known from the prior art are disclosed in US 5,251,578 A or EP 0 512 858 A1.

[0007] During operation, cylinder liners are exposed to high thermal and mechanical stress.

[0008] The object of the invention is to provide an arrangement of a cylinder liner and a crankcase with improved cooling.

[0009] These objects are achieved by an arrangement comprising a cylinder liner, a cylinder head and a crankcase according to claim 1. Advantageous embodiments are specified in the dependent claims.

[0010] According to the invention, an arrangement is provided comprising a cylinder liner with a collar, a cylinder head and a crankcase, wherein the cylinder liner has on its outer surface exactly one protruding flow guide device which is axially spaced from the collar and provided with at least one axial opening, wherein the cylinder liner is arranged in a cylinder bore to form a cavity between a outer surface of the cylinder liner and a wall of the cylinder bore, wherein at least one inflow channel and at least one outflow channel for a cooling medium are arranged at axially opposite ends of the cylinder bore, wherein the flow guide device is provided in the cavity axially between the at least one inflow channel and the at least one outflow channel, wherein the cylinder liner is aligned in the crankcase in such a way thatthat at least one axial opening of the above flow guide device corresponds in terms of its angular position to the position of at least one exhaust valve arranged in the cylinder head.,

[0011] By having a protruding flow guide device on its circumference, axially spaced from the collar and provided with at least one axial opening, the cooling of the cylinder liner is significantly improved. An axial opening means that the guide device has an interruption that allows flow through the guide device in a direction along a surface line (i.e., parallel to the longitudinal axis) of the cylinder liner.

[0012] It is preferably provided that the protruding flow guiding device runs in a circumferential direction of the outer surface of the cylinder liner.

[0013] The above flow guide device can, for example, be designed as a circumferential web on the cylinder liner.

[0014] The flow guide device preferably runs entirely in the circumferential direction. It would also be conceivable to design the flow guide device similar to a ring placed at an angle on the cylinder liner. However, this would be very complex to manufacture.

[0015] Preferably, the flow guiding device is designed as a web on the outer surface of the cylinder liner in such a way that the web extends in a circular ring circumferentially from the outer surface of the cylinder liner.

[0016] The above flow guide device can be designed as a sleeve or ring subsequently applied to the cylinder liner. The material for this can be metal or plastic.

[0017] Preferably, however, the protruding flow guide device is an integral component of the cylinder liner. Thus, the flow guide device can be manufactured using a turning operation.

[0018] It is preferably provided that if there is exactly one axial opening, this opening amounts to a maximum of 25% of the circumference of the above flow guiding device.

[0019] In other words, the opening extends (in the circumferential direction if the flow guide device is present) over a maximum of 90°.

[0020] The number of openings depends on the installation conditions of the cylinder liner in the crankcase. In particular, the shape and number of cooling channels leading into the gap between the cylinder liner and the crankcase are taken into account.

[0021] It is intended that if there are two openings, each of them should be a maximum of 20% of the circumference of the above flow guide device.

[0022] If there are three openings, it is intended that each of them should be a maximum of 18% of the circumference of the above flow guide device.

[0023] It is intended that if there are four openings, each of them should be a maximum of 15% of the circumference of the above flow guide device.

[0024] It is preferably provided that the sum of all axial openings amounts to a maximum of 25%, preferably a maximum of 10% of the circumference of the above flow guiding device.

[0025] It can be provided that the protruding flow guide device is arranged in the center of the cylinder liner, relative to the longitudinal extent of the cylinder liner, preferably in the upper third of the cylinder liner facing the flange. This ensures that the flow guide device influences the flow of a cooling medium to a high degree when the flow encounters zones subject to higher thermal stress – and these are usually at the level of the flange of a cylinder liner.

[0026] It is preferably provided that the cylinder liner is designed as a hanging, wet cylinder liner.

[0027] The invention is particularly suitable for application to this design principle.

[0028] Preferably, the cylinder liner can be mounted in the crankcase via its flange. Furthermore, a cavity through which a cooling medium can flow is formed between at least part of the outer surface of the cylinder liner and a wall of a cylinder liner receptacle in the crankcase.

[0029] According to the invention, the cylinder liner is arranged in a cylinder bore to form a cavity between a circumferential surface of the cylinder liner and a wall of the cylinder bore, wherein at least one inflow channel and at least one outflow channel for a cooling medium are arranged at axially opposite ends of the cylinder bore, wherein a flow guide device is provided in the cavity axially between the at least one inflow channel and the at least one outflow channel.

[0030] This outlines the installation position of a cylinder liner in a cylinder bore. The cylinder liner is cooled by a coolant flowing around it, which flows in and out of the cylinder bore at opposite ends.

[0031] Preferably, the number of axial openings in the flow guide device corresponds to the number of outflow channels. In practice, the number of openings and the number of outflow channels are thus coordinated.

[0032] According to the invention, the flow guide device is arranged on the wall of the cylinder bore.

[0033] The cylinder liner is oriented in the crankcase such that at least one axial opening of the protruding flow guide device corresponds, in terms of its angular position, to the position of at least one exhaust valve arranged in the cylinder head. The area of ​​the exhaust valve(s) (if multiple exhaust valves are provided per cylinder) is subject to high thermal stress.

[0034] The preferred arrangement ensures increased cooling in these areas. This requires the cylinder liner to be installed in the correct angular position.

[0035] It is preferably provided that the crankcase has at least one inflow channel and at least one discharge channel for guiding a cooling medium, which open into a cavity formed between a wall of a receptacle of the cylinder liner in the crankcase and at least part of the outer surface of the cylinder liner.

[0036] According to the invention, the cylinder liner is oriented in the crankcase such that the at least one axial opening of the protruding flow guide device corresponds in terms of its angular position to an inlet channel. This requires the cylinder liner to be installed in the correct position with regard to its angular position.

[0037] It is preferably provided that there is a distance between the protruding flow guide device and the wall of the cylinder liner receptacle in the crankcase.

[0038] By "clearance" here, we mean that the flow guide device is manufactured with clearance in the radial direction relative to the wall of the cylinder liner mount in the crankcase. The guide device does not serve as a mechanical guide or support for the cylinder liner in the crankcase, but is designed as a flow guide device.

[0039] The distance can, for example, be measured as a clearance of 0.5 mm.

[0040] Even if the distance between the flow guide device and the wall of the cylinder liner holder in the crankcase is favorable for installation, it is ensured that the majority of the cooling medium flow occurs through the opening(s) in the flow guide device.

[0041] The invention thus prevents so-called stagnation zones in the water jacket surrounding the cylinder liner. In stagnation zones, the flow velocity of a cooling medium is low, resulting in poor heat transfer between the cooling medium and the components adjacent to the stagnation zone.

[0042] The invention makes it possible to direct the cooling medium specifically to the zones around the cylinder liner that are subject to the highest thermal stress.

[0043] The invention is explained in more detail below with the aid of the figures, in which: Fig. 1 a cylinder liner in a first embodiment, Fig. 2 the cylinder liner from Fig. 1in an elevation, a plan view and in a cross section Fig. 3 an arrangement of a cylinder liner and a crankcase, Fig. 4 a plan view of a crankcase, Fig. 5 a cylinder liner and a crankcase in an embodiment not according to the invention Fig. 6 a schematic representation of a cylinder liner in a further embodiment Fig. 7a a plan view of a crankcase Fig. 7b diagram of temperatures on a cylinder liner in the area of ​​the collar

[0044] Figure 1 shows a cylinder liner 1 according to the invention in a first embodiment.

[0045] The cylinder liner 1 has a protruding flow guide device 5 in the form of a circumferential web on the outer surface 3. The protruding flow guide device 5 has an opening 4 in the form of an interruption of the web forming the flow guide device 5. The opening 4 is on the right side of the Figure 1 shown again as an enlarged detail. In the illustration, only one opening 4, facing the viewer, is visible. The cylinder liner 1 can, of course, have several openings 4; in the present embodiment, there are two openings 4.

[0046] In this exemplary embodiment, the flow guide device 5 is removed in the area of ​​the opening 4 down to the outer surface 3 of the cylinder liner 1. It is, of course, also conceivable to design the opening such that parts of the flow guide device 5 still protrude from the outer surface 3. It is also conceivable to design the opening(s) as bores or openings in the flow guide device 5.

[0047] The cylinder liner 1 has a collar 2, over which the cylinder liner 1 can be mounted when inserted into a cylinder bore of a crankcase of an internal combustion engine (not shown here).

[0048] Although known from descriptive geometry, a surface line ML and a circumferential direction UR are in the Figure 1 registered.

[0049] Figure 2 shows the cylinder liner 1 of Figure 1 in an elevation, a floor plan and a cross-section.

[0050] The section AA shown in the plan view is positioned such that the section runs on the left side through the protruding flow guide device 5 and on the right side through an opening 4. Since the section AA is taken along a diameter of the cylinder liner 1, it can also be seen that the openings 4 in this exemplary embodiment are not arranged exactly opposite one another on the circumference.

[0051] On the right side of the picture Figure 2 The cross-section of the cylinder liner 1 resulting from section AA can be seen. The flow guide device 5 is highlighted again as a detail.

[0052] Figure 3shows the arrangement of a cylinder liner 1 according to the invention in a crankcase 6. The cylinder liner 1 is inserted into a receptacle (the cylinder bore 8) in the crankcase 6 and rests with its collar 2 on a correspondingly designed shoulder in the crankcase 6.

[0053] A cavity 9 through which a cooling medium M can flow is formed between the outer surface 3 of the cylinder liner 1 and a wall 12 of the cylinder bore 8 in the crankcase 6.

[0054] In this cavity 9, referred to as a water jacket, a cooling medium M preferably flows in such a way that the flow direction is from below (i.e. the side facing away from the cylinder head 7) to above (i.e. the side facing the cylinder head 7).

[0055] Detail C shows how the flow guide device 5 touches the wall 12 of the cylinder bore 8 in the crankcase at one point on its circumference. At this point, the flow guide device 5 prevents a cooling medium M in the cavity 9 from flowing out of an inlet channel 10 toward a discharge channel 11. Instead, the flow is directed so that the majority of the flow passes through the opening(s) 4.

[0056] Even if the distance between the flow guide device 5 and the wall 12 of the cylinder bore 8 of the cylinder liner 1 in the crankcase 6 is favorable for installation, it is ensured that the largest part of the flow of the cooling medium M occurs through the opening 4 or the openings 4 in the flow guide device 5.

[0057] The flow direction of the cooling medium M is shown by block arrows, i.e. flowing into inlet channel 10 and flowing out of outlet channel 11.

[0058] Figure 4shows a crankcase 6 in a top view. The cut is positioned so that the openings 4 are visible.

[0059] Figure 5 shows an embodiment not according to the invention, in which the flow guide device 5 is formed as part of the crankcase 6, as highlighted in detail E. The cylinder liner 1 therefore does not have a flow guide device 5 in this example.

[0060] Figure 6 shows a simplified perspective view of a cylinder liner 1 with a protruding flow guide device 5 and an opening 4.

[0061] To illustrate the effect of the invention, flow lines of the cooling medium M are shown, as they occur when the cylinder liner 1 is installed in a crankcase 6 (not shown) between the wall of the cylinder bore 8 and the cylinder liner. This clearly shows that the flow of the cooling medium M can be effectively directed via the flow guide device 5 together with the openings 4.

[0062] Figure 7a shows a section or a plan view of an arrangement of cylinder liner 1, crankcase 6, cylinder head 7 and exhaust valves 13. A section plane is selected at the upper edge of collar 2 normal to the longitudinal axis of the cylinder liner 1. Further sections are selected so that the openings 4 in the flow guide device are visible, see also Figure 4 .

[0063] In addition to the Figure 4As explained, two exhaust valves 13 are also shown here. This illustration is not a section in the technical sense, but rather a simplified representation to illustrate the situation.

[0064] Figure 7b shows illustrative temperature profiles along the bund 2 in comparison between the prior art and the invention.

[0065] The temperature is plotted against the angle, where 360° corresponds to a full circle. The starting point of the imaginary measurement at 0° is shown in Figure 7a The abscissa in Figure 7b is therefore the development of an imaginary measuring line in the area of ​​the Federal Republic of Germany 2.

[0066] If we now consider the temperature profile for a state-of-the-art cylinder liner and crankcase arrangement, we see the solid curve designated "state of the art." It can be seen that the temperature exhibits significant peaks in the area of ​​the exhaust valves 13 (approximately at 180° and 270°).

[0067] The temperature is lowest in the area of ​​the outflow channel 11.

[0068] If we consider the temperature profile when using the invention, we see the dashed curve labeled "Invention." It can be seen that the invention results in a significantly more uniform temperature distribution across the circumference of the collar 2.

[0069] The temperature values ​​given are illustrative and can vary significantly from engine model to engine model. List of reference symbols used:

[0070] 1Cylinder liner 2Collar 3Surface of the cylinder liner 4Opening 5Protruding flow guide device 6Crankcase 7Cylinder head 8Cylinder bore 9Cavity 10Inlet port 11Outlet port 12Cylinder bore wall 8 13Exhaust valve MCooling medium URCircumferential direction MLSurface line

Claims

1. Arrangement, consisting of a cylinder liner (1) with a collar (2), a cylinder head (7), and a crankcase (6), wherein the cylinder liner (1) has on its lateral surface (3) exactly one protruding flow-guiding device (5) which is axially spaced from the collar (2) and at least one axial opening (4), wherein the cylinder liner (1) is arranged in a cylinder bore (8) to form a cavity (9) between a side surface of the cylinder liner (1) and a wall of the cylinder bore (8), wherein at least one inflow channel (10) and at least one outflow channel (11) for a coolant(M) are arranged at axially opposite ends of the cylinder bore (8), wherein the protruding flow-guiding device (5) is provided in the cavity (9) axially between the at least one inflow channel (10) and the at least one outflow channel (11), wherein the cylinder liner (1) is aligned in the crankcase (6) such that the angular position of the at least one axial opening (4) of the projecting protruding flow-guiding device (5) corresponds to the position of at least one outlet valve (13) arranged in the cylinder head (7).

2. Arrangement according to claim 1, wherein the protruding flow-guiding device (5) is arranged on the wall of the cylinder bore (8).

3. Arrangement according to claim 1 or 2, wherein the number of axial openings (4) in the protruding flow-guiding device (5) corresponds to the number of outflow channels (11).

4. Arrangement according to at least one of the preceding claims, wherein the cylinder liner (1) is mounted in the crankcase (6) via its collar (2).

5. Arrangement according to at least one of the preceding claims, wherein the cylinder liner (1) is aligned in the crankcase (6) such that the at least one axial opening (4) of the protruding flow-guiding device (5) corresponds to an inflow channel (10) with respect to its angular position.

6. Arrangement according to at least one of the preceding claims, wherein the above-mentioned protruding flow-guiding device (5) extends in a circumferential direction of the outer surface (3) of the cylinder liner (1).

7. Arrangement according to at least one of the preceding claims, characterized in that, if there is exactly one axial opening (4), it accounts for a maximum of 25% of the circumference of the protruding flow-guiding device (5).

8. Arrangement according to at least one of claims 1 to 6, characterized in that, if two openings (4) are present, these each comprise a maximum of 20% of the circumference of the protruding flow-guiding device (5).

9. Arrangement according to at least one of claims 1 to 6, characterized in that, if there are three openings (4), each of these comprises a maximum of 18% of the circumference of the protruding flow-guiding device (5).

10. Arrangement according to at least one of claims 1 to 6, characterized in that, if there are four openings (4), each of these comprises a maximum of 15% of the circumference of the protruding flow-guiding device (5).

11. Arrangement according to at least one of the preceding claims, wherein the sum of all axial openings (4) is at most 25%, preferably at most 10%, of the circumference of the protruding flow-guiding device (5).

12. Arrangement according to at least one of the preceding claims, wherein the above-mentioned protruding flow-guiding device (5) is arranged, relative to the longitudinal extension of the cylinder liner (1), in the middle of the cylinder liner (1), preferably in the upper third of the cylinder liner (1) facing the collar (2).

13. Arrangement according to at least one of the preceding claims, wherein the cylinder liner (1) is designed as a suspended wet cylinder liner (1).