DE19832844B4 - Replaceable cylinder liner for internal combustion engine with cylinder head and engine block - involves locating it's axial position within engine block by midstop, flowing coolant into passage and sealing cooling passage with interference fit between liner and block - Google Patents

Abstract

The cylinder liner (20) has a circumferential seal groove defined within it's rim (54), which is proximate a cylinder head, which forms a fire deck, a midstop below the groove and a elastomeric compounded sealing ring within the groove and contacting the engine block (38). The liner is slidably inserted in an engine block fire deck, with it's own fire deck proximate the cylinder head, while a cooling passage (44) surrounds a portion of the liner and the midstop is below the cooling passage. - The cylinder liner is located within the engine block by locating the axial position of the liner within the engine block by the midstop, flowing coolant in the cooling passage and sealing the bottom of the cooling passage with a diametrical interference fit between the interference inner diameter within the engine block and the interference outer diameter on the cylinder liner.

Description

The The invention relates to an internal combustion engine with a replaceable Cylinder liner, in particular a very efficient diesel engine with high mean induced pressures. However, the present Invention also outside of this area.

interchangeable Lead cylinder liners In internal combustion engines to considerable advantages, especially in such engines, between overhauls should have extremely long maturities. Such engines, such as Diesel engines for Trucks, can for 2 million Operating hours between overhauls be designed. At the overhaul can The cylinder liners of such engines are taken out and replaced be so that the engine block with a different set of cylinder liners is used. Furthermore spare replaceable cylinder liners during production, the need for precision machining of long holes in a block and relocate this process to a smaller, more cost effective separate cylinder liner to be machined.

Of the Constant need for more thermally efficient engines has added to it Requirements for the cylinder liners out. An increased thermal Efficiency can be improved by increasing the mean induced pressure (brake mean effective pressure) of the engine. Modern diesel engines can mean induced pressures from above Reach 2 MPa (300 psi). These have very efficient engines very high combustion temperatures. Part of the combustion energy, which is not converted to work or emitted as exhaust gas, has to be dissipated and is called heat through the walls of the Cylinder liner in the cooling system of the engine. This heat is not correct from the cylinder liner dissipated, can there are many problems. One such problem is overheating of the uppermost piston ring.

Different as the lower piston ring and the piston itself becomes the upper piston ring only limited by the engine oil cooled. In contrast to the lower piston ring is the upper piston ring directly exposed to the combustion gases. When the upper piston ring overheats, verkokt that on the inner cylinder wall with the upper piston ring in touch standing oil, what comes with a reduced lubrication. As a consequence of this the wear of the Piston ring and the cylinder liner to and a failure of the piston ring becomes more likely.

One solution to dissipate heat from the upper piston ring is to improve cooling of the cylinder liner, because a cooler cylinder liner dissipates more heat from the upper piston ring. For improved cooling interchangeable cylinder liners different proposals have been made. These proposals and ideas, which generally relate to cylinder liners, are described in the following U.S. patents:

Yet There is a need for improved cooling of cylinder liners.

The US 4,562,799 , the US 4,413,597 and the EP 0 467 469 A1 each describe a cylinder barrel socket, which has adjacent to a cylinder head an edge portion, wherein a connection between the edge portion and an engine block is formed as a press fit.

The EP 07 68 459 A1 discloses a cylinder liner, which is fixed by means of a press fit in the region of an edge portion arranged adjacent to a cylinder head in an engine block. For additional sealing, a sealing ring is provided, which is arranged in a groove formed on the edge portion.

Of the Invention is based on the object, an improved internal combustion engine specify when the wear of a sealing ring and the Wear on Parts of the engine block and the cylinder liner is minimized.

These Task is inventively by solved an internal combustion engine, having the features mentioned in claim 1.

The Cylinder liner case includes a centrally located stop the cylinder liner below the groove, the following as the center stop referred to as. An edge portion of the cylinder liner has an outer diameter on and the engine block has an inner diameter, wherein the outer diameter is designed such that it has a clearance fit in the inner diameter forms before the internal combustion engine is operated and as long as he is cold, and forms an interference fit in the inner diameter, when the combustion engine is running and while it is hot.

Further Advantages of the present invention are apparent from the following description a preferred embodiment reference is made to the accompanying schematic drawings. It shows:

1 a longitudinal section through a preferred embodiment of the present invention, which reproduces a replaceable cylinder liner arranged in an engine block,

2 a section from 1 in an enlarged view, wherein additionally a cylinder head gasket, a flame ring and a cylinder head are shown, the piston is omitted, and

3 a part of the cylinder liner 1 around an edge portion in an enlarged view.

The The present invention is particularly suitable for use in diesel engines with very high combustion temperatures and with medium induced To press above 2 MPa. The present invention is beyond in every internal combustion engine with replaceable cylinder liners can be used with advantage.

The 1 to 3 show a preferred embodiment of the present invention. In 1 is a cast, replaceable cylinder liner 20 recorded in an engine block 22 reproduced on average.

The cylinder liner 20 is typically cast and then machined on certain sliding, contact and sealing surfaces, although other machining methods can be used in the invention. In the cylinder liner 20 with their sliding diameter 26 is a piston 24 slidably added. An upper piston ring 28 which is in an upper annular groove 30 of the piston 24 is arranged, touches the sliding diameter 26 and creates a lower seal for one above the piston 24 arranged combustion chamber 31 , A pivot 32 connects the piston 24 rotatable with a connecting rod 34 , The connecting rod 34 is conventionally connected to a crankshaft, not shown here.

The cylinder liner 20 is from an upper surface 35 of the engine block 22 slidably inserted in the latter, the upper surface 35 also as the "fire deck" of the engine block 20 referred to as. The cylinder liner 20 is introduced until an existing center stop 36 a lead 38 of the engine block. The middle stop 36 is located in the middle between the upper and the un lower surface of the cylinder liner 20 relative to the central longitudinal axis X and defines the axial position of the cylinder liner 20 in the engine block 22 firmly.

Near the middle stop 36 there is an inside diameter 42 of the engine block 22 and an outer diameter 40 the cylinder liner 20 , The inner diameter 42 is about 0.15 to 0.25 mm (0.006 to 0.01 inch) smaller than the outer diameter 40 so that when inserting the cylinder liner 20 in the engine block 22 on the former a force must be exerted to the between the inside diameter 42 and the outside diameter 40 to achieve the intended interference fit. Since the force is substantially along the central axis X of the cylinder liner 20 is applied, the cylinder liner slides 20 in the engine block 22 in to the middle stop 36 the lead 38 touched. The interference fit of the outer diameter 40 in the inner diameter 42 seals the lower portion of itself between the cylinder liner 20 and the engine block 22 around the cylinder liner 20 around extending coolant channel 44 from. The press fit leads to a leak-free seal. It is not necessary to have a curable plastic material at or near the outside diameter 40 and inside diameter 42 to use to achieve a seal.

For redundancy reasons, just below the interference fit is an O-ring 46 in a groove 47 used, with "below" to be understood as in the direction of the crankshaft. Below the O-ring 46 extends an annular gap 48 between the lower part of the cylinder liner 20 and the lower part of the engine block 22 , This annular gap 48 extends along the lower part of the cylinder liner 20 to the bottom of the cylinder liner 20 near a pedestal 50 of the engine block 22 , The base 50 prevents the falling off of broken parts of the cylinder liner 20 in the crankcase of the engine. The annular gap 48 may contain oil or oil mist to the lower part of the cylinder liner 20 to help cool.

Axially near the top of the cylinder liner 20 there is a border section 54 , The edge section 54 is a thick-walled section, which is the top of the cylinder liner 20 Gives strength and stability. If the cylinder liner 20 in the engine block 22 is installed and the center stop 36 the lead 38 touches, closes the surface 56 (please refer 2 ) of the marginal section 54 approximately flush with the fire surface 35 of the engine block 22 from. The fire surface 35 and the surface 56 are referred to as a fire deck and are a cylinder head 60 adjacent. The cylinder head 60 is by means not shown screws on the engine block 22 attached and presses on a contact surface 2 against the cylinder liner 20 , whereby the latter axially between the contact surface 62 and the center stop 36 is trapped. The surface 56 and the fire surface 35 are in contact with a head gasket 58 that is between the surface 56 and the fire surface 35 and the cylinder head 60 is held in position. A fire level sealing ring 59 that is between the cylinder head 60 and the surface 56 is placed, provides a high-temperature seal around the cylinder liner 20 around.

The thick-walled edge section 54 includes an outer diameter 64 in an inner diameter 66 of the engine block 22 is included when the cylinder liner 20 in the engine block 22 is installed. Between the outside diameter 64 and the inside diameter 66 There may be a clearance fit of about 0.0025 mm (0.001 inch) diameter clearance. Under some conditions, it is also acceptable, but not required, if between the outside diameter 64 and inside diameter 66 There is a slight interference fit of 0.025 to 0.05 mm (0.001 to 0.002 inches). The manufacturing tolerances may, for example, be such that some fits of the outer diameter diameter 64 and inside diameter 66 Game fits and other fits are press fits.

Because of the possibility of a clearance fit between the inner diameter 66 and the outside diameter 64 is a circumferential sealing groove 68 in the thick-walled edge section 54 arranged. In the circumferential sealing groove 68 there is a sealing ring 70 made of elastomeric material that seals between the fire or flame plane on the fire surface 35 and the surface 56 and the coolant channel 44 manufactures. The formed in the form of an O-ring sealing ring 70 works as a primary seal as long as the engine is cold. When the engine is running and the cylinder liner 20 and the engine block 22 get hotter, the game loses itself between the outer diameter 64 and the inside diameter 66 and there is a press fit between these two diameters, whereby a seal between the coolant channel 44 and the head gasket 58 is formed. The sealing ring 70 So it works as a redundant seal during the warm-up phase of the engine. Although the sealing ring 70 According to the preferred embodiment of elastomeric material, other materials known in the art may also be used.

The thickness of the edge section 54 decreases from the outside diameter 64 along a transitional section 72 to a thinner, constant wall thickness of a section 73 the cylinder liner 20 , The transition section 72 includes a boundary of the coolant channel 44 , wherein coolant between the transition section 72 and the engine block 22 flows. Preferably, the transition between the section takes place 73 and the engine block 22 in the transition section 72 gradually, as abrupt changes in the geometry of the transition section 72 can cause a part of the coolant channel 44 near the transition section 72 is filled with steam, which means a concomitant reduction in cooling, or that it is in the coolant channel 44 near the transition section 72 cavitation occurs, causing a pitting on the cylinder liner 20 or the engine block 22 causes.

Due to the geometry of the coolant channel 44 and the inlet of the coolant flow may be the portion of the coolant channel 44 near the transition section 72 contain circulating pockets of refrigerant vapor instead of liquid coolant. The coolant flows through the coolant channel 44 and keeps acceptable cylinder liner temperatures 20 , the engine block 22 , the upper piston ring 28 , the sealing ring 70 , the head seal 58 , the fire level sealing ring 59 , the cylinder head 60 and other components upright. The coolant in the coolant channel 44 flows in a direction substantially to the central axis X of the cylinder liner 20 right-angled direction.

Approximate dimensions for the in 3 reproduced measures A to G are given in Table 1.

Table 1

The present invention includes recognizing a relationship between the dimensions of the peripheral portion 54 the cylinder liner 20 and the temperature of the upper piston ring 28 , It has been found that a reduction of the dimension A by 5 mm leads to a reduction in the temperature of the cylinder liner 20 near the top dead center position of the upper piston ring 28 of approximately 27.8 ° C (50 ° F). By decreasing the dimension A, the top of the coolant channel travels 44 passing through the transition section 72 is defined, closer to that through the fire surface 35 and the surface 56 formed fire deck and also to the top dead center position of the upper piston ring 28 approach. This will be the coolant channel 44 more effective in removing heat from the fire deck and upper piston ring 28 ,

Reducing the temperature by 27.8 ° C (50 ° F) is important for maintaining an acceptable piston ring temperature at the piston reversal point or top dead center, the point at which the piston is at 24 stops its upward movement and starts to move down. With the design of diesel engines in the direction of higher thermal efficiency and in the direction of higher induced pressures, the piston ring temperature rises at this point. Preferably, the temperature of the upper piston ring 28 kept below a temperature of about 180 ° C (350 ° F).

At about this temperature, oil begins at the upper piston ring 28 to coke, resulting in a reduced lubrication of the sliding diameter 26 and increased wear of both the sliding diameter 26 as well as the upper piston ring 28 leads. The present invention is particularly useful in diesel engines with induced mean pressures above 2 MPa (300 psi).

Decrease the dimension A and raise the transition section 72 in the direction of the upper piston ring 28 and the fire deck has the added benefit of lower sealing ring temperatures 70 and the head gasket 58 , A reduction in the height of the thick-walled edge section 54 by 5 mm reduces the temperature of the head gasket 58 in the vicinity of the cylinder liner 20 at about 17 ° C (30 ° F) and the temperature of the sealing ring 70 at approximately 10.5 ° C (19 ° F). Due to these lower temperatures, it is possible to use the head gasket 58 and the sealing ring 70 produce at a cost advantage from conventional materials. In the preferred embodiment, the sealing ring is 70 made of an ethylene copolymer elastomer and has a diameter of about 2.6 mm.

The present invention provides increased cooling of various engine components without the need for additional coolant gaps or spacer plates between the cylinder head 60 and the engine block 22 , In addition, there are no additional cooling jackets between the cylinder liner 20 and the engine block 22 required. Such cooling jackets can result in small channels that easily become clogged with dirt. Cooling jackets and bushings and intermediate coolant plates or spacer plates may also require additional seals, such as O-rings and seals, to seal the additional contact surfaces between the cylinder liner and the engine block.

Yet another advantage of lifting the transition section 72 towards the upper piston ring 28 and the fire surface 35 is that the axial extent of the coolant channel 44 , ie, from the transition section 72 to the middle stop 36 , can be reduced. A reduced axial length of the coolant channel 44 leads to an overall lighter and more compact cooling system, a simpler construction of the engine block 22 and a lighter cylinder liner 20 ,

In the preferred embodiment, the dimension A is preferably greater than about 10 mm and the dimension B is preferably greater than about 1.6 mm. The sliding diameter 26 the cylinder liner 20 is about 137 mm and the outside diameter 64 the cylinder liner 20 about 161 mm. The dimension E is preferably greater than about 23 mm. The ratio of the dimension A divided by the dimension E ranges from about 0.4 to 0.61. The dimension G is the distance from the top of the coolant channel 44 to the middle of the ring groove 30 when the piston 24 is in the top dead center position, and this distance is preferably about 8 to 9 mm.

The dimensions given in Table 1 are for a range of sliding diameters 26 from about 125 mm to about 150 mm. Outside this range, the dimensions of Table 1 must correspond to the sliding diameter 26 be scaled in a manner known to those skilled in the art. The measures outlined provide good resistance to forces caused by the combustion pressure, they offer good resistance to ripples, which can arise due to clamping forces, and they provide a long-term stability of the edge portion 54 especially in the context of sophisticated, high-efficiency and high-performance diesel engines using a cylinder liner for approximately 1.6 million km.

Claims (12)

Internal combustion engine with - a cylinder head ( 60 ) and an engine block ( 22 ), - one in the engine block ( 22 ) interchangeable cylinder liner ( 20 ), - an edge section ( 54 ) of the cylinder liner ( 20 ), which is close to the cylinder head ( 60 ) is present, - a circumferential sealing groove ( 68 ), which in the edge section ( 54 ), - a sealing ring ( 70 ), which in the circumferential sealing groove ( 68 ), and - a center stop ( 36 ) of the cylinder liner ( 20 ) located below the peripheral sealing groove ( 68 ), characterized in that the cylinder liner ( 20 ) in the engine block ( 22 ) near the center stop ( 36 ) has a Durchmesserpreßpassung, and the edge portion ( 54 ) an outer diameter ( 64 ) and the engine block ( 22 ) an inner diameter ( 66 ), wherein the outer diameter ( 64 ) is designed such that it is in the inner diameter ( 66 ) forms a clearance before the internal combustion engine is operated and while it is cold, and in the inside diameter ( 66 ) forms a press fit when the engine is operated and while hot. Internal combustion engine according to claim 1, characterized in that the sealing ring ( 70 ) consists of an elastomeric material. Internal combustion engine according to claim 1 having a surface ( 56 ) on the cylinder liner ( 20 ) and a central axis (X) of the cylinder liner ( 20 ), characterized in that the edge portion ( 54 ) from the surface ( 56 ) extends in the axial direction less than 14 mm. Internal combustion engine according to claim 3, characterized that the axial extent is less than 12 mm. Internal combustion engine according to claim 1, characterized in that the cylinder liner ( 20 ) and the engine block ( 22 ) a coolant channel ( 44 ) and the diameter interference fit a bottom of the coolant channel ( 44 ) seals. Internal combustion engine according to claim 5, characterized in that the coolant channel ( 44 ), a part of the cylinder liner ( 20 ) surrounds. Internal combustion engine according to claim 5 or 6, characterized in that a single circumferential sealing groove ( 68 ) between a surface ( 56 ) and the cooling minute channel ( 44 ) is arranged. Internal combustion engine according to claim 1, characterized that he has a diesel engine with a mean induced pressure of is more than 2 MPa (300 psi). Internal combustion engine according to one of claims 1 to 8, characterized in that it comprises a crankcase and the cylinder liner ( 20 ) at one of the edge portions ( 54 ) opposite side has a lower end, which has an outer diameter, and that the engine block ( 22 ) a socket ( 50 ) spaced apart from and below the lower end of the cylinder liner (10). 20 ) and has an inner diameter smaller than the outer diameter of the lower end. Internal combustion engine according to one of claims 1 to 9, characterized in that the sealing ring ( 70 ) the engine block ( 22 ) touched. Internal combustion engine according to one of claims 1 to 10, characterized in that the edge portion ( 54 ) a surface ( 56 ) and a fire level sealing ring ( 59 ) between the surface ( 56 ) and the cylinder head ( 60 ) is arranged. Internal combustion engine according to one of claims 1 to 11, characterized in that the cylinder liner ( 20 ) a contact surface ( 62 ) in contact with the cylinder head ( 60 ) and the cylinder head ( 60 ) at the contact surface ( 62 ) against the cylinder liner ( 20 ), so that the latter between the contact surface ( 62 ) and the center stop ( 36 ) is trapped.