GB2364549A

GB2364549A - I.c. engine with replaceable cylinder liner

Info

Publication number: GB2364549A
Application number: GB0125343A
Authority: GB
Inventors: Abby J Dawkins; Kristopher R Bare; Daniel E Kirtley; Carol L Corbeels; Andrew P Perr
Original assignee: Cummins Engine Co Inc
Current assignee: Cummins Inc
Priority date: 1997-07-21
Filing date: 1998-07-20
Publication date: 2002-01-30
Anticipated expiration: 2018-07-20
Also published as: GB2364549B; GB0125343D0; GB2364548A; GB2364548B; GB0125341D0

Abstract

The position of the replaceable cylinder liner 20 within the block 22 is established by a midstop 36 contacting a block ledge 38 so that the liner 20 is clamped with axial compression between the cylinder head (60, fig.2) and the midstop 36. A diametral interference fit below the midstop 36 seals the bottom end of a cooling passage 44 that extends around the liner 20. The top end of the cooling passage 44 is sealed by an O-ring in a groove in a thickened rim section 54 of the liner which, only when the engine has warmed up, is a diametral interference fit with the engine block. The top of the cooling passage 44 is close to the TDC position of the top piston ring 28 and reduces the temperature of that ring.

Description

2364549 "REPLACEABLE CYLINDER LINER AND A METHOD.

FOR LOCATING AND SEALING IT WITHIN AN I.C. ENGINE BLOCK BACKGROUND OF THE INVENTION

This invention relates to replaceable cylinder liners for internal combustion engines, including very efficient 5 diesel engines with high brake mean effective pressures.

However, certain applications for the present invention may be outside of this field.

Replaceable cylinder liners provide significant advantages to internal combustion engines, especially those 10 engines intended to have extremely long periods of time between overhauls. Engines such as truck diesel engines may be designed for two million hours of usage between.

overhauls. At the time of overhaul, the cylinder'liners of such engines can be removed and replaced and the engine 15 block reused with another set of liners. Further, at the time of manufacturing, replaceable liners eliminate the need for precision finishing of long bores in a block, shifting that process to a smaller, more economical operation on an individual liner.

-20 The continuing need for more thermally efficient engines has placed additional demands on the cylinder liner.

Increased thermal efficiency can be achieved by increasing the brake mean effective pressure (BMEP) of the engine.

Advanced diesel engines are capable of BMEP in excess of 300 25 psi (2Mra). These very efficient engines have very high combustion temperatures. A portion of the combustion energy not converted into work or expelled as exhaust gas must be dissipated, and a portion of this energy is dissipated as heat conducted through the walls of the cylinder liner and 30 into the cooling system. If this heat is not properly removed from the cylinder liner, there can be numerous problems. One such problem involves overheating of the top piston ring.

Unlike the bottom piston ring and the piston itself, the 5 top piston ring receives only limited cooling from the engine oil supply. Unlike the bottom ring, the top piston ring is directly exposed to combustion gases. If the top piston ring overheats, oil in contact with the ring from the cylinder wall inner diameter will be converted to coke, with 10 an accompanying loss of lubrication. Ring and liner wear will be accelerated as a result, and ring failure made more likely.

One method of removing heat from the top piston ring involves improved cooling of the cylinder liner. A cooler 15 cylinder liner will conduct more heat away from the top piston ring. Various ideas have been proposed for improved cooling of replaceable cylinder liners. These ideas, as well as ideas generally relating to cylinder liners, can be found in the following U.S. Patents:

-20 Patent No. Patentee Issue Date 4,244,330 Baugh et al. 1/13/81 4,305,348 Martin 12/15/81 4,616,603 Kubis et al. 10/14/86 4,638,769 Ballheimer 1/27/87 25 4,867,118 Kubis et al. 9/19/89 5,048,468 Broughton et al. 9/17/91 5,150,668 Bock 9/29/92 5,299,538 Kennedy 4/5/94 5,343,837 Ward et al. 9/6/94 30 5,575,251 Bock 11/19/96 There is a continuing need for improved cooling of cylinder liners. The present invention provides a novel and unobvious apparatus and method for improved cooling of cylinder liners.

SUMMARY OF THE INVENTION

One aspect of the present invention provides a replaceable cylinder liner for an internal combustion engine with a cylinder head and an engine block. The cylinder 5 liner includes a rim section of the liner proximate the cylinder head, a circumferential seal groove defined within the rim section, a seal ring located within the groove, and a mid stop of the liner below the groove.

Another aspect of the present invention provides a 10 method for locating and sealing a replaceable cylinder liner within an engine.block of an internal combustion engine. The method includes receiving a replaceable cylinder liner within an engine block, locating the axial position of the cylinder liner within the engine block by a mid stop, 15 flowing coolant in a cooling passage between the liner and the block, and sealing the bottom of the cooling passage with a diametral interference fit between the cylinder liner and 'the engine block.

One object of the present invention is to provide an 20 improved replaceable cylinder liner for an internal combustion engine.

Related objects of the present invention will be apparent from the description of the preferred embodiment.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational, cross sectional illustration of the preferred embodiment of the present invention, showing a replaceable cylinder liner within an 5 engine block.

FIG. 2 is a partial, enlarged front elevational view of a portion of the FIG. 1 liner without a piston, but including a head gasket, fire ring, and cylinder head.

FIG. 3 is a partial, front elevational view of a portion 10 of the liner of FIG. 1 in the vicinity of the rim section.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific 5 language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as 10 illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

The preferred embodiment of the present invention is shown in FIGS. 1-3. FIG. 1 is a cross-sectional view 15 showing cast replaceable cylinder liner 20 as received within engine- block 22. The present invention is useful with diesel engines of yery high combustion temperatures of the variety having brake mean effective pressures (BMEP) in excess of 300 Psi (2MPa). The present invention is also useful 20 generally in any internal combustion engine with replaceable cylinder liners. Liner 20 is typically cast with subsequent machining of certain sliding, contact, and sealing surfaces, although the present invention contemplates other methods of fabrication as well.

25 A piston 24 is slidably received within piston sliding diameter 26 of liner 20. Top piston ring 28 located within top ring groove 30 contacts diameter 26, and provides a lower seal for combustion chamber 31. Wrist pin 32 rotatably connects piston 24 to connecting rod 34. Rod 34 30 is connected to a crankshaft in a conventional manner.

Liner 20 is slidably inserted within block 22- from top sur-":ace 35 of block 22, surface 35 also being called the fire deck of block 22. Liner 20 is inserted until liner midstop 36 contacts block ledge 38. Midstop 36 is at a position intermediate the top and bottom surfaces of liner 20, midway along centerline axis X. Midstop 36 establishes the axial position of liner 20 within block 22. Located 5 proximate to midstop 36 is interference inner diameter 42 of block 22 and interference outer diameter 40 of liner 20.

Inner diameter 42 is about.15 to.25 millimeters (.006-.010 inches) smaller than outer diameter 40. As liner 20 is inserted within block 22, force must be applied to liner 20 10 to overcome the interference fit designed between inner diameter 42 and outer diameter 40. As the force is applied generally about centerline X of liner 20, liner 20 slides within block 22 until midstop 36 contacts ledge 38.

The interference fit of diameter 40 within diameter 42 15 seals the bottom portion of a coolant passage 44 between liner 20 and block 22 that extends around liner 20. This interference fit results in a leak-tight seal. It is not necessary to use a settable plastic material on or near diameters 40 and 42 to provide a seal. A redundant seal is 20 accomplished with o-ring 46 inserted within groove 47 just below the interference fit, the term below indicating in the direction of the crankshaft. Extending beneath O-ring 46 is clearance annulus 48 between the bottom of liner 20 and the bottom of block 22. This clearance annulus extends along 25 the bottom length of liner 20 to the bottom of liner 20 proXimate bottom shelf 50 of block 22. Shelf 50 is useful in preventing cracked portions of liner 20 from dropping within the engine crankcase. Annulus 48 may contain oil or oil mist helping to cool the bottom portion of liner 20.

30 Located axially near the top of liner 20 is a rim section 54. Rim section 54 is a thick-walled section that provides strength and'stability to the top portion of liner 20. As liner 20 is installed in block 22 and midstop 36 contacts ledge 38, top surface 56 (see FIG. 2) of rim 35 section 54 becomes approximately.flush with top surface 35 of block 22. Top surfaces 35 and 56 are referred to as the fire deck and are proximate cylinder h'ead 60. Cylinder head is attached to block 22 by bolts (not shown). Head 60 pu shes against liner 20 at contact surface 62, clamping 5 liner 20 in axial compression between surface 62 and midstop 36. Both top surfaces 56 and 35 are in contact with head gasket 58. Head gasket 58 is held in place between top surfaces 56 and 35 and cylinder head 60. A fire deck seal ring 59 which is located between head 60 and surface 56 10 provides a high temperature seal around liner 20.

Thick-walled section 54 includes first outer diameter 64 which is contained within first inner diameter 66 of block 22 when liner 20 is installed in block 22. There may be a clearance fit of approximately 0.001 inch diametral 15 clearance between outer diameter 64 and first inner diameter 66. It is also acceptable but not necessary that under some circumstances there is a light interference fit of.025 to millimeters (.001 to.002 inches) between diameters 64 and 66. For example, production tolerances may be such that 20 some fits of diameters.64 and 66 are clearance fits, and others fits are interference fits.

Because of the possibility of a clearance fit between first inner diameter 66 and first outer diameter 64, a circumferential seal groove 68 is located within 25 thick-walled section 54. Located within groove 68 is elastomeric sealing ring 70, which provides a seal from the fire deck at top surface 35 and 56 to coolant passage 44.

O-ring 70 functions as a primary seal when the engine is cold. As the engine is operated and liner 20 and block 22 30 become hotter, clearance between first outer diameter 64 and first inner diameter 66 is lost, and diameter 64 becomes an interference fit within diameter 66. As diameters 66 and 64 come into contact, a seal between cooling passage 44 and head gasket 58 is formed. O-ring 70 functions as a 35 redundant seal when the engine is warmed up. Although seal ring 70 is elastomeric in the preferred embodiment, other materials known in the art may be substituted.

The thickness of rim section 54 reduces from the first outer diameter 64 through a transition section 72 to a 5 thinner, constant thickness wall section 73 of liner 20. Transition section 72 includes a boundary of coolant passage 44, with coolant flowing between section 72 and block 22. It is preferable that section 72 smoothly transition from wall section 73 toward engine block 22. Abrupt changes in 10 the geometry of section 72 could result in a portion of cooling passage 44 being filled with,vapor in the vicinity of section 72 with subsequent reduction in cooling, or could result in cavitation within passage 44 in the vicinity of section 72 with subsequent pitting damage to liner 20 or 15 block 22.

Because of the geometry of cooling passage and the entry point for coolant flow, the portion of cooling passage 44 proximate to transition section 72 may contain circulating pockets of coolant vapor rather than liquid phase coolant.

20 Coolant flows through coolant passage 44 and maintains acceptable temperatures for liner 20, block 22, piston ring 28, o-ring 70, head gasket 58, fire deck seal 59, and cylinder head 60, as well as for other components. Coolant in passage 44 flows in a direction approximately 25 perpendicular to the centerline axis X of liner 20.

Approximate dimensions for some aspects of the present invention (see FIG. 3) are given in Table 1.

TABLE 1

Dimension Minimum Maximum 30 millimeters millimeters A 10 14 B 1.6 5.5 C 4.3 4.5 D 2.0 2.2 35 E 23 24 F 3.6 4.4 G 7.5 9.5 The present invention includes the discovery of a relationship between the dimensions of the rim section of liner 20 and the temperature of top piston ring 28. It has been found that a five millimeter reduction in dimension A 5 results in a reduction of about 50OF (280C) in the temperature of liner 20 adjacent the location of the top dead center position of piston ring 28. As dimension A is reduced, the top of coolant passage 44, which is defined by transition section 72, moves closer to fire decks 35 and 58 10 and also to the top dead center position of top piston ring 28. Coolant passage 44 becomes more efficient at removing heat from fire deck 35 and 58 and ring 28.

The 50OF (280C) reduction is important in maintaining an acceptable ring temperature at piston reversal or top dead 15 center, the position at which piston 24 stops moving.upward and begins moving downward. As diesel engines are designed for increased levels of thermal efficiency and brake mean effective pressure (BMEP), ring temperature at this position increases. It is preferrable to maintain top ring 20 temperature below about 350OF (1800C). At about this temperature, oil on ring 28 will decompose into coke, resulting in decreased lubrication to sliding diameter 26 and increased wear of both diameter 26 and ring 28. The present invention is especially useful in diesel engines 25 with BMEP in excess of 300 psi (2MPa).

Decreasing dimension A and raising transition section 72 toward ring 28 and fire deck 56 also results in the additional benefits of lower temperatures for O-ring 70 and head gasket 58. A five millimeter reduction in the height 30 of thick-walled section 54 reduces the temperature of gasket 58 in the vicinity of liner 20 by about300F (170C), and reduces the temperature of seal ring 70 by about 190F (110C).

As a result of these lower temperatures, it is possible for gasket 58 and seal ring 70 to be constructed from conventional materials with subsequent cost savings. In the preferred embodiment, O-ring 70 is fabricated from an ethylene copolymer elastomer and has a cross sectional diameter of about 2.6 millimeters.

5 The present invention provides increased cooling to various components of the engine without the need for additional cooling spacer decks or spacer plates between head 60 and block 22. Also, there is no need for additional cooling sleeves between liner 20 and block 22. Such cooling 10 sleeves may create small passages which can become plugged with debris. Cooling sleeves or spacer decks or plates may also require additional sealing features, such as o-rings and gaskets, to seal additional liner and block interfaces.

Yet another benefit of raising transition section 72 15 toward ring 28 and fire deck 35 is that the axial length of cooling passage 44, from section 72 to midstop 36, may also be reduced. A reduction in the length of passage 44 results in an overall lighter and more compact cooling system, a simpler design of block 22, and a lighter liner 20.

20 In the preferred embodiment, dimension A is preferably larger than about ten millimeters and dimension B is preferably larger than about 1.6 millimeters. Piston sliding diameter 26 of liner 20 is about 137 millimeters.

First outer diameter 64 of liner 20 is about 161 25 millimeters. Dimension E is preferably larger than about 23 millimeters. The aspect ratio of dimension A divided by dimension E ranges from about 0.4 to 0.61. Dimension G is the distance from the top of cooling passage 44 to the center of ring groove 30 when piston 24 is at the top dead 30 center position, and is preferably about 8 to 9 millimeters.

The dimensions of Table 1 are useful for a range of piston sliding diameters 26 from about 125 millimeters to about 150 millimeters. Beyond that range, the dimensions of Table 1 woul-d be scaled with diameter 26 in a manner known 35 to those of ordinary skill in the art. In this way the present invention maintains adequate strength from combustion pressure loads, resistance to waviness from clamping loads, and long term stability for rim section 54, especially as applied to advanced, high efficiency, high 5 performance diesel engines that use a cylinder liner for about one million miles.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive

10 in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the scope of protection as claimed in the claims are desired to be protected.

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Claims

1. An apparatus comprising:

0 an internal combustion engine including a cylinder head and an engine block; a replaceable cylinder liner received within said engine block; a rim section of said cylinder liner proximate said cylinder head; a midstop of said liner, wherein said cylinder liner has a first interference diametral fit within said engine block proximate to said midstop, said rim section has an outer diameter, said engine block has an inner diameter, and said outer diameter is configured and arranged to be a clearance fit within said inner diameter before said engine is operated and when said en-ine is cold and a second interference fit within said inner diameter after said en-ine is operated and when said engine is hot.

2. A method for retaining a replaceable cylinder liner within an engine block of an 0 internal combustion enaine, said methcd comprising:

C CP receiving a replaceable cylinder liner having a rim section within an engine block; r.7 t flowin- coolant in a cooling passage between the liner and the block; 0 0 sealin- the bottom of the cooling passage with a first interferenc 0 e fit between the cylinder liner and the engine block proximate the midstop; and 0 sealing the top of the cooling passage with a second interference between the rim 0 4:1 section and the engine block.

3. An apparatus, comprising:

an internal combustion engine including a cylinder head and an engine block; a replaceable cylinder liner received within said engine block; a coolin- passage surrounding a portion of said cylinder liner; and 1 0 a midstop below said cooling passage, a portion of said cylinder liner proximate said midstop being in a first diarnetral interference fit within said engine block; C wherein the first diarnetral interference fit seals said coolin- passage proximate said midstop, said cylinder liner includes a rim section proximate said cylinder head, said rim section has an outer diameter, said engine block has an inner diameter, and said outer diameter is configured and arranged to be a clearance fit within said inner diameter when said engine is cold and a second interference fit within said inner diameter when said engine is hot.

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4. An apparatus comprising:

an internal combustion en(zine including a cylinder head and an engine block:

a replaceable cylinder liner received within said engine block.

a rim section of said cylinder liner proximate said cylinder head.

a circumferential seal groove defined within said rim section:

a sealing ring assembled within said groove: and a midstop ofsaid liner below said groove:

wherein said cylinder liner has an interference diametral fit within said en-gine block proximate to said midstop.

5. The invention of claim 4 wherein there is only one said circumferential seal groove within said rim section.

6 The invention of claim 4 wherein said seal ring contacts the engine block.

7. The invention of claim 4 wherein said seal ring is made from an elastomeric compound.

8. The invention of claim 4 which further comprises a f.i.re. deck.-o.f. said-. cyLinder- liner- a-nd an axis of said cylinder liner, wherein said rim section extends for an axial length of less than 14 millimeters from said fire deck.

9. The invention of claim 7 wherein the axial length is less than 12 millimeters.

10. The invention of claIM4 wherein said cylinder liner and said engine block define a cooling passage therebetween, and the Interference diametral fit seals the cooling passage.

11. The invention of claim 4 wherein the internal combustion engine is a diesel engine with a brake mean effective pressure greater than 300 psi (2MPa).

I 12 An apparatus. comprising:

an internal combustion en2ine includina a cviinder head and an engine block:

a replaceable cylinder liner received within said engine block. a portion of said cylinder liner proximate said midstop being in a diametral interference fit - within said engine block; a fire deck of said cylinder liner proximate said cylinder head, a cooling passage surrounding a portion of said cylinder liner: and a midstop below said cooling passage, wherein said cooling passage is less than 14 millimetres from said fire deck, and the interference fit seals said cooling passage proximate said midstop.

13. The invention of claim 12 wherein the engine block includes a fire deck proximate the cylinder head.

14. The invention of claim 12which further comprises a single seal groove between said fire deck and said cooling passage 15. The invention Of claim 14 which further comprises an elastomeric o- ring within said seal groove.

1-6. The invention of claim 14 wherein said cooling passage is less than than 12 millimeters from said fire deck.

17. The invention of claim 16 wherein the internal combustion engine is a diesel engine with a b rake mean effective pressure greater than 300 Psi (2MPa).

18. The invention of clain'12wherein said interference fit includes an interference inner diameter within the block and an inEerference outer diameter on said cylinder liner, said interference inner diameter and said interference outer diameter cooperating in a diametral interference fit.

19. A method for locating and sealing a replaceable cylinder liner within an en-szine block of an internal combustion enRine, said method comprising:

receiving a replaceable cylinder liner within an enizine block establishin the axial position of the cylinder liner within the -Ingine block by a midstop; flowinc, coolant in a cooling passage between the liner and the block. and sealing the bottom of Elie cooling passage with a djametral interference fit between the cvlinder liner and the engine block proximate the midstop.

20. The method of claim 19 which further comprises sealing the top of the cooling passage with an elastomeric o-ring.

21. The method of claim 20 which further comprises sealing below the diametral interference fit with an elastomeric o-ring.

22. The method of claim 21 wherein the internal combustion engine is a diesel engine with brake mean effective pressure greater than 300 psi (2MPa).

23. The method of claim 21 wherein said flowing of coolant occurs within the cooling passa4e less than 14 millimeters from the fire deck of the block.

lameter s Id 24. The apparatus ot claim 4 wherein said rim section has an outer di.. a cnizine block has an inner diameter. and said outer diameter is configured and arranged to be a clearance fit within said inner diameter before said engine is operated and said engine is cold and an interference fit within said inner diameter after said engine is operated and said engine is hot.

25. The apparatus of claim 4 wherein said rim section includes a top surface, and which further comprises a seal ring located between said top surface and said cylinder head.

26. The apparatus of claim 4 wherein said engine includes a crankcase, said cylinder liner has a bottom end opposite of said rim section, the bottom end havinc, an outer diameter, said engine block includes a shelf spaced apart and spaced below the bottom 5 end of said cylinder liner, said shelf having an inner diameter less than the outer diameter of the bottom end, said shelf being configured and arranged to prevent portions of said liner from dropping within said crankcase.

27. The apparatus of clairP12 wherein said engine includes a crankcase, said cylinder 10 liner has a bottom end opposite of said fire deck, the bottom end having an outer diameter, said engine block includes a shelf spaced apart and spaced below the bottom end of said cylinder liner, said shelf having an inner diameter less than the outer diameter of the bottom end, said shelf being configured and arranged to prevent portions of said liner from dropping within said crankcase.

28. The apparatus of claim12 which further comprises a seal ring located between said fire deck and said cylinder head.

29. The apparatus of claim 12 wherein said cylinder liner includes a rim section 20 proximate said cylinder head, said rim section has an outer diameter, said engine block has an inner diameter, and said outer diameter is confiolured and arranged to be a clearance fit within said inner diameter before said engine is operated and said engine i's cold and an interference fit within said inner diameter after said engine is operated and said en-ine is hot.

30. The method of claim 19 which further comprises:

providing the cylinder liner with a rim section; and sealing the top of the cooling passage with a second interference between the rim section and the engine block when the engine is hot, and having a clearance fit between the rim 3'0 section and the engine block when the engine is cold.

t8 31. The method of claim 19 which further comprises sealing below the diametral interference fit with an elastomeric o-ring.

32. The method of claim 19 wherein said providing includes an engine 5 block having a bore and a shelf at the bottom of the bore, said receiving includes the replaceable cylinder liner being within the engine block and above the shelf, and which further comprises configuring the shelf to prevent portions of the liner from dropping within the block.

10 33. An apparatus liner substantially as described hereinbefore with reference to and as shown in the accompanying drawings.

34. A method for locating and sealing a replaceable cylinder liner substantially as described hereinbefore with reference to the accompanying 15 drawings.

35. A method for retaining a replaceable cylinder liner substantially as described hereinbefore with reference to the accompanying drawings.

Amendments to the claims have been filed as follows CLAIMS 1. An apparatus comprising,:

an internal combustion engine including a cylinder head and an engine block; 5 a replaceable cylinder liner received within said encrine block; a rim section of said cylinder liner proximate said cylinder head; a midstop of said liner; wherein said cylinder liner has a first interference diametral fit within said engine block proximate to said midstop, said rim section has an outer 10 diameter, said engine block has an inner diameter, and said outer diameter is configured and arranged to be a clearance fit within said inner diameter before said engine is'operated and when said engine is cold and a second interference fit within said inner diameter after said engine is operated and when said engine is hot.

2. An apparatus according to claim 1 which further comprises a single circumferential seal aroove within said rim section.

3. An apparatus according to claim 2 which further comprises a sealing ZD 0 20 ring within said seal groove which contacts said engine block.

0 4. An apparatus according to claim 1, wherein said engine includes a crankcase, said cylinder liner has a bottom end opposite of said rim section, said engine block includes a shelf spaced apart and spaced below the bottom 25 end of said cylinder liner, said shelf being, configured and arranged to prevent IP 'D portions of said liner from droppina within said crankcase.

5. A method for retaining a replaceable cylinder liner within an engine 1 0 block of an internal combustion engine, said method comprising:

zn Z7 receiving a replaceable cylinder liner having a rim section within an engine block; flowing coolant in a cooling passage between the liner and the block; 5 sealincr the bottom of the cooling passage with a first interference fit between the cylinder liner and the engine block proximate the midstop; and sealincr the top of the cooling passage with a second interference between the rim section and the engine block.

6. A method according to claim 5 which further comprises providing the engine block with a bore and a shelf at the bottom of the bore, and configuring the shelf to prevent portions of the liner from dropping within the block.

15 7. An apparatus, comprising:

0 an internal combustion engine including a cylinder head and an engine block; a replaceable cylinder liner received within said engine block; a cooling passage surrounding a portion of said cylinder liner; and Z: C 20 a midstop below said cooling passage, a portion of said cylinder liner proximate said midstop being, in a first diametral interference fit within said engine block; wherein the first diametral interference fit seals said cooling passage proximate said midstop, said cylinder liner includes a rim section proximate 25 said cylinder head, said rim section has an outer diameter, said engine block has an inner diameter, and said outer diameter is configured and arranged to be C C, a clearance fit within said inner diameter when said engine is cold and a :D second interference fit within.said inner diameter when said engine is hot.

i.

I 8. An apparatus according to claim 7 wherein said cylinder liner includes a contact surface in contact with said cylinder head, wherein said cylinder head clamps said cylinder liner in compression between said contact surface and said midstop.

9. An apparatus according to claim 8 which further comprises a single circumferential seal groove within said rim section.

10. An apparatus according to claim 9, wherein said engine includes a 10 crankcase, said cylinder liner has a bottom end opposite of said rim section, said engine block includes a shelf spaced apart and spaced below the bottom end of said cylinder liner, said shelf being configured and arTanged to prevent portions of said liner from dropping within said crankcase.

15 11. An apparatus substantially as described hereinbefore with reference to the accompanying drawings and as shown in those drawings.

12. A method for retaining a replaceable cylinder liner within an engine C> 0 block substantially as described hereinbefore with reference to the 20 accompanying drawings.

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