Patent Publication Number: US-8978620-B2

Title: Seatless wet cylinder liner for internal combustion engine

Description:
TECHNICAL FIELD 
     The present application relates to cylinder liners for internal combustion engines, and more particularly, but not exclusively to seatless wet replaceable cylinder liners. 
     BACKGROUND 
     Present approaches to removable cylinder liners suffer from a variety of drawbacks, limitations, disadvantages and problems including those respecting machinability and amount of material used in the engine block to create features for seating of the cylinder liner and coolant passages. Therefore, there is a need for unique and inventive apparatuses, systems and methods for cylinder liners. 
     SUMMARY 
     One embodiment of the present application is a unique replaceable cylinder liner for an internal combustion engine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for seatless wet cylinder liners. Further embodiments, forms, features, aspects, benefits, and advantages shall become apparent from the description and figures provided herewith. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is an elevational cross-sectional illustration of a seatless wet cylinder liner and piston positioned in an engine block. 
         FIG. 2  is an enlarged elevational cross-sectional illustration of a portion of the  FIG. 1  cylinder liner without a piston, and further showing a portion of a cylinder head and head gasket. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific 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. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates. 
     One embodiment of the present application includes an internal combustion engine with an engine block and a cylinder liner housing a piston. The engine block includes at least one cylinder cavity and at least one replaceable cylinder liner positioned within the cylinder cavity. At least two press fit areas create an interference fit between the engine block and the replaceable cylinder liner. One press fit area is located proximate to the top surface of the engine block and the other press fit area is located in the engine block at the opposite end of the cylinder liner. A storage volume is formed between the press fit areas by the outer surface of the cylinder liner and the surface of the engine block defining the cylinder cavity. The press fit areas resist the axial load of the cylinder liner within the cylinder cavity without features such as a seat or other structure protruding from the engine block into the cylinder cavity creating an axial abutment feature for the cylinder liner. The press fit areas also seal the storage volume to prevent passage of, for example, coolant from the storage volume out of the cylinder cavity. In one embodiment, a redundant seal is provided between the cylinder liner and the engine block at the press fit area proximate the top surface or burn plate of the block. 
       FIG. 1  depicts an elevational cross sectional view of a portion of an internal combustion engine  100  including an engine block  110 , of which a portion is shown. Engine block  110  includes at least one cylinder cavity  112  receiving cylinder liner  140  defining a combustion chamber  131 . Internal combustion engine  100  may be designed with a single cylinder or multiple cylinders. Some embodiments, for example, contemplate an engine  100  with pairs of cylinders ranging from two to twenty-four cylinders, although any number of cylinders is contemplated. Engine block  110  includes a piston  130  in combustion chamber  131  slidably received within the inner diameter  122  of cylinder liner  140 . A top piston ring  136  is located within ring groove  138  of piston  130  and contacts inner diameter  122  of cylinder liner  140 , and provides a lower seal for combustion chamber  131 . A wrist pin  132  rotatably connects piston  130  to a connecting rod  134 . Connecting rod  134  is connected to a crankshaft (not shown) in a conventional manner. 
     During operation of internal combustion engine  100 , the crankshaft rotates to force piston  130  to move up and down in combustion chamber  131  under high combustion temperatures and pressures. These conditions, among others, cause cylinder liner  140  to become worn, cracked or otherwise deficient over time. Cylinder liners  140  are readily replaceable to restore appropriate clearances for the piston and other components of the cylinder, allowing for efficiency and performance improvements. In one embodiment, cylinder liner  140  is cast and cylinder cavity  112  only requires a modest amount of machining in engine block  110  to provide sliding, sealing and contact surfaces as well as a storage volume around cylinder liner  140 , although other methods of fabrication are contemplated. 
     Cylinder liner  140  may be inserted into cylinder cavity  120  under conditions that create at least two press fit areas. A press fit, also known as an interference fit or friction fit, for example, creates an axial hold where adjoining parts share the same space by creating a slight elastic deformation and a compression force between the adjoining parts. Compression from the press fit increases the friction between the adjoining parts to a point where independent movement of the adjoining parts is not possible under normal operating conditions. Press fits between the cylinder liner  140  and engine block  110  may be created using physical presses, principles of thermal expansion or other suitable method. 
     In the illustrated embodiment, assembly of cylinder liner  140  with engine block  110  in cylinder cavity  120  includes a first press fit area  150  and a second press fit area  160 . First press fit area  150  and second press fit area  160  create connections of cylinder liner  140  with engine block  110  that retain cylinder liner  140  in cylinder cavity  112  in a manner that resists axial movement of cylinder liner  140  relative to engine block  110  under operating conditions for engine  100 . Friction within the press fit areas  150 ,  160  maintains cylinder liner  140  in axial position without physical stop features such as flanges, ledges, rims, projecting edges, ridges and the like extending from engine block  110  into cylinder cavity  112 . Elimination of features in cylinder cavity  112  that create an axial abutment of cylinder liner  140  with engine block  110  reduces the amount of machining required to create cylinder cavity  112  and the amount of material required by engine block  110 . 
     Press fit areas  150 ,  160  are provided by arranging the inner diameter of cylinder cavity  112  to be slightly smaller than the outer diameter of cylinder liner  140  so that force must be applied to cylinder liner  140  to insert it into cylinder cavity  112  to overcome the interference therebetween. In the illustrated embodiment, first press fit area  150  is formed by a cylinder liner outer diameter  152  and a first cylinder cavity inner diameter  154 . Second press fit area  160  is formed by cylinder liner outer diameter  152  and a second cylinder cavity inner diameter  164 . First cylinder cavity inner diameter  154  may be the same as or differ from second cylinder cavity inner diameter  164 . Cylinder liner outer diameter  152  is slightly greater than first and second cylinder cavity inner diameters  154 ,  164  of the corresponding portions of cylinder cavity  112  into which cylinder liner  140  is press fit. Cylinder liner  140  is press fit into cylinder cavity  112  until at least a portion of upper end  144  of cylinder liner  140  is aligned with or flush with the burn plate or top surface  172  of engine block  110 . Head gasket  194  can then be positioned along top surface  172  across the junction of cylinder liner  140  with engine block  110  and secured in position with engine head  196 . 
     In the illustrated embodiment, the length of press fit area  150  along cylinder liner  140  and cylinder cavity  112  is substantially less than the length of second press fit area  160 , and the press fit of cylinder liner  140  with engine block  110  is substantially continuous along the respective lengths of press fit areas  150 ,  160 . In other embodiments, the lengths of the press fit areas  150 ,  160  are the same or approximately the same. In still other embodiments, the press fit between cylinder liner  140  and block  110  along one or both of press fit areas  150 ,  160  includes one or more discontinuities. For example, as shown in further detail in  FIG. 2 , press fit area  150  includes a discontinuity formed by recess  142  in cylinder liner outer diameter  152  and recess  190  in first cylinder cavity inner diameter  154 . A circumferential seal  192  is positioned in recesses  142 ,  190 . In one embodiment, seal  192  is an elastomeric O-ring, although other types of seals are also contemplated and not precluded. 
     A jacket region  170  is formed by cylinder cavity  112  around cylinder liner  140  via an undercut in engine block  110  between top end  172  and bottom end  174  of cylinder cavity  112 . Jacket region  170  extends along a sufficient portion of the axial length of cylinder liner  140  to provide a storage volume  180  that receives coolant, insulation or other media that provides adequately heat transfer from cylinder liner  140  during engine operation. In the illustrated embodiment, jacket region  170  includes an upper lip  176  facing an opposite bottom lip  178  and a jacket surface  182  extending between lips  176 ,  178 . Lips  176 ,  178  extend radially outwardly from cylinder liner  140  so as to not protrude into cylinder cavity  112 , and each lip  176 ,  178  defines an end of the respective press fit area  150 ,  160 . For example, press fit area  150  extends from lip  176  to top surface  172  and press fit area  160  extends from lip  178  to bottom end  146  of cylinder liner  140 . 
     The storage volume  180  allows use of a cooling or insulation media that creates a “wet” environment in which cylinder liner  140  operates. Storage volume  180  is sealed at opposite upper and lower ends by first press fit area  150  and second press fit area  160 . Additional sealing of storage volume  180  can be provided by seal  190 . In any event, coolant, insulation or other media in the storage volume  180  is sealed to prevent leakage to head gasket  194  and engine head  196 . Seal  192  provides a redundant seal that assists in maintaining the sealing of storage volume  180  as engine  100  temperatures vary between hot and cold. 
     A profile along cylinder liner  140  is created by the two press fit areas  150 ,  160  spaced from one another along the length of cylinder liner  140  by storage volume  180 . While two press fit areas are shown in  FIG. 1 , one or more additional press fit areas may be provided that form multiple storage volumes along length of cylinder liner  140 . It is also contemplated in one embodiment that the cooling media in storage volume  180  is shared with the engine cooling system, where coolant flows through storage volume  180  to maintain a suitable operating temperature for cylinder liner  140 , engine block  110  and other components. Cylinder liner  140  can be in direct contact with the coolant to provide improved heat transfer. 
     The profile along cylinder liner  140  includes a smaller axial length of press fit area  150  than the axial length of press fit area  160 , allowing cooling media in storage volume  180  to be closer to seal  192  and head gasket  194  and reduce the temperature of these components during engine operation. In addition, this smaller length for press fit area  150  aligns the upper end of storage volume  180  with the top dead center position of piston ring  136  to remove heat from piston ring  136 . The greater axial length of press fit area  160  provides sufficient frictional forces in addition to those provided by press fit area  150  to maintain an axial hold of cylinder liner  140  during engine operation. In one embodiment, the axial length of press fit area  160  is at least twice the length of press fit area  150 . 
     The arrangement of cylinder liner  140  and cylinder cavity  112  allows cylinder liner  140  to have a substantially constant outer diameter  152  from top end  144  to opposite second end  146 , with only limited interruption, such as that formed by recess  142 . Furthermore, cylinder cavity  112  can be provided with a continuous inner diameter  152 ,  154  except where the inner diameters are interrupted by jacket region  170 . However, interruptions in the interior space defined by cylinder cavity  112  that receives cylinder liner  140  is free of features such as lips, ledges, or abutments, protruding into cylinder cavity  112  that would, if present, provide an axial stop when contacted by cylinder liner  140 . 
     According to one aspect, an apparatus comprises an internal combustion engine including an engine block and at least one cylinder cavity in the engine block. The cylinder cavity includes an upper end portion and a lower end portion and an undercut region therebetween. At least one replaceable cylinder liner is received in the cylinder cavity. The cylinder liner includes a first press fit area located proximate a first end of the cylinder liner in press fit engagement with the upper end portion of the cylinder cavity and a second press fit area spaced from the first press fit area in press fit engagement with the lower end portion of the cylinder cavity. A storage volume is formed by the cylinder liner and the undercut region between the first and second press fit areas, wherein the first press fit area and the second press fit area axially secure the cylinder liner in the cylinder cavity. 
     In one refinement of this aspect, a coolant or insulation is provided in the storage volume. In another refinement of this aspect, the cylinder liner includes an annular recess in an outer surface of the cylinder liner in the first press fit area and a seal in the annular recess between the cylinder liner and the engine block. In another refinement of this aspect, the cylinder liner includes an outer diameter that is constant from the first end of the cylinder liner to an opposite second end of the cylinder liner located proximate the second press fit area, and the cylinder cavity includes a first inner diameter along the upper end portion and a second inner diameter along the lower end portion, wherein the outer diameter is greater than the first and second inner diameters. In another refinement of this aspect, the second press fit area has an axial length along the cylinder liner that is at least twice a length of the first press fit area along the cylinder liner. In yet another refinement of this aspect, the cylinder cavity is free of features that create an axial abutment of the cylinder liner in the cylinder cavity. 
     According to another aspect, an internal combustion engine includes an engine block and at least one cylinder cavity in the engine block. The cylinder cavity includes an upper end portion and a lower end portion. At least one replaceable cylinder liner is positioned in the cylinder cavity with a first press fit between the cylinder cavity and the cylinder liner proximate a first end of the cylinder liner and with a second press fit between the cylinder cavity and the cylinder liner proximate to a second end of the cylinder liner. The first press fit and the second press fit axially retain the cylinder liner against movement relative to the engine block while the cylinder cavity is free of features providing an axial abutment with the cylinder liner in the cylinder cavity. 
     In one refinement of this aspect, the cylinder liner has an outer diameter extending from the first end to the second end of the cylinder liner and the cylinder cavity has a first inner diameter at the first press fit and a second inner diameter at the second press fit, the outer diameter being greater than the first and second inner diameters. In one further refinement, the first and second inner diameters are the same. 
     In another refinement of this aspect, the cylinder cavity includes an undercut between the first press fit and the second press fit. The undercut defines a storage volume around the cylinder liner between the first and second press fits for receiving a heat transfer media. In one further refinement, the first press fit and the second press fit seal the storage volume. In another further refinement, the first press fit extends completely around the cylinder liner from a burn plate of the engine block to the undercut and the second press fit extends completely around the cylinder liner from the undercut to the second end of the cylinder liner. 
     In another refinement of this aspect, the cylinder liner includes an annular recess in an outer surface of the cylinder liner in the first press fit and a seal is positioned in the annular recess between the cylinder liner and the engine block. 
     In yet another refinement of this aspect, the second press fit has an axial length along the cylinder liner that is at least twice a length of the first press fit along the cylinder liner. 
     According to another aspect, a method comprises: forming a cylinder cavity in an engine block, wherein the cylinder cavity extends from a top surface of the engine block and includes a length having a first inner diameter portion extending from the top surface to an undercut region, and the undercut region extends along the length from the first inner diameter portion to a second inner diameter portion of the cylinder cavity, wherein the second inner diameter portion extends along the length of the cylinder cavity; placing a replaceable cylinder liner within the cylinder cavity; and establishing a fixed axial position of the cylinder liner relative to the engine block with a first press fit between an outer diameter of the cylinder liner and the first inner diameter portion of the cylinder cavity and a second press fit between the outer diameter of the cylinder liner and the second inner diameter portion of the cylinder cavity, wherein a storage volume is formed by the outer diameter of the cylinder liner and the undercut region between the first and second press fit areas. 
     In one refinement of this aspect, the cylinder liner includes a recess in the outer diameter thereof, the recess being aligned with the first inner diameter portion and the recess including a seal therein. In another refinement of this aspect, the second inner diameter portion has a length that is at least twice a length of the first inner diameter portion. In yet another refinement of this aspect, the first and second inner diameters are the same and the first interference fit and the second interference fit seal the storage volume. 
     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 in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.