Abstract:
A cam-drive engine having one or more cylinder assemblies detachably affixed to an engine core that does not include a cylinder block per se. Each cylinder assembly can be attached to or detached from the engine core without the need for disassembly of the cylinder assembly unit. This allows cylinder assemblies to be easily removed or replaced for repair or cylinder assemblies to be easily added to an existing engine. The cylinder assemblies can include cylinder pressure and solenoid actuated intake and exhaust valves that facilitate attachment. The engine can further include a catalytic converter contained in a central hub proximate to the cylinder assemblies thereby facilitating rapid warm-up of the catalyst.

Description:
FIELD OF INVENTION  
         [0001]    The present invention relates to engines and in particular to a detachable cylinder assembly for use in a cam-drive engine and to solenoid operated valves and a catalytic converter for use in this type of engine.  
         BACKGROUND  
         [0002]    Operable configurations of the reciprocating-piston internal combustion engine have been known for more than a century. In that time substantial developments have occurred that have resulted in ever higher levels of efficiency and reliability in engines being produced commercially. Despite this long legacy of improvement, these engines are still subject to wear and degraded operation with extended use. Once they have achieved long operating lives these engines commonly require internal repairs in the form of cylinder wall boring or honing and piston ring replacement.  
           [0003]    Today most reciprocating-piston internal combustion engines are built around a cylinder block housing into which are machined either the cylinder bores directly or receivers for cylinder liners. In either case, the previously mentioned internal repairs require substantial disassembly of the engine and often removal of the entire engine from its operating environment. This holds true even when the repairs are to be carried out on only one or a small number of the cylinders in a multi-cylinder engine. The removal from service and the total labor required to carry out the repairs represents a substantial cost to the engine&#39;s user in particular where the engine is being used in a commercial application.  
           [0004]    There exists a class of engines known as “cam-drive” or “swash plate” engines. These engines are often described as ‘barrel’ engines because many have a cylinder block that is substantially the shape of a large diameter, short cylinder. Although, it is well known that the “cam-drive” or “swash plate” engines have a number of benefits, the barrel configuration of the cylinder block common to this type of engine can cause difficulty in performing some maintenance or repair operations on these engines. In particular, in many implementations of the “cam-drive” or “swash plate” engine the cylinder block is a large mono-block or split-block which can require significant and complex disassembly in order to remove the pistons or to gain access to the inner cylinder walls as exemplified by the engine in U.S. Pat. No. 4,492,188 issued Jan. 8, 1985. For many of these engines it is difficult to imagine how they could receive cylinder maintenance (such as piston or ring replacement, cylinder boring or honing; etc.) without the complete removal of the engine assembly from its operating environment. Therefore, although “cam-drive” or “swash plate” engines are known to have numerous operating advantages over the more common crank-drive engines they are not superior in terms of ease of internal engine repair.  
           [0005]    Growing concerns over environmental issues has led to the widespread adoption of legislation limiting exhaust emissions from internal combustion engines. One of the most significant technologies that has been adopted to help meet these emissions restrictions is the use of catalytic converters. Although catalytic converts have proven effective at reducing emissions in normal operation they do suffer from a significant shortcoming. That is, they are relatively ineffective until a minimum operating temperature has been achieved. This has led to the introduction of numerous ancillary solutions (e.g. supplemental fast warm-up converters, heating elements in the converters, etc.) which address the period of time between engine start-up and attainment of a sufficient operating temperature in the catalytic converter. These solutions add significant cost, complexity and weight to the emissions control systems.  
         SUMMARY OF INVENTION  
         [0006]    The cam-drive engine and the cylinder assembly of the present invention are structured to permit installation and removal of the cylinder assembly to/from the engine without requiring disassembly of the cylinder assembly. The solenoid and cylinder pressure operated valves of the present invention facilitate the installation and removal of the cylinder assembly by eliminating the need for mechanical valve actuation. The catalytic converter of the present invention provides for fast warm-up of the catalyst by placing the converter proximate to the cylinder assembly.  
           [0007]    In accordance with one aspect of the present invention, a cylinder assembly for detachable mounting on a cam-drive engine core having a drive shaft, a power plate affixed to said drive shaft, a power plate housing substantially supporting said drive shaft and said power plate, a cylinder connecting rod connected to said power plate, and a cylinder assembly mounting position connected to said power plate housing, said cylinder assembly comprising: a cylinder housing with attachment apparatus for detachably mounting at said mounting position, a cylinder head assembly affixed to an end of said cylinder housing, a piston positioned inside of said cylinder housing, a piston connecting pin connected to said piston, and an aperture in said cylinder housing through which said piston connecting pin is accessible for detachable connection to said cylinder connecting rod; wherein said cylinder assembly can be attached or detached to said engine core as an assembled unit.  
           [0008]    In accordance with another aspect of the present invention, a cylinder assembly for detachable mounting on a cam-drive engine core having a drive shaft, a power plate affixed to said drive shaft, a power plate housing substantially supporting said drive shaft and said power plate, a cylinder connecting rod connected to said power plate, and a cylinder assembly mounting position connected to said power plate housing, said cylinder assembly comprising: a cylinder housing with attachment apparatus for detachably mounting at said mounting position, first and second cylinder head assemblies, one affixed to each end of said cylinder housing, first and second pistons positioned inside of said cylinder housing, a piston connecting rod connected at one end to said first piston and at another end to said second piston, a piston connecting pin connected to said piston connecting rod, and an aperture in said cylinder housing through which said piston connecting pin is accessible for detachable connection to said cylinder connecting rod, wherein said cylinder assembly can be attached or detached to said engine core as an assembled unit.  
           [0009]    In accordance with a further aspect of the present invention, a cam-drive engine core for detachable mounting of a cylinder assembly having a cylinder housing with attachment apparatus for detachable mounting, a head assembly affixed to an end of said cylinder housing, a piston positioned inside of said cylinder housing, a piston connecting pin connected to said piston, and an aperture in said cylinder housing through which said piston connecting pin is accessible, said engine core comprising: a drive shaft, a power plate affixed to said drive shaft, a power plate housing substantially supporting said drive shaft and said power plate, a cylinder connecting rod, connected to said power plate, for detachable connection to said piston connecting pin, and a cylinder assembly mounting position, for detachably receiving said cylinder assembly attachment apparatus, connected to said power plate housing; wherein said cylinder assembly can be attached or detached to said engine core as an assembled unit.  
           [0010]    In accordance with yet another aspect of the present invention, a cam-drive engine comprising: an engine core having a drive shaft, a power plate affixed to said drive shaft, a power plate housing substantially supporting said drive shaft and said power plate, a cylinder connecting rod connected to said power plate, and a cylinder assembly mounting position connected to power plate housing, and a cylinder assembly having a cylinder housing with attachment apparatus for detachable mounting at said mounting position, a head assembly affixed to an end of said cylinder housing, a piston positioned inside of said cylinder housing, a piston connecting pin connected to said piston, and an aperture in said cylinder housing through which said piston connecting pin is accessible for connection to said cylinder connecting rod; wherein said cylinder assembly can be attached or detached to said engine core as an assembled unit.  
           [0011]    In accordance with still another aspect of the present invention, a cam-drive engine comprising: an engine core having a drive shaft, a power plate affixed to said drive shaft, a power plate housing substantially supporting said drive shaft and said power plate, a plurality of cylinder connecting rods connected to said power plate, and a plurality of cylinder assembly mounting positions connected to power plate housing, and a plurality of cylinder assemblies each having a cylinder housing with attachment apparatus for detachable mounting at one of said plurality of mounting positions, a head assembly affixed to an end of said cylinder housing, a piston positioned inside of said cylinder housing, a piston connecting pin connected to said piston, and an aperture in said cylinder housing through which said piston connecting pin is accessible for connection to one of said plurality of cylinder connecting rod; wherein each of said plurality of cylinder assemblies can be individually attached or detached to said engine core as an assembled unit.  
           [0012]    In accordance with yet a further aspect of the present invention, a solenoid operated intake valve comprising: a gas flow port, a plunger, a resilient means biasing said plunger into a closed position sealing-off said gas flow port, means for locking said plunger in said closed position, and a solenoid for driving said plunger into an open position exposing said gas flow port.  
           [0013]    In accordance with still a further aspect of the present invention, a pressure differential and solenoid operated exhaust valve comprising: a gas flow port, a plunger, a resilient means damping said plunger as it is driven in to an open position, exposing said gas flow port, by a pressure differential across said plunger, a solenoid for driving said plunger into a closed position sealing-off said gas flow port, and means for locking said plunger in said closed position.  
           [0014]    In accordance with still another aspect of the present invention, a catalytic converter for proximate location to a cylinder assembly comprising: a substantially cylindrical inner body, a substantially cylindrical outer body whose radius is greater than that of said inner body, a cylinder assembly mounting position, to which said cylinder assembly can be affixed, disposed on the outer surface of said outer body, a plurality of supporting webs that extend from the inner body to the outer body, a catalytic carrier disposed within a cavity formed between said inner body, said outer body and said supporting webs, a catalyst disposed on said catalyst carrier, a first end cap sealing a first end of said cavity, an entry port in said first end cap to admit exhaust gases from said cylinder assembly to said cavity, via a exhaust runner; a second end cap sealing a second end of said cavity, an exit port connecting said cavity to the interior of said inner body, and an exhaust port in said first end cap through which exhaust gases in said inner body can flow; whereby the catalyst is effective at reducing the emissions of exhaust gases from said cylinder assembly circulated via said entry port, through said cavity to said exit port.  
           [0015]    Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0016]    The present invention will be described in conjunction with the drawings in which:  
         [0017]    [0017]FIG. 1 represents a side plan of the engine of the present invention.  
         [0018]    [0018]FIGS. 2 a - b  represent side plans of alternative embodiments of the cylinder assembly of the present invention.  
         [0019]    [0019]FIG. 3 represents a schematic perspective of a multi-cylinder embodiment of the engine of the present invention.  
         [0020]    [0020]FIG. 4 represents a plan projection of the power plate cam and cylinders of the present invention.  
         [0021]    [0021]FIGS. 5 a - b  represent side plans of the valves of the present invention in the closed and open positions.  
         [0022]    [0022]FIG. 6 represents a side plan of the cylinder assembly of the present invention with details of the oil cooling system.  
         [0023]    [0023]FIGS. 7 a - c  represent side plans of the engine of the present invention in stages of disassembly.  
         [0024]    [0024]FIG. 8 represents a perspective view of the catalytic converter of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0025]    [0025]FIGS. 1, 7 c  and the associated description represent an exemplary embodiment of an engine  20 , including a detachable cylinder assembly  50 , of the present invention. The engine  20  comprises an engine core  90  and a cylinder assembly  50 . The engine core  90  comprises a power plate assembly  40 , a hub  30  connected to the power plate assembly  40  and a cylinder connecting rod  66 . The cylinder assembly is connected to the hub  30  and to the power plate assembly  40  via the cylinder connecting rod  66 . The power plate assembly  40  comprises a drive shaft  42 , a power plate  44  affixed to the shaft and a housing  46  substantially supporting the other components. The power plate  44  may take on many forms that are well known for use in “cam-drive” or “swash plate” engines. In particular the power plate  44  can be a canted disc or a cam adapted to cooperatively transform reciprocating motion to rotational torque and therefore rotational motion of the drive shaft  42 .  
         [0026]    The hub  30  attaches to the power plate assembly  40  and provides support for the cylinder assembly  50  relative to the power plate assembly  40 . The hub  30  can, for example, be substantially cylindrical having mounting positions  33  for attaching the cylinder assemblies disposed circumferentially on its outer surface. The hub  30  can be configured to provide mounting positions for one or more cylinder assemblies. Other configurations of the engine may not include a hub  30 . The cylinder assemblies can alternatively be affixed and supported in other ways including, but not limited to, direct connection to the power plate assembly  40  or through another mounting structure which is not a hub  30  per se.  
         [0027]    It will be understood by those ordinarily skilled in the art that although the figures and descriptions of the various embodiments of the present invention focus primarily on the major structural components of the engine, the engine of the present invention would include appropriate ancillary systems (e.g. induction, exhaust, fuel delivery, ignition, lubrication, cooling and other similar systems) in order to create a running engine. These systems, except where otherwise noted, comprise well know apparatus and methods in common use.  
         [0028]    [0028]FIG. 2 a  represents the detachable cylinder assembly  50  which comprises a cylinder housing, head assemblies  54  at each of the two ends of the cylinder housing  52 , two pistons  56  mounted in the cylinder housing  52 , a piston connecting rod  58  connecting the two pistons  56  and a piston connecting pin  60  connected to the piston connecting rod  58  and extending through an aperture  62  in the cylinder housing  52 . The aperture  62  in the cylinder housing  52  is in a portion of the cylinder housing  52  that is not swept by the compression or oil-control rings  64  of the pistons  56  in normal operation. The end of the piston connection pin that extends through the aperture  62  in the cylinder housing  52  is connected to one end of a cylinder connecting rod  66 . The other end of the cylinder connecting rod  66  is connected to power transfer mechanism  68  coupled to the power plate  44 . The power transfer mechanism can, for example, take the form of opposed roller bearings with a load receiving portion of the power plate  44  (e.g. cam lobe) passing between the opposed roller bearings as the power plate  44  rotates. The power transfer mechanism can alternatively take on any of a number of forms well know for use in “cam-drive” or “swash plate” engines. The power transfer mechanism in conjunction with the power plate  44  translates the reciprocating motion of the connecting rod  66  to rotating motion of the drive shaft  42 . Reciprocating motion is imparted to the cylinder connecting rod  66  from the reciprocating motion of the pistons  56  in the cylinder housing  52 .  
         [0029]    The two pistons  56  in conjunction with the other components in the cylinder assembly  50  form two combustion chambers  70 . The two pistons  56  and the piston connecting rod  58  may be constructed in a variety of ways including: as a single unit, or as a combination of parts or assemblies. In another embodiment, the cylinder assembly  50  can comprise only a single piston  56  and a single cylinder head assembly  54  thereby forming a single combustion chamber  70 . In this configuration the piston connecting rod  58  would connect to only the one piston  56  or alternatively the piston connecting rod  58  could be deleted and the piston connecting pin  60  would connect directly to the piston  56  as represented in FIG. 2 b.    
         [0030]    The present invention provides an alternative cylinder block arrangement to the ‘barrel’ arrangement used in most “cam-drive” or “swash plate” engines. In the present invention each cylinder comprises part of a detachable cylinder assembly  50  that is not incorporated into a cylinder block per se. The cylinder assembly  50  is rather a “standalone” assembly that can be detachably affixed to the other components of the engine (i.e. the engine core  90 ) without the benefit of a cylinder block. The cylinder assembly  50  can, for example, be affixed via a hub  30 . In a further alternative embodiment, represented in FIG. 3, multiple cylinder assemblies can be affixed to the other components of the engine.  
         [0031]    With reference to FIG. 1, the hub  30  is substantially cylindrical having mounting positions  33 , for attaching one or more cylinder assemblies, disposed circumferentially on its outer surface. The mounting positions  33  can, for example, take the form of a registration slot  32  in the hub  30  and provision for mechanical fasteners  34  to secure the cylinder assembly  50 . The cylinder assembly  50  is provided with complementary mechanism such as a registration guide  72 , see also FIGS. 2 a  and  2   b , which mates with the registration slot  32  to provide alignment of the cylinder assembly relative to the power plate and provision for the complementary aspect  74  of the mechanical fasteners  34  to provide mechanical retention of the cylinder assembly. This permits engines of various configurations to be created by affixing one or more cylinder assemblies to the engine core  90 . This design would also permit an engine to be ‘upgraded’ (i.e. have its horsepower or torque generating capacity increased) through the addition of cylinder assemblies.  
         [0032]    When multiple cylinders assemblies are used, they will be attached at different locations on the outer surface of the hub  30 . FIG. 4 represents a multi-cylinder configuration where the periphery of the power plate&#39;s  44  cam lobe  80  is projected in a flat plane. An example of the relative positions of the cylinders are also presented in the flat plane projection. At any given point in the rotation of the cam  80 , the point in the combustion cycle in which each cylinder is found is a function of where the cylinder is connected to the cam  80 . In this embodiment of a cam  80  with two cycles per revolution and cylinders with a four-stroke combustion cycle, each of the four inclined faces  85   a , 85   b  on each side of the cam relates to one of the four combustion cycle strokes in sequence order (i.e. intake, compression, power and exhaust). In this example with two pistons  56  per cylinder  50 , the combustion cycle stroke represented by a given cam face  85  will be different for the upper cam face  85   a  than for its corresponding lower cam face  85   b  and therefore different for the upper piston  87  than for the lower piston  88 . This relationship is however constant. Understanding this relationship, the relative placement of multiple cylinders can be determined to meet appropriate operating considerations (e.g. balanced power delivery). To facilitate configuration of multi-cylinder engines the cylinder assembly mounting positions  33  can be located on the hub  30  at fixed intervals (e.g. spaced 5 degrees of arc apart).  
         [0033]    It will be understood that the structure of the modular engine described herein can facilitate eventual repairs that may be necessary to the pistons  56 , pistons rings  64 , inner surfaces of the cylinders or other similar components of the engine. The mechanisms that allow a cylinder assembly  50  to be readily affixed to the engine core  90  as an assembled unit also allow it to be readily detached as an assembled unit. This permits repairs by either: removing the cylinder assembly  50 , repairing its components and replacing the cylinder assembly  50 ; or by removing the cylinder assembly  50  and completely substituting it with a replacement cylinder assembly  50 . This approach applies individually to each cylinder assembly  50  in an engine with multiple cylinder assemblies. Thereby only those cylinder assemblies that require repair are directly affected in the repair operation. It will be possible in some installations to remove and replace one or more cylinder assemblies without having to remove the entire engine from its operating environment. A further possibility exists that in some engine configurations it may be possible to resume operation of the engine with one or more cylinder assemblies removed during the time the repairs are carried out.  
         [0034]    In addition, a manufacturer of the engine could design a set of components such that a single hub  30  configuration and a single power-plate housing  46  configuration and its associated components (i.e. a single engine core  90  configuration) could be used in engines with a variety of different cylinder assembly configurations (not illustrated). The cylinder assembly  50  configurations could vary in terms of cylinder displacement, operating cycle (e.g. two- or four-stroke), ignition/combustion type (e.g. Otto or Diesel) and other similar variations. Engines of various characteristics could be created by connecting cylinder assemblies  50 , selected from the different configurations, to engine cores  90  of a common configuration.  
         [0035]    In order to facilitate installation and removal of the cylinder assembly intake and exhaust valves that do not require direct mechanical actuation via camshaft or push-rod can be used. Valves that operate on cylinder pressure or via solenoid actuation would be suitable. Each valve  100  uses a plunger  110  to seal-off (close), as represented in FIG. 5 a , or expose (open), as represented in FIG. 5 b , a gas flow port  120 . The valves  100  can, for example, be mounted in the cylinder head assembly  54  as represented in FIG. 5 a.    
         [0036]    The intake valve  100  uses an electrical solenoid  170  to draw the plunger  110  into the open position. A return spring  180  is used to drive the plunger  110  into the closed position. Closing of the valve  100  can be assisted by the pressure differential between the combustion chamber  70  and pressure acting on the backside of the plunger  112  or by a second solenoid (not shown) driven opposite to the opening solenoid  170 . The pressure on the backside of the plunger  112  can be tailored using a number of mechanisms including use of a return spring  180  biased to closing the plunger  110 , sealing or venting of the cavity behind the plunger  110 , application of lubricating oil pressure or other similarly well know methods. When the valve  100  is in the closed position, a check ball  130  is used to lock it into position thereby preventing elevated combustion chamber  70  pressures from pushing the valve  100  open. The check ball  130  is driven into a locking race  135  in the plunger  110  by a locking solenoid  140 . The locking solenoid  140  acts on the check ball  130  via a locking block  145 . The locking block  145  is of a ramped design so that forces acting to push the check ball  130  out of the locked position will cause the check ball  130  to ride up the ramp and bind the check ball  130  in its ball run  138 . A biasing pressure provided by the flow of lubricating oil through the valve assembly pushes the check ball  130  out of the locked position when the locking solenoid  140  releases the check ball  130 . The lubricating oil supply  150  pressurizes the plunger side of the check ball  130  while oil return  155  occurs on the locking block  145  side of the check ball  130  thereby creating a pressure differential across the check ball  130 . The plunger  110  is equipped with oil control seals  160  to prevent oil leakage into the combustion chamber  70 . The plunger  110  is also equipped with pressure control seals  165  to prevent pressure leaks from or to the combustion chamber  70  when the valve  100  is closed.  
         [0037]    The exhaust valve has a similar structure but different operation from the intake valve. Exhaust valve  100  is driven open by the pressure differential between the combustion chamber  70  and pressure acting on the backside of the plunger  112 . The pressure on the backside of the plunger  112  can be tailored using methods as described for the intake valve  100 . The pressure on the backside of the plunger  112  can be used to damp or control the speed at which the exhaust valve plunger  110  is driven open. An electrical solenoid  170  is used to drive the plunger  110  into the closed position. The plunger  110  is locked into the closed position using a check ball  130  as described for the intake valve. The plunger  110  is also equipped with oil control seals  160  and pressure control seals  165  similar to the intake valve  100 . It will be understood that other well know mechanisms (e.g. pneumatic actuators) can be substituted for the electrical solenoids described in the intake and exhaust valves  100 .  
         [0038]    Use of valves  100  that operate on cylinder pressure or via solenoid  170  actuation can facilitate modular operation of the engine. Modular operation refers to the technique of temporarily “turning-off” or disabling one or more cylinders in a multi-cylinder engine under certain operating conditions such as partial load situations. The engine of the present invention can be configured for modular operation using well known methods for controlling ignition, fuel delivery and intake and exhaust valve operation on a selective basis. The valves  100  of the present invention lend themselves well to use in modular operation compared to traditional camshaft or push-rod actuated valves.  
         [0039]    In a further embodiment of the present invention, represented in FIG. 6, that can facilitate the installation and removal of the cylinder assembly  50 , lubricating oil is used to cool the pistons  56  and cylinder assembly  50 . Each piston  56  is provided with a substantially annular cooling cavity  200  between top and bottom oil control rings  64 . Pressurized lubricating oil enters the cooling cavity  200  through an entry passage  210  in the cylinder housing  52 , circulates around the piston  56  and exits via an exit passage  220  in the cylinder housing  52 . Cooling is achieved by heat conduction to the oil from the piston  56  body and the walls of the cylinder housing  52 . The cooling capacity can be increased by increasing the surface area of the piston  56  exposed to the oil. This can be achieved, for example, by the provision of cooling fins  230  on the piston  56  in the cooling cavity  200 . The oil also lubricates through contact with the walls of the cylinder housing  52  and the piston rings  64 . Oil control rings  64  on the pistons  56  prevent or minimize oil leaks into the combustion chamber  70  or into the portion of the cylinder housing  52  containing the aperture  62  for the piston connecting pin  60 . The use of lubricating oil for piston  56  and cylinder assembly  50  cooling eliminates the need for a separate cooling system (e.g. a water jacket based system using a water/glycol coolant) and the associated components and connections. This simplifies the installation and removal of the cylinder assemblies  50  by reducing the number of couplings required.  
         [0040]    Engine oil is supplied from an oil pump  240  located, for example, in the power plate assembly  40 . Oil from the pump  240  is routed to the cylinder assembly  50  via an oil supply runner  250 —e.g. a pressure resistant tube. The oil supply runner  250  is connected to an oil entry passage  210  in the cylinder assembly  50  via a detachable coupling  255 . Similarly the return oil from the cylinder assembly  50  is routed via an oil return runner  260  to the oil sump  270  which can be located, for example, in the power plate assembly  40 . The oil return runner  260  is connected to an oil exit passage  220  in the cylinder assembly  50  via a detachable coupling  255 .  
         [0041]    Removal of the cylinder assembly  50  begins with the de-coupling of the ancillary systems as represented in FIG. 7 a . This includes disconnecting the oil supply  250  and oil return  260  runners from the cylinder assembly  50  via their detachable couplings  255 . Electrical voltage supply and grounding  300  for systems such as spark ignition or glow plugs, fuel injectors and solenoid operated valves, which may be provisioned on the cylinder assembly  50  depending on the specific configuration, are disconnected via detachable electrical connectors  305 . Disconnection of the exhaust system can be facilitated by equipping the exhaust runner  310  connecting the exhaust port of the cylinder head assembly  54  with the downstream exhaust system (manifold, catalytic converter, header pipe, etc.) with an easily detachable gas tight coupling  320  such as a flare fitting. A similar approach can be used to attached the intake runner  330 , which is feed from the upstream intake system, to the intake port in the cylinder head assembly  54 .  
         [0042]    Once the various ancillary systems have been disconnected, as represented in FIG. 7 b , the next step in the removal of the cylinder assembly  50  is disconnection of the mechanical components. The cylinder connecting rod  66  can be released from the piston connecting pin  60  via a rod end, spherical or similar joint that connects the two. The other end of the cylinder connecting rod  66  can be left attached. Alternatively, if desired, the connecting rod  66  can be disconnected from the power plate  44  by freeing the guide bearings  350 , that support the cylinder connecting rod  66 , attached to the power plate housing  46  and then releasing the power transfer mechanism  68  at the end of the cylinder connecting rod  66  from the power plate  44 . Removal of the cylinder assembly  50  proper is accomplished by removing the mechanical fasteners  34  that hold the cylinder assembly  50  at the mounting positions  33  on the outer surface of the hub  30  and extracting the cylinder assembly  50 . The separated components are represented in FIG. 7 c . Thus removal and in the reverse process—installation—of the cylinder assembly  50  is accomplished with the cylinder assembly  50  as an assembled unit. It is not necessary to disassembly the cylinder assembly  50  in order to install it in or remove it from the engine.  
         [0043]    In another embodiment of the present invention, the hub  30  can house a catalytic converter for use in reducing exhaust gas emissions. FIG. 8 represents a hub  30  which comprises a substantially cylindrical inner body  410 , a substantially cylindrical outer body  420  and a series of supporting webs  430  extending radially from the inner body to the outer body. The webs enclose cavities  440  between the inner  410  and outer  420  bodies. One or more of these cavities  440  can contain a catalytic carrier  460  and a catalyst  465 . Exhaust from the cylinder assembly  50 , via an exhaust runner  310 , enters the cavity  440  through a port  455  in an end cap  450  otherwise sealing the cavities  440  at one end of the hub  30 . The other end of the hub  30  is sealed with another cap  460  without a port to the cavity. Exhaust gases having entered via the port  455  and having been exposed to the catalyst  465  exit via a port or ports  415  in the inner body  410 . Exhaust gases leave the inner body  410  via an exhaust port  400  in end cap  450  to the downstream exhaust system (not illustrated). It will be understood that the exhaust gas flow could alternatively follow the reverse path—entering the inner body  410  via port  460 , then flowing to the cavity  440  via a port or ports  415  in the inner body  410  and exiting via the port  455  in the end cap  450  to the downstream exhaust system. In alternate embodiments there could be multiple ports  455  in the end cap, there could be ports  455 , 400  in both of the end caps  450 , 460  or the ports  455  could alternatively be in the outer body  420 . Depending on the size of the cavity  440 , one or more cylinders could exhaust into the same cavity  440  or one cylinder could exhaust into more than one cavity  440 . In this embodiment the close proximity of the catalytic converter in the hub  30  to the cylinder assembly  50  may allow the elimination of certain ancillary emissions control systems which are directed to dealing with the catalyst warm-up issue. The catalyst  465  in the hub  30  will achieve operating temperature more quickly than will the catalyst in a converter mounted substantially downstream in the exhaust system as is typically the case.  
         [0044]    It will be apparent to one skilled in the art that numerous modifications and departures form the specific embodiments described herein may be made without departing from the spirit and scope of the invention.