Abstract:
A modular engine design system utilizes selectively replaceable components whereby a family of related engines having varying power outputs may be produced. A first series of engines utilizes a common piston operable in a cylinder of first predetermined dimensions. The engine design may utilize a first or second crankshaft/connecting rod combination to vary the power output. A modified engine design utilizes a second cylinder in addition to the first cylinder. A second series of engines utilizes a larger piston operable in a cylinder of second predetermined dimensions. The second series of engines shares a common engine design scheme with the first series of engines. However, corresponding parts are adapted for use with the larger piston/cylinder combination. The second series of engines may likewise utilize a first or second crankshaft/connecting rod combination to vary the power output. Within each series of engines, modular design concepts are utilized to provide a range of power outputs.

Description:
[0001]    This Utility Patent Application claims priority from Provisional Patent Application Serial No. 60/292,579 filed May 22, 2001. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of Invention  
           [0003]    The invention relates to the field of engines and methods of manufacturing engines and more particularly to an engine, and a method of making the engine, that allows for a number of engines of varying horsepower outputs to be manufactured from a relatively small number of basic engine components.  
           [0004]    2. Description of the Related Art  
           [0005]    Internal combustion engines are known in the art. Various methods of manufacturing such internal combustion engines have been devised and disclosed.  
           [0006]    Some have tried to streamline and improve the process of manufacturing internal combustion engines. For example, U.S. Pat. No. 4,622,864 to Fetouh purports to disclose a reciprocating piston engine including a modular power transmission sub-assembly. The invention purports to provide a lightweight and low-cost engine construction.  
           [0007]    U.S. Pat. No. 3,941,114 to Seifert purports to disclose a cylinder crankcase for a multi-cylinder internal combustion engine in which the crankcase consists of welded-together cast housing elements that are connected in series in a building-block-like matter.  
           [0008]    U.S. Pat. No. 5,456,076 to Zornes discloses an external heat source engine that includes a telescopic crankcase structure. The engine structure may be constructed so that two or more sub-systems are housed in one or more modules according to the specification of the patent. Two or more power modules may then be coupled together and engine power and speed control may be obtained by varying the relative phase angle of the couple.  
           [0009]    U.S. Pat. No. 4,676,205 to Kaufman purports to disclose and arrangement for mounting a two-stroke cycle vertical crankshaft internal combustion engine onto a rotary mower deck to accept a four-stroke cycle vertical crankshaft internal combustion engine whereby either type of engine may be adapted to the same mower deck.  
           [0010]    U.S. Pat. No. 4,610,228 to Fink et al. purports to disclose a crankcase assembly for an engine to be mounted to and associated with a portable tool such as a chain saw. A plastic crankcase is connected to the cylinder of the engine and an annular insulating member is mounted between the cylinder and the crankcase.  
           [0011]    In light of the prior art, the possibility for improvements still remain and are desirable for improving the efficiency and cost of the manufacturing process for engines, and especially smaller horsepower internal combustion engines such as might be used in the lawn care industry. In this industry, for smaller lawn care products, a large percentage of the product cost is due to the cost of the engine itself. For example, as of the date of filing this patent application, it is not uncommon for some walk behind lawn mowers to cost less than $100 even though those walk-behind lawn mowers are provided with an internal combustion engine of five horsepower or more. With cost pressure keeping the retail price of this product low, it is important that improvements in the efficiencies in the manufacture and design of the engine itself be made in order to provide adequate profit to the manufacturer of the lawn mower.  
         SUMMARY OF THE INVENTION  
         [0012]    According to one aspect of the present invention, a method of providing a family of engines so that greater manufacturing efficiencies are obtainable is disclosed. The invention provides a modular engine design system for designing a family of engines. The engines in the family of engines provide for a variety of power outputs to be achieved without major redesigning of engine components. Each engine comprises at least one cylinder block defining a cylinder therein, a crankcase having an opening therein communicating with the cylinder, a piston adapted for reciprocal movement in the cylinder, a crankshaft adapted for rotational movement within the crankcase, a connecting rod interconnecting the piston and the crankshaft, and a camshaft for controlling the intake valve and exhaust valve assembly.  
           [0013]    In accordance with the invention, the modular engine design system provides a basic engine design capable of generating a first range of power output. For illustrative purposes only, and not by way of limiting the present invention, the basic engine, for example, may be capable of generating about 3.5 to 4.5 horsepower, inclusive. The basic engine design utilizes basic engine components, designated by the letter A, which include: a first cylinder block (A) defining a first cylinder (A) of first predetermined dimensions, a first crankcase (A), a first piston (A), a first crankshaft (A), a first connecting rod (A) of length L 1 , and a first camshaft (A).  
           [0014]    In accordance with the invention, the modular engine design system provides a second engine design for providing a second engine capable of generating a second range of power output, greater than the power output of the basic engine. The modular engine design system utilizes a plurality of engine components that are substantially structurally identical to the basic engine components in order to achieve the desired power output range. For ease of illustration, different alphabetic labels will identify engine components that differ structurally from the basic engine components.  
           [0015]    The second engine design may, for example, provide an engine capable of generating about 5.0 to 6.5 horsepower. This second engine design would utilize a plurality of the basic engine components. For example, the second engine design might utilized a first cylinder block (A), defining a cylinder (A) having the same predetermined dimensions, a first piston (A), a first crankcase (A), and a first camshaft (A) are basic engine components utilized in the second engine design.  
           [0016]    However, in the inventive engine design system, several of the basic components are selectively replaceable with modified components. For instance, in the exemplary second engine design, the first connecting rod (A) is selectively replaced with a second connecting rod (B), having a length L 2 . Likewise, first crankshaft (A) is selectively replaced by second crankshaft (B). In this example, L 2  is less than L 1 . The power output is directly related to the amount of displacement, or piston stroke, of the piston within the cylinder. In a cylinder of predetermined diameter, a longer stroke correlates to a greater cylinder volume, and a shorter stroke correlates to a lesser cylinder volume. A shorter connecting rod allows for a longer stroke within cylinders of the same predetermined dimensions, and hence more power. Therefore, in the modular engine design system of the present invention, changes in the length of the connecting rod, while keeping the cylinder/piston dimensions the same, provide for the changes in power output from the basic engine to the second engine in the family of engine designs.  
           [0017]    The modular engine design system utilizes several common engine-building components that are adapted to be used with modified engine components to provide a family of engines of varying power outputs. Therefore, in the modular engine design system, greater manufacturing efficiencies can be achieved.  
           [0018]    In accordance with yet another feature of the invention, a third engine design is provided. The third engine design utilizes a third crankshaft (C) adapted to receive two first connecting rods (A, A), each having a length L 1 , which are operatively connected to two first pistons (A, A). This third engine design utilizes two of the first cylinder blocks (A, A), each of which define a first cylinder (A) of first predetermined dimensions. A modified crankcase (B) is provided which has one opening that communicates with one of the cylinders and a second opening that communicates with the second cylinder. A modified camshaft (B) is also provided to operate the valve assemblies associated with each cylinder/piston combination.  
           [0019]    In accordance with yet another feature of the invention, a fourth engine having a power output greater than the basic engine is provided through a fourth engine design. Again, a plurality of basic engine components is utilized. For example, the fourth engine design utilizes a fourth crankshaft (D) adapted to receive two of the second connecting rods (B, B), each having a length L 2 , which are operatively connected to two first pistons (A, A). The fourth engine design utilizes two of the first cylinder blocks (A, A), and the modified crankcase (B), as above. This fourth engine design utilizes the modified camshaft (B).  
           [0020]    The second engine design differs from the basic engine design mainly by differing the stroke length of the piston. The third engine design differs from the basic engine design mainly by the addition of a second cylinder/piston combination. The fourth engine design differs from the basic engine design by combining the change in stroke length of the piston with the addition of a second cylinder/piston combination. Each engine design in associated with its own crankshaft to accommodate the different stroke lengths of the pistons and/or the number of pistons.  
           [0021]    This concept of a modular engine design system that provides for a related series of engines is extended further in the present invention by providing a second series of engine designs. The second series of engine designs utilizes a common engine design scheme with the first series of engines. Therefore, the same modular concepts are used to create another family of related engines. The basic engine design of the second series utilizes a modified cylinder block (B) defining a modified cylinder (B) of predetermined dimensions greater than the dimensions of the first cylinder. The change in cylinder size provides a series of engine designs capable of providing engines with greater power output than the corresponding engines in the first series. An enlarged piston (B) is adapted for reciprocal movement within the modified cylinder (B) and is connected to another modified crankshaft (D) by a modified connecting rod (C) having length L3. A modified crankcase (C) has an opening therein adapted for communicating with the modified cylinder (B). This particular engine design utilizes yet another modified camshaft (C).  
           [0022]    The present invention is further directed to modifications in the design of the basic engine of the second series corresponding to the changes in the design of the basic engine of the first series. As in the first series, other engines in this second series are produced by utilizing a connecting rod (D) having a length L4 less than L3. Additional engines in this family are provided by utilizing a second cylinder/piston combination with shorter or longer connecting rods. As in the first series of engine designs, modifications to the crankshaft, crankcase and camshaft are also provided.  
           [0023]    In accordance with the present invention, there is provided a method of providing a family of engines sharing a common engine design scheme. The method comprises the steps of providing a first engine design for a basic engine having a first power output. The first engine is formed of basic engine components including a first cylinder block, a first crankcase, a first piston, a first crankshaft, a first connecting rod, and a first camshaft. The method further comprises the step of providing a second engine design for a second engine related to the first engine wherein at least one of the basic engine components is selectively replaced with a corresponding modified engine component substantially different from the replaced basic engine component. In that way, the second engine is associated with a power output substantially different from the first power output.  
           [0024]    According to another aspect of the invention, a common engine design scheme is adapted to utilize a second cylinder block rather than the first cylinder block. Corresponding engine parts are therefore selectively replaced for use with the second cylinder block.  
           [0025]    According to a further aspect of the invention, an engine having a first power output rating includes a crankcase that has first and second substantially symmetrical portions.  
           [0026]    According to a further aspect of the invention, the first engine includes a piston that is received for reciprocal movement within a cylinder along a piston axis, the engine including a crankcase that is divided into first and second portions along a plane that is angled relative to the piston axis.  
           [0027]    According to a further aspect of the invention, the engine includes a piston that is received for reciprocal movement with a cylinder along a piston axis, the engine including a crankcase that is divided into first and second portions along a plane that is substantially perpendicular to the piston axis.  
           [0028]    One object of the invention is to provide an internal combustion engine for the generation of power.  
           [0029]    Another object of the invention is to provide an internal combustion engine specifically adapted for smaller horsepower applications, such as lawn care products, such as lawn mowers, riding lawn mowers, snow throwers, tillers, and the like.  
           [0030]    Another object of the invention is to provide engines of varying horsepower generating capabilities that can be efficiently and inexpensively manufactured.  
           [0031]    Another object of the invention is to provide a family of engines related by use of common engine components.  
           [0032]    Another object of the invention is to provide first and second series of engines utilizing similar design modifications between family members in each series.  
           [0033]    Another object of the invention is to provide a business method whereby internal combustion engines of varying horsepower generating capabilities may be more efficiently produced.  
           [0034]    One advantage of the present invention is that engines with a wide range of power outputs can be easily provided by selective replacement of basic engine components with modified engine components.  
           [0035]    Other benefits flowing from the invention are reduced inventory costs and reduced manufacturing costs.  
           [0036]    Still other benefits and advantages of the invention will become apparent to those skilled in the art to which it pertains upon a reading and understanding of the following detailed specification. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0037]    The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail in this specification and illustrated in the accompanying drawings that form a part hereof and wherein:  
         [0038]    [0038]FIG. 1 is a perspective, partially exploded view of an embodiment of a first engine according to the invention.  
         [0039]    [0039]FIG. 2 is a perspective, partially exploded view of an embodiment of a second engine according to the invention;  
         [0040]    [0040]FIG. 3 is a perspective, partially exploded view of an embodiment of a third engine according to the invention;  
         [0041]    [0041]FIG. 4 is a perspective, partially exploded view of an embodiment of a fourth engine according to the invention;  
         [0042]    [0042]FIG. 5 is a perspective, partially exploded view of an embodiment of a fifth engine according to the invention;  
         [0043]    [0043]FIG. 6 is a perspective, partially exploded view of an embodiment of a sixth engine according to the invention;  
         [0044]    [0044]FIG. 7 is a perspective, partially exploded view of an embodiment of a seventh engine according to the invention;  
         [0045]    [0045]FIG. 8 is a perspective, partially exploded view of an embodiment of an eighth engine according to the invention; and,  
         [0046]    [0046]FIG. 9 is a flow chart for designing an engine conforming to a predetermined power output range according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0047]    With reference now to the drawings, which illustrate the preferred embodiments of the invention, FIG. 1 shows a basic engine  10  formed of a plurality of basic engine components. For ease of illustration, basic engine components will be designated with the letter (A), while modified engine components will be labeled with other alphabetic indicators. The basic engine  10  includes a cylinder block  12 (A) that has a cylindrically shaped bore therein referred to as a cylinder  14 (A). The basic engine  10  also includes a crankcase  18 (A). In the preferred embodiment, crankcase  18 (A) includes a first half  19  and a second half  20 . In the preferred embodiment the crankcase  18 (A) is split along a diagonal line  22  as illustrated.  
         [0048]    The crankcase  18 (A) includes an opening  24  adapted to communicate with cylinder  14 (A). A piston  26 (A) is adapted for reciprocal movement along a piston axis  29  through opening  24  and within cylinder  14 (A). The piston  26 (A) is operatively connected to crankshaft  35 (A) by connecting rod  30 (A). A first hole  36  in the crankcase  18 (A) receives one end  38  of the crankshaft  35 (A), while a second hole (not shown in this view) in crankcase  18 (A) receives the other end  41  of the crankshaft  35 (A).  
         [0049]    The basic engine  10  further includes a camshaft  42 (A) operably associated with the crankshaft  35 (A). Lobes  44  provided on camshaft  42 (A) direct the motion of valve assembly  48 , including tappets  50 , a first intake valve  51  and a first exhaust valve  52 . The selective opening and closing of valves in response to rotational movement of a camshaft is well known in the art. It is further known in the art to provide reciprocal movement of a piston within a cylinder through operation of a crankshaft and connecting rod.  
         [0050]    In a preferred embodiment, the specific engine size and capabilities contemplated are such that basic engine  10  could generate approximately 3.5 to 4.5 horsepower. However, it is within the scope of the present invention to design a basic engine  10  as shown in FIG. 1 having a predetermined range of power output different than the exemplary one given here.  
         [0051]    A key element of this invention is the interrelationship between the basic engine  10  shown in FIG. 1 and the other engines in the same family of engines, examples of which are illustrated in FIGS. 2 through 8. In particular, FIGS.  1 - 4  illustrate a first series of engines, while FIGS.  5 - 8  illustrate a second series of engines. In the inventive modular engine design system, one or more basic engine components that form basic engine  10  are selectively replaced with modified engine components to provide a related engine with a substantially different power output. For example the basic engine  10  of FIG. 1 uses a certain piston  26 (A), cylinder  14 (A), connecting rod  30 (A), crankshaft  35 (A), camshaft  42 (A) and crankcase  18 (A). Many of these same engine components can be used in subsequent engines having different horsepower capabilities. Further, the inventive concept can be expanded to include other engine components as well as those enumerated above. Those additional engine components include carburetors and mufflers, among others. The inventor believes that the use of identical engine components in multiple engine designs, each design having different horsepower capabilities, provides significant and substantial opportunities to lower the cost of manufacturing the engines. The basic engine structure utilizes modular first engine components that are readily adapted for selective replacement with modified engine components.  
         [0052]    For example, with reference to FIG. 2, a second engine  110  is illustrated. The engine  110  is related to basic engine  10  in that the two engine designs share many common components. In this illustrative example, second engine  110  features cylinder block  12 (A), cylinder  14 (A), crankcase  18 (A), camshaft  42 (A) and piston  26 (A). However, second engine  110  differs in design from basic engine  10  in that connecting rod  30 (A) and crankshaft  35 (A) are selectively replaced with modified components: connecting rod  30 (B) and crankshaft  35 (B).  
         [0053]    In second engine  110 , the stroke of the piston  26 (A) is longer than the stroke of piston  26 (A) in the basic engine  10 . The change in stroke is accomplished through a modified connecting rod  30 (B) having length L 2 , which is less than L 1 , and modified crankshaft  35 (B). The longer stroke length of piston  26 (A) provides a greater operative cylinder volume, even though the physical dimensions of cylinder  14 (A) remain constant between the two engine designs. The manufacturing efficiencies of the invention are attributable to the fact that in the illustrated components, only the crankshaft  35 (B) and the connecting rod  30 (B) are different, the other components in engines  10  and  110  are identical; yet they produce different horsepower capabilities. The basic engine  10  can produce, for example, approximately 3.5 to 4.5 horsepower, while the second engine  110  can produce, for example, about 5.0 to 6.5 horsepower. The engine  10  has an operative volume of about 165 cubic centimeters while engine  110  has an operative volume of approximately 210 cubic centimeters.  
         [0054]    With reference to FIG. 3, a third engine  210 , related to basic engine  10  is illustrated. The structure of third engine  210  differs from basic engine  10  in that two cylinder/piston combinations are provided. Third engine  210  is capable of significantly different power output than basic engine  10 , however, many of the basic engine components are utilized to achieve that result. For example, two of the basic cylinder blocks  12 (A) are adapted to each receive one of two pistons  26 (A). Each piston  26 (A) is operatively connected to a modified crankshaft  35 (C) through a connecting rod  30 (A). A modified camshaft  42 (B) is provided to operate the valve assemblies  48 ,  48 ′ for each cylinder/piston combination. As illustrated, a single camshaft  42 (B) is utilized to operate both valve assemblies  48 ,  48 ′. Camshaft  42 B differs from camshaft  42 A in that three lobes  44  are provided. A single lobe  44  operates both intake valves  51 ,  51 ′ while separate lobes  44  operate the exhaust valves  52 ,  52 ′. Further, a modified crankcase  18 (B) is provided having two openings  24 ,  24 ′ therein, each opening communicating with one of the cylinders  14 (A).  
         [0055]    Synergistic manufacturing advantages are available when engines conforming to the designs given above are manufactured. For example, the relationship between components used on basic engine  10 , second engine  110 , and third engine  210  has been discussed. Basic engine  10  differs from second engine  110  due to the difference in length of connecting rods  30 (A) or  30 (B). Basic engine  10  differs from third engine  210  due to the inclusion of a second piston/cylinder combination. In each of these designs, the cylinder block  12 (A) provides a cylinder  14 (A) having constant dimensions. Likewise, a common piston  26 (A) is utilized in each design.  
         [0056]    Similar efficiencies can be obtained by combining the two methods of relating engines of differing horsepower capabilities. For example, with reference to FIG. 4, a fourth engine  310  is illustrated. Providing a pair of cylinders  14 (A), a pair of pistons  26 (A), and a pair of modified connecting rods  30 (B) yields yet another related engine design. Each piston  26 (A) is operatively connected to yet another modified crankshaft  35 (D). Crankshaft  35 (D) accommodates the pair of connecting rods  30 (B). The stroke of each of the pistons  26 (A) for fourth engine  310  is comparable to the stroke of the piston  26 (A) of the second engine  110 . Therefore, fourth engine  310  provides a power output significantly different than first engine  10 , second engine  110 , and third engine  210 . Fourth engine  310  utilizes a camshaft  42 (B) to operate two sets of valve assemblies  48 ,  48 ′ in a manner similar to third engine  210 . The third engine  210  can produce, for example, approximately 7-9 horsepower, while the fourth engine  310  can produce, for example, about 10-13 horsepower.  
         [0057]    With reference now to FIG. 5, fifth engine  410  is illustrated, the design of which forms the basis for a second series of engines. A fundamental difference between basic engine  10  and the second basic, or fifth engine  410  is that the cylinders of each engine differ in physical dimensions, although a similar engine design scheme is used. Each of the previously described engines utilized cylinder  14 (A) having first predetermined dimensions. Fifth engine  410 , however, utilizes cylinder block  12 (B) that defines a cylinder  14 (B) therein. Cylinder  14 (B) has a greater diameter than cylinder  14 (A). Fifth engine  410  further utilizes a larger-sized piston  26 B adapted for the larger-sized cylinder  14 (B).  
         [0058]    A modified crankcase  18 (C) includes opening  24 (B) adapted to accommodate the larger-sized piston  26 (B). Connecting rod  30 (C) interconnects piston  26 (B) to crankshaft  35 (E). In the preferred embodiment, connecting rod  30 (C) is associated with a length L 3  which may be the same or different from L 1  or L 2 . As with the other series of engines, fifth engine 410 includes a camshaft  42 (C) operably associated with crankshaft  35 (C). An identical valve assembly  48  is operatively associated in like manner with camshaft  42 (C).  
         [0059]    FIGS.  6 - 8  are directed to a series of engines related to fifth engine  410 . The types of modifications made to basic engine  10  are repeated in this second series. For example, FIG. 6 is directed to a sixth engine  510  wherein the piston  26 (B) is connected to crankshaft  35 (F) by connecting rod  30 D having an associated length L 4 . L 4  is shorter than L 3  in order to allow a longer stroke for piston  26 (B) and thereby provide sixth engine  510  with a greater power output than fifth engine  410 . Likewise, a modified crankshaft  35 (F) is utilized to accomplish the longer stroke.  
         [0060]    [0060]FIG. 7 is directed to a seventh engine  610  having two of the larger cylinder/piston combinations. In this embodiment, each piston  26 (B) is connected to yet another modified crankshaft  35 (G) through connecting rods  30 (C) having length L 3 . A camshaft  42 (D) analogous to  42 (B) is utilized to operate the valve assemblies  48 ,  48 ′. FIG. 7 illustrates a modified crankcase  18 (B) that is split into halves  60 ,  61  along a vertical axis. This embodiment of the crankcase can be utilized in any of the previously discussed engines without departing from the scope of the invention.  
         [0061]    [0061]FIG. 8 is directed to yet another embodiment of the invention. The eighth engine  710  differs structurally from seventh engine  610  in that modified connecting rods  30 (D) are utilized. Modified crankshaft  35 H is utilized to accomplish the longer stroke of each piston  26 (B). Therefore, the power output of eighth engine is greater than fifth engine  410  and sixth engine  510  (only one cylinder/piston combination) and seventh engine  610  (shorter piston stroke).  
         [0062]    As is readily apparent to those skilled in the art, providing yet a third basic engine design would yield another series of related engines.  
                                     TABLE I                       Modular Engine Design System                                Components   Basic Engine 10   110   210   310               Cylinder Block 12   A   A   A, A   A, A       Cylinder 14   A   A   A, A   A, A       Piston 26   A   A   A   A       Connecting Rod 30   A (L 1 )   B (L 2 )   A, A   B, B       Crankcase 18   A   A   B   B       Camshaft 42   A   A   B   B       Crankshaft 35   A   B   C   D                   Basic Engine 410   510   610   710               Cylinder Block 12   B   B   B, B   B, B       Cylinder 14   B   B   B, B   B, B       Piston 26   B   B   B, B   B, B       Connecting Rod 30   C (L 3 )   D (L 4 )   C, C   D, D       Crankcase 18   C   C   D   D       Camshaft 42   C   C   D   D       Crankshaft 35   E   F   G   H                  
 
         [0063]    Table I is directed to the preferred embodiments of the family of engine designs accomplished through modifications in the first and second of basic engine designs. In the chart, the design components of the basic engine  10  are given, along with three variations ( 110 ,  210 ,  310 ). Design components of the second basic engine  410  are also given, as well as modifications thereto ( 510 ,  610 ,  710 ). It is readily seen that proving only simple alterations to the basic engine designs ( 10  and  410 ) provide engines capable of a wide range of power outputs. In the examples given above, the engines have power outputs from approximately 3.5 horsepower to up to approximately 23 horsepower.  
         [0064]    With reference to FIG. 9, a flowchart illustrating another aspect of the invention is shown. The efficiencies attributable to the invention are numerous and affect various areas of the manufacturing process. For example, because there are fewer parts due to the use of the invention, there are fewer suppliers of raw materials, components and subcomponents included in the engine. There are fewer parts to inventory. The manufacturing process will probably occupy less floor space, as multiple engine designs can most probably be built on the same production line. In FIG. 9, one such production line is illustrated in the form of a flowchart. The first block  1000  represents the step of selecting the engine design to be manufactured. For example, this document references four different engines  10 ,  110 ,  210 , and  310  that can be made with a single piston size, and anther four different engines  410 ,  510 ,  610 , and  710  that can be made with another, different single piston size. The selection of the particular engine will be greatly influenced by the amount of horsepower to be generated by the engine.  
         [0065]    With continuing reference to FIG. 9, the next block  1002  illustrates the next step of selecting which cylinder block (or blocks) corresponds to the engine design selected in step  1000 .  
         [0066]    With continuing reference to FIG. 9, the next block  1006  illustrates the next step of selecting which piston corresponds to the cylinder (or cylinders) in the engine block chosen in block  1002 . Depending on the engine design, one or two pistons can be chosen.  
         [0067]    With continuing reference to FIG. 9, the next block  1008  illustrates the next step of selecting which connecting rod (or connecting rods) corresponds to the engine design selected in step  1000 .  
         [0068]    With continuing reference to FIG. 9, the next block  1010  illustrates the next step of selecting which crankcase corresponds to the engine design selected in step  1000 .  
         [0069]    With continuing reference to FIG. 9, the next block  1014  illustrates the next step of selecting which crankshaft corresponds to the engine design selected in step  1000 .  
         [0070]    With continuing reference to FIG. 9, the next block  1018  illustrates the next step of selecting which camshaft corresponds to the engine design selected in step  1000 .  
         [0071]    It is contemplated in the present invention to utilize only one camshaft  42  on engines utilizing either one or two cylinder/piston combinations. The camshaft  42  for the two cylinder engine would be similar to the camshaft used on the single cylinder engine, except that it has an extra lobe  44 .  
         [0072]    Also, the valve assembly  48  can utilize the same lobe  44  to control the intake valves  51  for both cylinders  14  in an engine employing two cylinders. The same intake valves  51  and exhaust valves  52  are utilized for the single-cylinder and the two-cylinder engines. The intake valves  51  differ in design from the exhaust valves  52 .  
         [0073]    It is contemplated in the scope of the invention to provide both horizontally and vertically aligned engines  10 . In engines adapted for vertical alignment, modifications to the crankcase  18  could readily be made.  
         [0074]    A lubrication system is contemplated based on the modular design of the engines. The oil pump can be carried on a hollow camshaft  42  and pump oil through the interior of the camshaft. The oil would travel through the camshaft up to the upper main bearing and into the crankshaft. The crankshaft could be hollow to transfer oil to the connecting rod and the lower main bearing.  
         [0075]    The invention has been described with reference to preferred embodiment. Obviously, modifications and alterations will occur to others upon a reading and understanding of this specification. It is intended that all such modifications and alternations be included so far as they come within the scope of the appended claims or the equivalences thereof.