Patent Publication Number: US-2002007814-A1

Title: Internal combustion engine

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to internal combustion engines and, more particularly, to a compact, lightweight internal combustion engine having a plurality of pistons and cylinders, wherein the pistons are coupled to a crank on a crankshaft in a manner which maintains the pistons in straight, axial alignment within the cylinders throughout each stroke movement as the coupled attachment follows a precise cam-shaped path both under a positive downward force and during centrifugal acting outward forces while transferring lineal motion into rotating power.  
       [0003] 2. Discussion of the Related Art  
       [0004] The four cycle internal combustion engine, commonly referred to as an Otto-cycle engine, named after the inventor Nikolaus A. Otto, is widely known and used in aircraft, automotive, marine and industrial fields. Like other combustion engines, the Otto-cycle engine uses combustion chambers, wherein each combustion chamber consists of a cylinder and a closely fitted piston which slides within the cylinder. The space between the sides of the cylinder and the edges of the piston is sealed with piston rings, and friction is reduced by introducing lubricating oil along the cylinder wall. The piston is attached to a connecting rod, which in turn is coupled to a crankshaft so that the up and down reciprocating motion of the piston can be converted into rotary motion. Typically, four to eight cylinders are used, with each piston connected to the crankshaft. A gasoline and air mixture is introduced into each combustion chamber and compressed upon upward movement of the piston. The fuel air mixture is ignited at the correct moment, usually near top dead center of the piston stroke, with the use of a spark plug. In order to maintain smooth, uninterrupted rotation of the crankshaft, the cylinders must be fired in accordance with an exact timing and sequence.  
       [0005] While the Otto-cycle internal combustion engine is known to be reliable, it is limited by a low power to weight ratio which is inherent in four stroke engines. Additionally, because only a fraction of the energy of the fuel is converted to useful power, the efficiency of the Otto-cycle engine is limited. Generally, only between 18%-20% of the energy in the air/fuel mixture is converted to mechanical power, while the remainder is wasted as heat is released into the cooling system and engine exhaust. Also, a large portion of the mechanical power is further absorbed by internal friction during the remaining three cycles. Further, the complex structure of the conventional four cycle internal combustion engine makes it difficult to reduce engine size and engine weight. Moreover, the engine structure limits the use of certain materials, such as ceramics, which have become popular in engines for improving engine efficiency and power, while reducing friction. Additionally, the coupling of the connecting rods to the conventional crank requires constant pivoting and angled movement of the connecting rods as the crank rotates. This angled movement causes side loading of the piston heads against the cylinder walls, eventually causing engine wear and failure. In order to maintain a seal with the cylinder walls, piston heads in conventional four cycle internal combustion engines require high tension, high friction piston rings. The piston rod and crank arrangement in the convention four cycle combustion engine also limits each piston to one power stroke for every two complete rotations (i.e., 720°) of the crankshaft; a factor which is directly related to the engines available horsepower. To further smooth an engine&#39;s performance, cumbersome and costly counterbalance weights are needed in the design of a conventional crankshaft. Also, special consideration must be given to the proper firing order to maintain a balance.  
       [0006] The present invention overcomes many of the limitations associated with the conventional 4-cycle internal combustion engine and provides a lightweight, compact and balanced combustion engine which produces greater horsepower and fuel economy compared to a conventional 4-cycle internal combustion engine having the same number of cylinders. An important feature of the present invention is the ability to efficiently, practically and reliably convert the linear motion of reciprocating pistons into rotating power with the use of a cam crank and bearing assembly for coupling the connecting rods of the engine&#39;s pistons to the cam crank.  
       [0007] The use of cam devices to convert either linear motion into rotary motion or rotary motion into linear motion is well known. In the past, others have proposed use of various cam devices for the conversion of reciprocating motion into rotary motion in internal combustion engines. Examples of the use of cam devices in internal combustion engines are found in the U.S. patents to: Rightenour, U.S. Pat. No. 1,728,363; Napper, U.S. Pat. No. 2,528,386; and Williams, U.S. Pat. No. 5,060,603. The distinct differences between the present invention and the various cam devices used to generate power in the related art, including those disclosed in the above patents, lies in the means for attachment of the piston rods to the cam crank which enables the coupled connection to follow a specific profile or path. The present invention employs a positive mechanical means to effectively, practically, reliably and inexpensively guide, control, attach and accurately follow a cam-shaped path both under a positive downward force and during centrifugal acting outward forces within a compact unit while transferring linear motion into rotating power. The unique cam crank and piston rod coupling assembly of the present invention provides for the ease of attaching multiple linear, power-producing units to a single crank.  
       OBJECTS OF THE INVENTION  
       [0008] In view of the problems associated with conventional four stroke internal combustion engines, it is a primary object of the present invention to provide a lightweight, compact, balanced combustion engine which produces greater horsepower and fuel economy.  
       [0009] It is a further object of the present invention to provide a positive mechanical means to effectively, practically, reliably and inexpensively guide, control, attach and accurately follow a cam-shaped path both under a positive downward force and during centrifugal acting outward forces within a compact unit while transferring linear motion into rotating power.  
       [0010] It is a further object of the present invention to provide a cam device for generating rotating power with the use of a bearing assembly which couple one or more piston rods with a cam crank in a manner which allows the coupling of the piston rod to precisely follow an intricate contour of the cam crank throughout an endless path of predetermined configuration.  
       [0011] It is still a further object of the present invention to provide a means for coupling piston rods to a cam crank for converting linear motion into rotating power and maintaining the piston rods coupled to the cam crank during times when outward separating forces occur, thereby maintaining constant coupling of the piston rods to the predetermined profile of the cam without the aid of any external means or devices, such as springs.  
       [0012] It is still a further object of the present invention to provide an improved internal combustion engine which provides for twice the firing power per revolution of the crank shaft, thereby providing for more efficient use of energy created during combustion and resulting in a significant increase in power output.  
       [0013] It is yet a further object of the present invention to provide an improved internal combustion engine which includes a cam crank device and means for effectively coupling piston rods to the cam crank device, and wherein the cam crank device provides for a longer, controlled and variable lever arm, thereby providing higher torque and variable torque curves.  
       [0014] It is a further object of the present invention to provide an improved combustion engine which creates inline movement of the pistons within the cylinders, thereby eliminating side loading and reducing friction between the piston rings and cylinder walls.  
       [0015] It is a further object of the present invention to provide an improved combustion engine which requires less piston ring tension, resulting in less friction between the pistons and cylinder walls.  
       [0016] It is still a further object of the present invention to provide an improved combustion engine which requires less parts in motion, thereby reducing friction.  
       [0017] It is still a further object of the present invention to provide an improved combustion engine which produces less friction, resulting in a more economical use of fuel.  
       [0018] It is yet a further objection of the present invention to provide an improved combustion engine which incorporates a rotating crank and means of connecting multiple pistons and rods to a single crank which is inherently balanced, thereby requiring no special counterbalance measures.  
       [0019] It is yet a further object of the present invention to provide an improved combustion engine which provides a smooth, sequential firing order with less duration between power cycles, thereby generating little or no vibration without the addition of mechanical dampening devices.  
       [0020] It is still a further object of the present invention to provide an improved combustion engine which is readily adapted for use and design with ceramics, thereby providing more efficient use and containment of the heat energy of combustion, with the ability to run the engine at elevated temperatures to produce higher power levels without the use of increased amounts of fuel.  
       [0021] It is still a further object of the present invention to provide an improved combustion engine which is readily adapted for use and design with ceramics, thereby requiring little to no lubrication.  
       [0022] It is still a further object of the present invention to provide an improved combustion engine which incorporates a rotating valve assembly which is readily adapted for computer-control valve timing using common and well-developed servo motor technology, thereby providing for ultra quick and precise response timing.  
       [0023] It is still a further object of the present invention to provide an improved combustion engine having a valve assembly which is readily adapted for computer-control, thereby providing the ability to control precise timing of the engine&#39;s performance and optimizing fuel economy without sacrificing performance.  
       ADVANTAGES OF THE INVENTION  
       [0024] 1. Design  
       [0025] a) Multi-shape. The engine can be configured in any of a variety of shapes to suit the intended use (e.g., radial, in line, in pairs).  
       [0026] b) Compact.  
       [0027] c) Multi-mount (e.g., vertical shaft; horizontal shaft).  
       [0028] d) Lightweight.  
       [0029] e) Air or water cooled.  
       [0030] 2. Power  
       [0031] a) Every 360°=one power (twice as often as a conventional 4 stroke).  
       [0032] b) The ability to tailor the power curve by the shape of the crank.  
       [0033] c) The average mechanical leverage (vector force) generated per degree of rotation for the full stroke during the power cycle of the roller crank mechanism over the standard crankshaft is over 2-1.  
       [0034] By producing twice the mechanical leverage twice as often (i.e. every 360° rather than every 720°), more power is generated per equal size or the same power can be generated in a much smaller package.  
       [0035] 3. Fuel Economy  
       [0036] a) Lightweight—Less mass to move.  
       [0037] b) Friction—Axial guided rods allows for use of piston rings with less cylinder wall tension and use pistons that generate zero side loading.  
       [0038] Less ring tension results in less friction.  
       [0039] Less parts in motion results in less friction.  
       [0040] Less friction results in better use of fuel.  
       [0041] c) Rotating valve assembly—Rotary valves are easier to control using common and well-developed servo motor technology, known in the industry for ultra quick and precise response timing.  
       [0042] The advantage to computer-controlled valves is the ability to allow for precise timing of an engine&#39;s performance optimizing fuel economy without sacrificing performance.  
       [0043] d) The ease of use and design with ceramics—The most efficient total use of and containment of the heat energy of combustion and the ability to run at elevated temperatures to produce higher power levels without the use of more fuel can only be achieved with the use of ceramics.  
       [0044] Ceramics require little to no lubrication.  
       [0045] 4. Balanced  
       [0046] a) By design—The engine&#39;s rotating crank and the means of connecting multiples of piston and rods to a single crank is inherently balanced. No special counterbalance is needed.  
       [0047] b) Smooth sequential firing order (example 1-2-3) along with less duration between power cycles helps in generating little or no vibration without the addition of mechanical dampening devices.  
       [0048] 5. Efficient Conversion of Reciprocating Linear Motion into Rotating Power  
       [0049] a) Single point coupling of piston rods to cam crank in a manner as to precisely follow the intricate contour of a cam crank device whose function is both to transmit linear power of combustion into rotating force and, during the times when outward separating forces occur, to maintain constant contact to the surface and profile of the cam without the aid of any external means or devices such as a spring.  
       [0050] b) Ease of attachment of multiple piston/rod combinations to a single cam crank device.  
       [0051] 6. Piston Control and Piston Rod Weight  
       [0052] a) An engineered housing rigidly contains the entire engine assembly parts and incorporates linear guides for the piston/piston rod assembly. The linear guides restrict movement of the pistons and piston rods to linear movement, thereby allowing for the use of piston rings with less cylinder wall tension and the use of pistons that generate zero side loads. The mass, shape and the design of the piston rod combination are significantly reduced (approximately 90%). These advantages allow for the ease of sustaining higher power strokes per minute which are achieved with the use of the cam crank device.  
       [0053] 7. Multi-engine Configurations  
       [0054] a) Utilizing a single or stacked cam crank devices to create a radial, in-line or paired or cylinder arrangements, multiple engine configurations are possible.  
       [0055] b) Multi-mounting positions in either vertical shaft or horizontal shaft are also possible.  
       [0056] c) The compact size of the engine also allows for the ease of design to employ either air or water cooling.  
       SUMMARY OF THE INVENTION  
       [0057] The present invention provides a compact internal combustion engine which includes an engine housing, an arrangement of cylinders with reciprocating pistons, a crankshaft extending through the housing, a cam crank fitted to the crankshaft and rotatable with the crankshaft, and a valve assembly. Each piston includes a piston head slidably received within a respective cylinder and an integral connecting rod extending from the bottom of the piston head. A bearing arrangement couples the connecting rod of each piston to the cam crank in a manner which causes the coupling of the piston rods to follow an endless path of predetermined configuration upon reciprocating movement of the pistons and rotation of the cam crank. Upon firing of the respective cylinders, the pistons move in straight, axial alignment within the cylinders in a linear stroke movement, thereby delivering a power stroke to the cam crank, causing the coupled connecting rods to travel about the predetermined path as the cam crank is rotated. In this manner, the linear motion of the pistons is effectively, practically, efficiently and economically transferred into rotating power in a compact unit. In the preferred embodiment, the continuous path followed by the coupling of the piston connecting rod is defined by one or more cam-shaped grooves formed in the cam crank which serve to direct the reciprocating pistons through four complete strokes, including one power stroke, with each rotation of the cam crank. Accordingly, each cylinder of the engine delivers one power stroke for each rotation of the crankshaft.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0058] For a fuller understanding of the nature of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings in which:  
     [0059]FIG. 1 is an exploded perspective view of the internal combustion engine of the present invention, in accordance with a preferred embodiment thereof;  
     [0060]FIG. 2 is an isolated exploded perspective view of a portion of the crankshaft, the cam crank, a piston head and connecting rod, and a bearing assembly for coupling the piston rod to the cam crank;  
     [0061]FIG. 3 is an isolated perspective view showing a piston/piston rod coupled to the cam crank; and  
     [0062]FIG. 4 is a side elevation, in partial section, showing the piston/piston rod coupled to the cam crank. 
    
    
     [0063] Like reference numerals refer to like parts throughout the several views of the drawings.  
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0064] Referring to the several views of the drawings, the internal combustion engine of the present invention is shown and is generally indicated as  10 . The engine  10  includes an engine housing  12  defined by opposing cover members  14 ,  16  which attach together to accommodate the engine components. In one embodiment, which is shown in FIG. 1, a plurality of cylinders  20  are spaced equally around the housing  12  and are radially disposed relative to a central axis  24 . It is noted, however, that the cylinders may be arranged in a different configuration relative to the housing and central axis  24  such as, for example, a V arrangement or an in-line arrangement. The cylinders  20  are each fitted with a sleeve  22  which may be of various known materials for such use including steel, aluminum or ceramic. The inner surface  23  of the sleeve  22  defines an inner cylinder wall for engagement with rings on a piston head of pistons  60  to provide a seal between the piston head and cylinder wall as the piston head moves up and down in the cylinder.  
     [0065] The main housing  12  is structured for passage of a crankshaft  40  therethrough. While only a portion of a crankshaft  40  is shown in FIGS. 1 and 3, it is noted that the crankshaft  40  extends through the engine interior along the central axis  24 . A cam crank  50  is fitted to the crankshaft  40 , in functional alignment with the cylinders  20 , and is able to rotate with the crankshaft  40  about the central axis  24  within the housing. Bearings  52  are placed on the crankshaft  40  on opposite sides of the cam crank  50 . It is noted that while the drawings show a single cam crank  50  for purposes of clarity and to facilitate an understanding of the operational components of the invention, more than one cam crank can be fitted, in series, along the crankshaft  40 . In this instance, each cam crank  50  would be associated (i.e., aligned) with one or more cylinders  20  for driving reciprocating movement of pistons  60  therein, as described more fully hereinafter.  
     [0066] As described above, each cylinder  20  accommodates a reciprocating piston  60  having a pair of connecting rods  62 ,  62 ′ and bearings  64  for coupling the pistons  60  to the cam crank  50 . The bearings  64  are captivated between the connecting rods  62 ,  62 ′ and peripheral grooves  54 , defining a cam path on opposite sides  56 ,  58  of the cam crank  50 . The bearing coupling assembly permits movement of the cam crank  50  relative to the connecting rods  62 ,  62 ′ and pistons  60 . More specifically, as the cam crank  50  rotates, the ball bearings  64  travel along the grooves  54 , about the predetermined cam path. By changing the distance between the grooves  54  and the central axis of rotation  24  of the cam crank about the cam path, the pistons  60  are able to move up and down in a linear reciprocating motion. In a preferred embodiment, the cam crank  50  and grooves  54  are specifically configured to cause reciprocating movement of the pistons  60  through four complete strokes for each rotation of the cam crank, thereby completing a full cycle (i.e., intake, compression, combustion and exhaust) with one power stroke for each 360° rotation of the crankshaft  40 . Moreover, the configuration of the crank  50  and grooves  54  which accommodate the bearing coupling assembly can be varied in accordance with desired performance characteristics of the engine (e.g., torque curve). The coupling of the connecting rods to the cam crank, with the use of bearings  64 , further serves to maintain the connecting rods  62 ,  62 ′ in straight, axial alignment with the respective cylinder  20  throughout the stroke, thereby preventing side loading of the piston head  66  against the cylinder wall  21 .  
     [0067] Referring to FIG. 2, a detailed exploded view of a piston  60  is shown, including the connecting rods  62 ,  62 ′, the piston head  66 , and the bearings  64 . The top portions of the connecting rods  62 ,  62 ′ are provided with slotted cavities  65  which are structured and disposed for captivated receipt of a congruently configured stem structure (not shown) extending from the bottom of the piston head  66 . In assembly, the connecting rods  62 ,  62 ′ are brought together at the top portions  63  so that the slotted cavities  65  engage about and captivate the depending stem structure of the piston head  66 , thereby securing the piston head  66  to the connecting rods  62 ,  62 ′. A bolt or other means (not shown) is fitted through aligned holes  67  formed through the connecting rods  62 ,  62 ′ to hold the connecting rods together, in assembly, with the piston head  66  attached thereto. As described above, the ball bearings  64  are each captivated between a respective one of the connecting rods  62 ,  62 ′ and a respective one of the continuous grooves  54  on each side of the cam crank  50 . A socket  69  formed within the inner lower side of each connecting rod  62 ,  62 ′ accommodates a respective one of the ball bearings  64  therein so that the ball bearings  64  can freely rotate relative to the respective connecting rods  62 ,  62 ′ and the grooves  54  in the cam crank  50 . In this manner, the bearings  64  are able to travel about the cam path, defined by the direction path of the grooves  54  as the cam crank  50  rotates and the pistons  60  move in a linear reciprocating action within the cylinders.  
     [0068] The piston heads  66  are provided with a plurality of annular grooves  61  to accommodate piston rings, in the same manner as on a piston head of a conventional combustion engine. However, it is noted that due to the straight, axial movement of the pistons  60  within the respective cylinders, which avoids excessive side loading, the piston rings can be of a reduced tension, thereby exerting less friction against the cylinder walls  23 , and thereby providing more efficient use of fuel (i.e., better fuel economy).  
     [0069] The engine housing  12 , formed by the two opposing housing end covers  14 ,  16  includes guides  70  which are specifically structured and configured for sliding movement of the connecting rods  62 ,  62 ′ therein. More particularly, the guides  70 , in conjunction with the bearing  64  and groove  54  configuration, serve to hold the connecting rods  62 ,  62 ′ in the assembled condition so that they do not split apart or separate from the cam crank as a result of the force exerted downwardly on the piston  60  against the crank  50  or the centrifugal acting outward forces acting on the bearing coupling as the bearing  64  travels about the cam path. Specifically, the guides  70  surround the connecting rods  62 ,  62 ′ and prevent outward separation of the connecting rods while holding the bearings  64  captivated between the connecting rods and the respective raceways on the crank, as the piston  60  moves up and down through each stroke.  
     [0070] Each cylinder  20  is covered by a cylinder head  80  fitted to the outer side of the engine block  12 . Chambers  82  on the cylinder head  80  accommodate intake and exhaust valve members  92 ,  94 , respectively, of a rotating valve assembly  90 . A stem  98  extends from the valve members  92 ,  94  and connects to a means for operating the valve assembly  90 . In one embodiment, shown in the drawings, the valve operating means comprises an assembly of rocker arms  100 , cams  102 , lifters  104  and push rods  106 . In this embodiment, the stem  98  of each valve member  92  connects to a respective rocker arm  100 . Upon rotation of the crankshaft  40 , a cam  102  urges spring biased lifters  104  against push rods  106  to turn the respective rocker arms  100 . A slight turning of each rocker arm  100  results in outward axial movement of the respective valve member  92 ,  94  relative to the associated valve chamber  82  to open the respective valve member. In an alternative embodiment, the valve members  92 ,  94  are operated to the open and closed positions by computer control, using servo motors to move the valve members, thereby providing ultra-precise timing of the valve operation.  
     [0071] While the instant invention has been shown and described in accordance with several preferred embodiments which are believed to a best mode of the invention at the time of filing the original patent application, it is recognized that variations and departures from the instant disclosure may be made in the future and are contemplated within the spirit and scope of the invention.