Abstract:
A power-generation device comprising at least one cylinder, at least one cylinder head, at least one piston having a crown for improved lubricant circulation and an output shaft, having a central axis having a fixed angular relationship to the central axis of the cylinder. A swash plate, having a first swash plate surface having a normal axis disposed at a first fixed angle to the central axis of the output shaft, is fixed to the output shaft. At least one connecting rod is connected to at least one piston. At least one follower is secured to the second end of a connecting rod. The first follower surface contacts, and conforms to, the orientation of the first swash plate surface.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part patent application of copending U.S. Ser. No. 11/584,928, filed Oct. 23, 2006, which is a continuation of U.S. Ser. No. 10/939,010, now U.S. Pat. No. 7,137,366, filed Sep. 10, 2004. 
     
    
     TECHNICAL FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to engines, and in particular to swash plate internal combustion engines. 
       BACKGROUND OF THE INVENTION 
       [0003]    An internal combustion engine derives power from the volumetric compression of a fuel-air mixture, followed by a timed ignition of the compressed fuel-air mixture. The volumetric change generally results from the motion of axially-reciprocating pistons disposed in corresponding cylinders. In the course of each stroke, a piston will vary the gas volume captured in a cylinder from a minimum volume to a maximum volume. In an Otto cycle, or “four-stroke” internal combustion engine, the reciprocal motion of each piston compresses the fuel-air mixture, receives and transmits the force generated by the expanding gases, generates a positive pressure to move the spent gases out the exhaust port and generates a negative pressure on the intake port to draw in a subsequent fuel-air gas charge. 
         [0004]    The modern internal combustion engine arose from humble beginnings. As early as the late 17 th  century, a Dutch physicist by the name of Christian Huygens designed an internal combustion engine fueled with gunpowder. It is believed that Huygens&#39; engine was never successfully built. Later, in the early nineteenth century, Francois Isaac de Rivaz of Switzerland invented a hydrogen-powered internal combustion engine. It is reported that this engine was built, but was not commercially successful. 
         [0005]    Although there was a certain degree of early work on the idea of the internal combustion engine, development truly began in earnest in the mid-nineteenth century. Jean Joseph Etienne Lenoir developed and patented a number of electric spark-ignition internal combustion engines, running on various fuels. The Lenoir engine did not meet performance or reliability expectations and fell from popularity. It is reported that the Lenoir engine suffered from a troublesome electrical ignition system and a reputation for a high consumption of fuel. Approximately 100 cubic feet of coal gas were consumed per horsepower hour. Despite these early setbacks, a number of other inventors, including Alphonse Beau de Rochas, Siegfried Marcus and George Brayton, continued to make substantial contributions to the development of the internal combustion engine. 
         [0006]    An inventor by the name of Nikolaus August Otto improved on Lenoir&#39;s and de Rochas&#39; designs to develop a more efficient engine. Well aware of the substantial shortcomings of the Lenoir engine, Otto felt that the Lenoir engine could be improved. To this end, Otto worked to improve upon the Lenoir engine in various ways. In 1861, Otto patented a two-stroke engine that ran on gasoline. Otto&#39;s two-stroke engine won a gold medal at the 1867 World&#39;s Fair in Paris. Although Otto&#39;s two-stroke engine was novel, its performance was not competitive with the steam engines of the time. A successful two-stroke engine would not be developed until 1876. 
         [0007]    In or around 1876, at approximately the same time that an inventor named Dougald was building a successful two-stroke engine, Klaus Otto built what is believed to be the first four-stroke piston cycle internal combustion engine. Otto&#39;s four-stroke engine was the first practical power-generating alternative to the steam engines of the time. Otto&#39;s revolutionary four-stroke engine can be considered the grandfather of the millions of mass-produced internal combustion engines that have since been built. Otto&#39;s contribution to the development of the internal combustion engine is such that the process of combusting the fuel and air mixture in a modern automobile is known as the “Otto cycle” in his honor. Otto received U.S. Pat. No. 365,701 for his engine. 
         [0008]    Ten years after Klaus Otto built his first four-stroke engine, Gottlieb Daimler invented what is often recognized as the prototype of the modern gasoline engine. Daimler&#39;s engine employed a single vertical cylinder, with gasoline imparted to the incoming air by means of a carburetor. In 1889, Daimler completed an improved four-stroke engine with mushroom-shaped valves and two cylinders. Wilhelm Maybach built the first four-cylinder, four-stroke engine in 1890. The carbureted four-stroke multi-cylinder internal combustion engine became the mainstay of ground transportation from the early 1900s through the 1970s, ultimately being supplanted by fuel-injected engines in the 1980s. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention is a swash-plate engine having a number of features and improvements distinguishing it not only from traditional crankshaft engines, but also from prior swash plate designs. 
         [0010]    In a first embodiment, the present invention is a power-generation device comprising at least one cylinder having an internal volume, an internal cylinder surface, a central axis, a first end and a second end. At least one cylinder head, having an internal cylinder head surface, is disposed at, and secured to, the first end of one of the at least one cylinders. At least one piston, having an axis of motion parallel to the central axis of at least one of the cylinders, and having a crown disposed toward the internal surface of the cylinder head secured to that cylinder, is disposed in the internal volume of the cylinder. The crown of the piston, an internal cylinder surface, and the internal surface of the cylinder head for that cylinder together form a combustion chamber for that cylinder. 
         [0011]    The first embodiment further includes an output shaft, having a central axis having a fixed angular relationship to the central axis of the cylinder. A swash plate, having a first swash plate surface having a normal axis disposed at a first fixed angle to the central axis of the output shaft, is fixed to the output shaft. At least one connecting rod, having a principal axis, a first end axially and rotationally fixed to a piston, and a second end, is secured to at least one piston. At least one follower, having a first follower surface having a normal axis disposed at the first fixed angle to the principal axis of the connecting rod to which it is secured, is secured to the second end of a connecting rod. The first follower surface contacts, and conforms to, the orientation of the first swash plate surface. 
         [0012]    In a second embodiment, the present invention is a power-generation device comprising an output shaft, having a central axis, and at least two cylinders, disposed symmetrically about the central axis of the output shaft. Each cylinder has a central axis parallel to the central axis of the output shaft, an internal volume, an internal cylinder surface, a central axis, a first end and a second end. 
         [0013]    At least two cylinder heads, each having an internal cylinder head surface, is disposed at, and secured to, the first end of one of the cylinders. The device includes at least two pistons, each piston having an axis of motion aligned to the central axis of a cylinder, disposed in the internal volume of the cylinder and having a crown disposed toward the internal surface of the cylinder head secured to that cylinder. The crown of the piston, an internal cylinder surface, and the internal surface of the cylinder head for that cylinder together form a combustion chamber for that cylinder. 
         [0014]    A swash plate is fixed to the output shaft, having a swash plate clocking interface fixed to the orientation of the output shaft about the central axis of the output shaft. At least two connecting rods, each having a principal axis, a first end and a second end are each axially and rotationally fixed to a piston. At least two followers, having a follower clocking interface fixed to the orientation of the connecting rod about the principal axis of the connecting rod and the orientation of the swash plate clocking interface, are each secured to the second end of a connecting rod. 
         [0015]    In a third embodiment, the present invention is a power-generation device comprising an output shaft, having a central axis, four cylinders, disposed symmetrically and regularly about the central axis of the output shaft and axially-movable with respect to the output shaft, four cylinder heads, and four pistons connected to a swash plate by four followers. 
         [0016]    The four cylinders are disposed symmetrically and regularly about the central axis of the output shaft and are axially-movable with respect to the output shaft. Each cylinder has a central axis parallel to the central axis of the output shaft, an internal volume, an internal cylinder surface, a central axis, a first end and a second end. The four cylinder heads, each have an internal cylinder head surface, an intake port, and an exhaust port. Each such cylinder head is disposed at, and secured to, the first end of a cylinder. 
         [0017]    Each of the four pistons has an axis of motion aligned to the central axis of a cylinder, is disposed in the internal volume of the cylinder, and has a crown disposed toward the internal surface of the cylinder head secured to that cylinder. The crown of the piston, an internal cylinder surface, and the internal surface of the cylinder head for that cylinder together form a combustion chamber for that cylinder. 
         [0018]    The swash plate is fixed to the output shaft, and has a substantially-planar swash plate surface having a normal axis disposed at an angle of approximately 45 degrees to the central axis of the output shaft. The four connecting rods, each having a principal axis, a first end axially and rotationally fixed to a piston, and a second end, are connected to the swash plate by four followers, each secured to the second end of a connecting rod. Each of the followers has a substantially-planar follower surface fixed to the connecting rod and has a normal axis disposed at an angle of approximately 45 degrees to the central axis of the output shaft. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    For more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying Figures. 
           [0020]      FIG. 1  depicts a partial cutaway isometric view of an internal combustion engine according to one embodiment of the present invention; 
           [0021]      FIG. 2  depicts an isometric view of the reciprocating assembly of the internal combustion engine of  FIG. 1 ; 
           [0022]      FIG. 3  depicts an front view of the reciprocating assembly of the internal combustion engine of  FIG. 1 ; 
           [0023]      FIG. 4  depicts an right side view of the reciprocating assembly of the internal combustion engine of  FIG. 1 ; 
           [0024]      FIG. 5  depicts a top view of the reciprocating assembly of the internal combustion engine of  FIG. 1 ; 
           [0025]      FIG. 6  depicts an isometric view of a piston used in the reciprocating assembly of  FIG. 2 ; 
           [0026]      FIG. 7  depicts a front view of a piston used in the reciprocating assembly of  FIG. 2 ; 
           [0027]      FIG. 8  depicts a side view of a piston used in the reciprocating assembly of  FIG. 2 ; 
           [0028]      FIG. 9  depicts a top view of a piston used in the reciprocating assembly of  FIG. 2 ; 
           [0029]      FIG. 10  depicts an isometric view of the swash plate used in the reciprocating assembly of  FIG. 2 ; 
           [0030]      FIG. 11  depicts a front view of the swash plate used in the reciprocating assembly of  FIG. 2 ; 
           [0031]      FIG. 12  depicts a side view of the swash plate used in the reciprocating assembly of  FIG. 2 ; 
           [0032]      FIG. 13  depicts a top view of the swash plate used in the reciprocating assembly of  FIG. 2 ; 
           [0033]      FIG. 14  depicts a side section view of the cylinder head and crankcase assembly of  FIG. 1 ; 
           [0034]      FIG. 15  depicts an isometric section view of the cylinder head along line  15 - 15  of  FIG. 14 ; 
           [0035]      FIG. 16  depicts an isometric section view of the cylinder head along line  16 - 16  of  FIG. 14 ; 
           [0036]      FIG. 17  depicts an isometric section view of the piston according to one embodiment of the present invention; 
           [0037]      FIG. 18  depicts a side section view of the piston shown in  FIG. 17  in one position within the cylinder; 
           [0038]      FIG. 19  depicts a side section view of the piston shown in  FIG. 17  in another position within the cylinder showing an exhaust port; 
           [0039]      FIG. 20  depicts a cross section view of the piston along line  20 - 20  of  FIG. 17 ; and 
           [0040]      FIG. 21  depicts a cross section view of the piston along line  21 - 21  of  FIG. 17 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0041]    Although the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the invention. 
         [0042]    Engine  100  incorporates cylinder block  102  and crankcase  104  disposed about output shaft  106 . A swash plate  108  is rigidly secured to the output shaft  106 . Swash plate  108  has a generally-planar bearing surface  118  having a normal axis disposed at an angle to the principal longitudinal axis of the output shaft  106 . A set of four cylindrical pistons  110  are disposed in four corresponding cylinders  112  and operably connected to swash plate  108  through connecting rods  114  via rod feet  116 , which ride on bearing surface  118  of swash plate  108 . Each of rod feet  116  has a generally planar bottom surface having a principal normal axis disposed at an angle to the principal longitudinal axis of the connecting rod  114  to which it is secured. 
         [0043]    Each piston  110  incorporates a skirt  150  and a crown  152 . In the embodiment shown in  FIGS. 1-9 , the crown  152  incorporates a pair of valve pockets  154  and  156 , although alternate embodiments may omit either or both of pockets  154  and  156 . Similarly, while pockets  154  and  156  are shown as being symmetrical and having a particular shape, pockets  154  and  156  may have different shapes in alternate embodiments. 
         [0044]    Piston skirt  150  incorporates a compression ring groove  158  and oil control rings  160  and  162 . Alternate embodiments may incorporate more or fewer piston ring grooves  158 - 162  as a particular application demands. It will be understood by those of skill in the art that a wide variety of piston ring styles may be employed in the present invention, again depending on the particular application. 
         [0045]    Connecting rod  114  connects piston  150  to an elliptical rod foot  116 . Rod foot  116  incorporates an upper surface  164 , a lower surface  166  and an outer edge  168 . When assembled to swash plate  108 , rod foot  116  is captured by inner ridge  120  and outer ridge  122  against upper surface  164 , while lower surface  166  rides against swash plate bearing surface  118 . Swash plate  108  incorporates a conical transition  200  to brace the wash plate  108  against moment loading on the swash plate bearing surface  118 . 
         [0046]    Those of skill in the art will recognize that engine  100  differs markedly from traditional internal combustion engines. In the most common layout of the traditional internal combustion engine, the engine&#39;s pistons are tied to a rotary crankshaft through a set of connecting rods, in order to convert the reciprocal axial motion of the pistons into continuous rotary motion of the crankshaft. Although a wide variety of cylinder layouts have been devised and implemented, including the well-known “V” geometry (as in “V8”), in-line, opposed (also known as “flat”) and radial geometries, all such engines share the basic crankshaft geometry described above. 
         [0047]    Despite their overwhelming successes, crank-articulated reciprocating powerplants incorporate certain inherent limitations. Except at two discrete points in the range of piston motion—namely top dead center and bottom dead center—the connecting rod is disposed at an angle to the center line of the cylinder within which the piston is exposed. Axial forces in the connecting rod must, therefore, be counteracted at the interface between the piston and the cylinder wall. The load on the cylinder wall by the piston is known as “side loading” of the piston. As the pressure in the cylinder rises, side-loading can become a serious concern, with respect to durability as well as frictional losses. Further, dynamic centrifugal loads on the engine components rise geometrically with engine speed in a crankshaft engine, limiting both the specific power output and power-to-weight ratio of crankshaft engines. 
         [0048]    In a crankshaft engine, the geometry of the crankshaft and connecting rod is such that, as the crank rotates and the piston moves through its range of motion, the piston spends more time near bottom dead center (where no power is generated) than near top dead center (where power is generated). This inherent characteristic can be countered somewhat with the use of a longer connecting rod, but the motion of the piston with respect to time can only approach, and cannot ever match, perfectly sinusoidal motion. The magnitude of this effect is inversely related to the ratio of the effective length of the connecting rod to the length of the crankshaft stroke, but is particularly pronounced in engines having a connecting rod-to-stroke ratio at or below 1.5:1. 
         [0049]    The rate of acceleration of the piston away from top dead center in an engine having a low rod-to-stroke ratio is such that useful combustion chamber pressure cannot be maintained at higher crank speeds. This occurs because the combustion rate of the fuel-air mixture in the combustion chamber, which governs the pressure in the combustion chamber, is limited by the rate of reaction of the hydrocarbon fuel and oxygen. In a long stroke, short rod engine running at a high crankshaft speed, the increase in volume caused by the piston motion outstrips the increase in pressure caused by combustion. In other words, the piston “outruns” the expanding fuel-air mixture in the combustion chamber, such that the pressure from the expanding mixture does not contribute to acceleration of the piston or, therefore, the crankshaft. 
         [0050]    The dwell time of the piston near top-dead-center can be increased somewhat through the use of a larger rod-to-stroke ratio. A larger rod-to-stroke ratio can be achieved either with a shorter stroke or a longer connecting rod. Each of the two solutions presents its own problems. With respect to the use of a shorter stroke, although shorter stroke engine can be smaller and lighter than a longer stroke engine, the advantages are not linear. For example, the length of the crankshaft stroke does not have any effect on the size and weight of the pistons, the cylinder heads, the connecting rods or the engine accessories. A shorter stroke does allow for a somewhat smaller and lighter crankshaft and cylinder block, but even these effects are not linear, that is, a halving of the crankshaft stroke does not allow for a halving of the mass of the crankshaft or cylinder block. 
         [0051]    With all other performance-related engine attributes being equal, a shorter-stroke engine will have a proportionally-lower displacement as compared to a longer-stroke engine. Accordingly, the shorter-stroke engine will generally produce a lower torque output as compared to the longer-stroke engine. This lower torque output translates to a lower power output at the same crankshaft speed. Accordingly, the shorter-stroke engine will have to be run at a higher speed in order to generate the same power output. The loss of torque resulting from the lower displacement could also be offset with efficiency enhancements, such as more-efficient valve timing, better combustion chamber design or a higher compression ratio. More efficient valve timing and combustion chamber designs, however, generally require substantial investment in research and development, and the maximum compression ratio in an internal combustion engine is limited by the autoignition characteristics of the engine fuel. For naturally-aspirated engines running premium grade gasoline, there is a practical compression ratio limit of approximately 11:1 imposed by the autoignition characteristics of the fuel-air mixture, thereby limiting the efficiency improvements available from an increase in compression ratio alone. 
         [0052]    The lost output caused by the shortening of the stroke can also be recouped by increasing the bore diameter of the engine cylinders, thereby increasing engine displacement. While the displacement of the engine is linearly proportional to the stroke length, it is geometrically proportional to the cylinder bore diameter. Accordingly, a 10% reduction in stroke length can be more than offset with a 5% increase in cylinder bore diameter. All other things being equal, an increase in cylinder bore diameter requires an increase in piston mass, which requires a corresponding increase in connecting rod strength and crankshaft counterweight mass. If two or more of the engine&#39;s cylinders are arranged in a line, as is common in most modern crankshaft engines, the larger-diameter cylinders will also require a longer cylinder block, cylinder heads and crankshaft, thereby increasing engine size and weight. 
         [0053]    A second approach to increasing the rod-to-stroke ratio is to lengthen the rods. This has the advantage of increasing the rod-to-stroke ratio without reducing the engine displacement. Lengthening the rods while leaving all other parameters of the engine alone, however, will move the top-dead-center position of the pistons further away from the centerline of the crankshaft. In other words, a one-inch increase in connecting rod length will result in a one-inch increase in the distance between the crankshaft centerline and the top of a piston crown at top-dead-center. This will require a corresponding increase in the length of the cylinders in order to provide sufficient operating volume for the pistons. Again, the engine size and mass are increased. 
         [0054]    In contrast to the trade-offs inherent in the construction of a traditional crankshaft engine, a swash plate engine of the type depicted and shown herein can move the piston along a sinusoidal profile, thereby increasing the dwell time at top dead center, and therefore the performance potential of the engine. 
         [0055]    In addition to the kinematics advantages realized from the use of a swash plate, the movement of the pistons within the cylinders can be exploited to improve the performance and versatility of the engine, and particularly so in a two-stroke configuration, although the design is by no means limited to that configuration. As one of skill in the art can appreciate, alternate embodiments of the present invention may employ any of the power cycles known for producing power in the art of thermodynamics, including but certainly not limited to the four-stroke (Otto) cycle, the Diesel cycle, the Stirling cycle, the Brayton cycle, the Carnot cycle and the Seiliger (5-point) cycle, as examples. 
         [0056]    Engine  100  shown in  FIGS. 1-16  is a two-stroke configuration, having intake and exhaust ports disposed in the sidewalls of the cylinders  112 . The layout of the cylinder block  102  and intake and exhaust porting of engine  100  is shown in detail in  FIGS. 14-16 . Cylinder block  102  is secured to crankcase  104  by capscrews  250 . Cylinder block cover  254  is secured to crankcase  104  by capscrews  252 . Swash plate  108  is secured vertically within crankcase  104  between upper bearing race  256  and lower bearing race  258 . A set of connecting rod guides  260 , shaped and sized to receive and guide the connecting rods  114 , is disposed on top of the crankcase  104 . 
         [0057]    Air and fuel passes into each cylinder  112  through a set of intake ports  270 - 274 . Alternate embodiments may make use of more or fewer intake ports, as appropriate. In the embodiment shown in  FIGS. 14-16 , fuel is introduced to the intake charge by means of a single fuel injection port  290  disposed in each intake port  270 . Depending on the application, alternate embodiments may make use of one or more fuel injection ports disposed in one or more alternate locations, or may make use of carburetion or throttle-body fuel injection, as appropriate. As the piston crown descends on the downward power stroke, burned air/fuel mixture exits each cylinder  112  through one or more exhaust ports, such as ports  280 - 284 . 
         [0058]    The flow of intake through ports  270 - 274  and exhaust through ports  280 - 284  is controlled by the position and orientation of the piston  110  disposed within each cylinder  112 . While traditional two-stroke engine designs have been known to use the axial position of the piston to control the timing of intake and/or exhaust valving, engine  100  employs the axial position of each piston  110  in combination with the radial orientation of each position  110  to control the timing of intake and/or exhaust timing. Accordingly, engine  100  provides a significant degree of additional flexibility to engine designer and tuner as compared to the degree of flexibility available from previous designs. 
         [0059]      FIGS. 17-21  illustrate an embodiment of the engine wherein piston  110  is configured for additional lubricant circulation to reduce the aggregate coefficient of friction to mitigate or prevent overheating and improve engine performance. 
         [0060]      FIG. 17  shows an embodiment of piston  110  that is modified for improved cooling. Piston crown  152  has a transverse space  286  defined by spaced apart outer  288  and inner  290  walls by side wall  291  and extending generally along an axis  292  normal to the longitudinal axis  294  of the rod. Inner wall  290  includes an opening or passageway  298 , as shown best in  FIGS. 20 and 21 , that is preferably situated centrally in open communication with passageway  300  of rod  114 . From inner wall  290  about opening  298  is flange or sleeve  302  that extends inwardly for fitting engagement of rod  144  and may extend entirely or partially about the rod surface  304 . Where flange  302  extends partially about the rod surface it may comprise a series of flanges or a single flange for fixed attachment to rod  114 , as shown in  FIG. 17 . The flange  302  may be integral with the crown, or may be one or more separate components in fixed attachment by means known to one of ordinary skill in the art. Flange  302  comprises at least one opening  306  extending therethrough for the passage of lubricant between the rod passageway  300  and the transverse space  286  and the second end of the cylinder for heat transfer and cooling of piston  110  and engine  100 . In the embodiment illustrated in  FIG. 17 , piston skirt  150  includes an inward shoulder  308  that extends downwardly into a descending portion  310  that is substantially parallel to the outer surface of the flange  302  for fitting engagement therewith. As shown in  FIG. 17 , the descending portion may be substantially coterminative with the inwardly extending portion of the crown. The lower wall of the piston skirt, as shown in  FIG. 18 , is open and sized at its lower end to be received by the outer surfaces of rod guides  260   a . Within rod guides  260   a  is bearing  262  that is in sliding engagement with connecting rod  114 . 
         [0061]    The rod is substantially hollow throughout its length but comprises sufficient amount and type of material to maintain sufficient strength for its purpose with the space in open communication with the transverse space of the crown that allows lubricant or cooling agent to circulate between the piston space and the transverse space and via the crown holes into piston skirt space to cool the piston. In an embodiment the rod outer surface has a shape that is not prone to rotation about the longitudinal axis of the respective cylinder. 
         [0062]    Also contemplated is that engine  100  includes an exhaust chamber preferably centrally positioned within engine  100  that contains rotary valve  312 , as shown in  FIGS. 18-21 , that rotates about its longitudinal axis that is parallel to the central axis  294  and receives exhaust from one or more exhaust ports  280   a  from respective cylinders. 
         [0063]    Although this invention has been described in reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that this description encompass any such modifications or embodiments.