Patent Publication Number: US-9850759-B2

Title: Circulating piston engine

Description:
RELATED APPLICATION 
     This patent application claims the benefit of U.S. Provisional Application No. 61/748,553, filed on Jan. 3, 2013, entitled, “Circulating Piston Engine,” the contents and teachings of which are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     Conventional piston engines include multiple cylinder assemblies used to drive a crankshaft. In order to drive the crankshaft, each cylinder assembly requires fuel, such as provided by a fuel pump via a fuel injector. During operation, a spark plug of each cylinder assembly ignites a fuel/air mixture received from the fuel injector and causes the mixture to expand. Expansion of the ignited mixture displaces a piston of the cylinder assembly within a cylinder assembly housing to rotate the crankshaft. 
     SUMMARY 
     By contrast to conventional piston engines, embodiments of the present innovation relate to a circulating piston engine. In one arrangement, the circulating piston engine includes a housing that defines an annular bore extending about its outer periphery and a set of pistons disposed within the bore and secured to a drive mechanism or driveshaft. The engine also includes a set of valves that are moveably disposed within the bore, each valve being configured to define a temporary combustion chamber relative to a corresponding piston. 
     During operation, when disposed in a first position, each valve defines a combustion chamber relative to a corresponding piston, a fuel injector introduces a gas/air mixture into the chamber, and a spark plug ignites the mixture. Combustion of the mixture generates a corresponding force on each piston (e.g., along a direction that is substantially tangential to the annular bore along the direction of rotation of the drive mechanism) and propels the pistons forward within the annular bore. As each piston advances toward a subsequently disposed valve, each of the valves moves to a second position within the annular bore to allow each piston to rotate past the corresponding valve. Next, the engine repositions each valve within the bore to the first position to define the combustion chamber with the corresponding piston and the process begins again. Accordingly, as the set of pistons rotate around the perimeter of the engine, the drive mechanism generates a relatively large torque, such as an average torque of about 4500 ft-lbs. At ignition, the drive mechanism can generate a torque of about 10,000 ft-lbs. These torques are generated by the relatively large moment arm between each piston and the drive mechanism, as well as the 90° direction of the force applied to each piston. 
     In one arrangement, the annular bore defined by the engine housing has a relatively large circumference. During operation, when divided by the pistons, this results in a relatively long stroke distance utilizing a high percentage of the energy generated by combustion of the fuel/air mixture within the combustion chamber. Additionally, the substantially continuous motion of the pistons within the annular bore reduces the duration of time that each piston is exposed to the heat of combustion, thereby providing the engine with a relatively high thermal efficiency (e.g., relative to crankshaft-based engines). Also, the configuration of the fuel delivery system of the engine allows the fuel to be delivered to the engine in a process that is separate from, but parallel to, the combustion process. This creates, in effect, a single cycle engine where the combustion process is substantially continuous and where the power output of the engine can be increased (e.g., increased to a horsepower of about 685 @800 RPM) relative to conventional engines. Accordingly, the engine configuration results in the delivery of more precise fuel ratios, a more complete combustion of the fuel/air mixture, and shorter times at high temperatures compared to conventional piston engines. This can reduce the amount of contaminants generated by the engine and output as part of the exhaust and can increase the engine&#39;s efficiency such as to an efficiency of about 60%. 
     In one arrangement, embodiments of the innovation relate to an engine, such as a circulating piston engine. The engine includes a housing that defines an annular bore, a piston assembly, and a valve. The piston assembly is disposed within the annular bore and is configured to be coupled to a drive mechanism. The valve is configured to be intermittently disposed within the annular bore to define a combustion chamber relative to the piston assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects, features and advantages will be apparent from the following description of particular embodiments of the innovation, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of various embodiments of the innovation. 
         FIG. 1  illustrates an overhead, cross-sectional, schematic view of an engine having a piston assembly disposed in a first position within the housing, according to one arrangement 
         FIG. 2A  illustrates a partial sectional view of a portion of an annular bore of  FIG. 1 , according to one arrangement. 
         FIG. 2B  illustrates a partial sectional view of a portion of the annular bore of  FIG. 2A , according to one arrangement. 
         FIG. 3  illustrates an overhead, cross-sectional, schematic view of the engine of  FIG. 1  having a piston assembly disposed in a second position within the housing, according to one arrangement. 
         FIG. 4  illustrates a front view of an arrangement of a valve of  FIG. 1 , according to one arrangement. 
         FIG. 5  illustrates a rear view of the valve of  FIG. 4 , according to one arrangement. 
         FIG. 6  illustrates the valve of  FIG. 4  disposed in an engine, according to one arrangement. 
         FIG. 7A  illustrates an arrangement of a toggling mechanism coupled to the valve of  FIG. 4 , according to one arrangement. 
         FIG. 7B  illustrates a perspective view of a rocker arm of  FIG. 7A , according to one arrangement. 
         FIG. 8  illustrates an arrangement of a compressor of the engine of  FIG. 6 . 
         FIG. 9A  illustrates a top schematic view of an air intake assembly, according to one arrangement. 
         FIG. 9B  illustrates a perspective cutaway view of a rotatable plate of the air intake assembly of  FIG. 9A . 
         FIG. 9C  illustrates a schematic view of the air intake assembly and a fuel distribution assembly of  FIG. 9B . 
         FIG. 10  illustrates a perspective view of a rocker arm disposed between a valve and a splined barrel cam. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present innovation relate to a circulating piston engine. In one arrangement, the circulating piston engine includes a housing that defines an annular bore extending about its outer periphery and a set of pistons disposed within the bore and secured to a drive mechanism or driveshaft. The engine also includes a set of valves that are moveably disposed within the bore, each valve being configured to define a temporary combustion chamber relative to a corresponding piston. 
       FIG. 1  illustrates an overhead, cross-sectional, schematic view of a circulating piston engine  10 , according to one arrangement. The engine  10  includes a housing  12  that defines an annular channel or bore  14  and that contains a piston assembly  16  and a valve assembly  18 . 
     The annular bore  14  is disposed at an outer periphery of the housing  12 . While the annular bore  14  can be configured in a variety of sizes, in one arrangement, the annular bore  14  is configured as having a radius  15  of about twelve inches relative to an axis of rotation  21  of the piston assembly  16 . As will be described below, with such a configuration, the relatively large radius  15  of the annular bore  14  disposes the engine combustion chamber at a maximal distance from the axis of rotation  21  and allows the piston assembly to generate a relatively large torque on an associated drive mechanism  20 , such as a drive shaft, disposed at the axis of rotation. 
     The annular bore  14  can be configured with a cross-sectional area having a variety of shapes. For example, with reference to  FIG. 2B , in the case where a piston  24  of the piston assembly  16  is configured to define a generally rectangular cross-sectional area  25 , the annular bore  14  can also define a corresponding rectangular cross-sectional area  27 . In such an arrangement, the cross-sectional area  27  of the annular bore  14  is larger than the cross sectional area  25  of the piston  24  to allow the piston  24  to travel within the annular bore  14  during operation. 
     Returning to  FIG. 1 , in the arrangement illustrated, the piston assembly  16  is disposed within the annular bore  14  and is coupled to the drive mechanism  20  via a flywheel  22 . While the piston assembly  16  can include any number of individual pistons  24 , in the arrangement illustrated, the piston assembly  16  includes four pistons  24 - 1  through  24 - 4  disposed about the periphery of the flywheel  22 . While the pistons  24  can be disposed at a variety of locations about the periphery of the flywheel  22 , in one arrangement, opposing pistons are disposed at an angular orientation of about 180° relative to each other and adjacent pistons disposed at an angular orientation of about 90° relative to each other. For example, as illustrated, the first and third pistons  24 - 1 ,  24 - 3  are disposed on the flywheel  22  at about 180° relative to each other and the second and fourth pistons  24 - 2 ,  24 - 4  are disposed on the flywheel  22  at about 180° relative to each other. Additionally, the first and second pistons  24 - 1 ,  24 - 2  are disposed on the flywheel  22  at a relative angular orientation of about 90°, the second and third pistons  24 - 2 ,  24 - 3  are disposed on the flywheel  22  at a relative angular orientation of about 90°, the third and fourth pistons  24 - 3 ,  24 - 4  are disposed on the flywheel  22  at a relative angular orientation of about 90°, and the fourth and first pistons  24 - 4 ,  24 - 1  are disposed on the flywheel  22  at a relative angular orientation of about 90°. 
     During operation, the pistons  24  of the piston assembly  16  are configured to rotate within the annular bore  14 . As illustrated, the pistons  24  are configured to rotate within the annular bore  14  in a clockwise direction. However, it should be noted that the pistons can rotate within the annular bore  14  in a counterclockwise manner as well. Such rotation causes rotation of the drive mechanism  20 . 
     The valve assembly  18  includes a set of valves  30  configured to define combustion chambers  26  relative to the respective pistons  24  of the piston assembly  16 . For example, while the valve assembly  18  can include any number of individual valves  30 , in the arrangement illustrated, the valve assembly  18  includes valves  30 - 1  through  30 - 4  disposed within the annular bore  14  of the housing  12 . While the valves  30  can be disposed at a variety of locations about the periphery of the housing  12 , in one arrangement, opposing valves are disposed at an angular orientation of about 180° relative to each other and adjacent valves disposed at an angular orientation of about 90° relative to each other. For example, as illustrated, the first and third valves  30 - 1 ,  30 - 3  are disposed about the periphery of the housing  12  at about 180° relative to each other and the second and fourth valves  30 - 2 ,  30 - 4  are disposed about the periphery of the housing  12  at about 180° relative to each other. Additionally, the first and second valves  30 - 1 ,  30 - 2  are disposed about the periphery of the housing  12  at a relative angular orientation of about 90°, the second and third valves  30 - 2 ,  30 - 3  are disposed about the periphery of the housing  12  at a relative angular orientation of about 90°, the third and fourth valves  30 - 3 ,  30 - 4  are disposed about the periphery of the housing  12  at a relative angular orientation of about 90°, and the fourth and first valves  30 - 4 ,  30 - 1  are disposed about the periphery of the housing  12  at a relative angular orientation of about 90°. In such an arrangement, the relative positioning of the valves  30  of the valve assembly  18  corresponds to the relative positioning of the pistons  24  of the piston assembly  16 . 
     Each valve  30  of the valve assembly  18  is moveably disposed within the annular bore  14  to create a temporary combustion chamber  26  relative to a corresponding piston  24 . For example, during operation, each piston  24  of the piston assembly  16  rotates within the annular bore  14  and toward a valve  30  of the valve assembly  18 . Taking piston  24 - 1  and valve  30 - 1  as an example, and with reference to  FIG. 2A , as the piston  24 - 1  transitions within the annular bore  14  from a distal position to a proximal position relative to the corresponding valve  30 - 1 , the valve  30 - 1  is disposed in a first position relative to the annular bore  14 . In the first position, the valve  30 - 1  is at least partially withdrawn from the travel path of the piston  24 - 1  within the annular bore  14  to allow the piston  24 - 1  to advance along its travel path. With reference to  FIG. 2B , when the piston  24 - 1  reaches a given location within the annular bore  14  (e.g., once the piston  24 - 1  has passed the valve  30 ), the valve  30 - 1  moves to a second position relative to the annular bore  14  (e.g., to a closed position), such as illustrated. With such positioning, the valve  30 - 1  defines the combustion chamber  26 - 1  relative to the piston  24 - 1  and is configured as a bulkhead against which combustion can work to produce power. 
     For example, with each valve  30  disposed in a closed position as indicated in  FIG. 1 , a fuel injector  32  then delivers a fuel-air mixture  34  into the associated combustion chambers  26  which can then be ignited by an ignition device (not shown) such as a spark plug. As the ignition devices ignite the fuel-air mixture  34  in all four of the combustion chambers  26 - 1  through  26 - 4  in a substantially simultaneous manner, the expansion of the fuel-air mixture  34  against each valve  30 - 1  through  30 - 4  generates a load  36  on each of the corresponding pistons  24 - 1  through  24 - 4  to propel each piston  24 - 1  through  24 - 4  along the rotational travel path defined by the annular bore  14 . 
     With reference to  FIG. 3 , each of the pistons  24 - 1  through  24 - 4  travels within the bore  14  along a relatively large stroke distance, such as a distance of between about 12 inches and 15 inches, toward the next valve  30 . At a certain point in the bore  14 , such as at the end of a stroke length  13  as illustrated in  FIG. 1 , each piston  24  passes a corresponding exhaust port  38  (i.e., disposed proximal to the subsequent valve  30 ) which vents the spent gas contained in the chamber  26  to the atmosphere. For example, as piston  24 - 1  passes the exhaust port  38 - 1 , spent gas contained in the chamber  26 - 1  between the piston  24 - 1  and the valve  30 - 1  can exit the chamber  26 - 1  via the exhaust port  38 - 1 . 
     The exhaust ports  38 , in one arrangement, are configured as passive ports which are open to the atmosphere and which do not require mechanical components. In one arrangement, each exhaust port  38  is configured as being relatively large to provide efficient exhausting to the engine  10 . For example, the stroke distance between the piston  24  and valve  30 , such as a stroke distance of between about 12 inches and 15 inches, can form part of each exhaust port  38  to increase the overall length of the port  38 . 
     Additionally, as each piston  24  approaches the subsequently disposed valve  30 , each valve  30  moves from the second, closed position ( FIGS. 1 and 2B ) to the first position ( FIGS. 3 and 2A ) relative to a corresponding piston  24 . For example, as the piston  24 - 1  approaches the valve  30 - 2 , the valve  30 - 2  is at least partially withdrawn from the bore  14  to allow the piston  24 - 1  to move past the valve  30 - 2 . Once each of the pistons  24  have translated to a location distal to the corresponding valves  30 , the corresponding valves  30  are moved to the first position and the process begins again. Accordingly, during operation, the engine  10  can generate up to sixteen combustion events per revolution (i.e., each of four pistons  24  experiencing up to four combustion events in a single revolution), thereby causing the piston assembly  16  to rotate the drive mechanism  20 . 
     In use, the pistons  24  and valve assembly  16  are disposed at the outer perimeter of the engine housing  12 , such as at distance of about twelve inches from the drive mechanism  20 . With the combustion force applied to the pistons  24  along a direction that is tangent to the direction of rotation and perpendicular to the distance  15  from the drive mechanism  20 , such combustion force can maximize torque on the drive mechanism  20 . Additionally, the relatively long stroke path of the pistons  24 , the presence of the exhaust ports  38 , and the ability of the engine  10  to customize the number of combustion events generated in the bore  14  can enhance the performance of the engine  10 . For example, the engine  10  can produce a relatively large amount of continuous power (e.g., a horsepower of about 685 @800 RPM) with a relatively high torque (e.g., an average torque of about 4500 ft-lbs) and efficiency (e.g., an efficiency of about 60%) relative to conventional engines having an efficiency of about 25-30%. 
     In one arrangement, the operation of the engine  10  can considerably reduce pollutants compared with current engines. For example, the relatively long stroke distance, among other factors, can reduce unburnt hydrocarbons and carbon monoxide contained in the combustion chamber  26 . Oxides of nitrogen should also be reduced since the amount formed during combustion is proportional to temperature and dwell times. The rapid and continuous motion of the piston  24  within the bore  14  can reduce their formation, as dwell times will be reduced. 
     As indicated above, the engine  10  can generate relatively large amounts of torque (e.g., 15 times the torque generated by conventional engines). In conventional piston engines, complex six-speed (and greater) transmissions are needed to multiply the engine&#39;s torque for adequate performance, which add to the weight, expense, and complexity to the transmissions. However, because the engine  10  described above generates a relatively higher amount of torque, the engine requires fewer gear ratios than conventional engines and, hence, utilizes a lighter and less expensive transmission. 
     It should be noted that the relatively high torque generated by the engine  10  can be managed by adjustment of the combustion events (i.e., the firing sequence of the pistons  30  and detonation mechanisms) within the engine  10 . For example, each piston  24  can experience four combustions per revolution such that the entire piston assembly  16  experiences a total of sixteen combustions per revolution. In order to control the power and output torque of the engine  10  as necessary, the engine  10  can fire anywhere from one to sixteen times per revolution. For example, the combustion chambers  26  are arranged around the periphery and can be fired independent from each other. This allows firing of a combustion event from one to sixteen times per revolution to adjust the velocity of the pistons  24  within the annular bore and to adjust the power or output torque generated by the engine  10 . Such a configuration of the engine  10  contrasts the use of a throttle in conventional engines, which manages flow of air and is relatively less efficient. 
     As indicated above, each valve  30  of the valve assembly  18  is moveably disposed within the annular bore to create a temporary combustion chamber  26  relative to a corresponding piston  24 . The valve assembly  18  and valves  30  can be configured in a variety of ways to provide such temporary combustion chamber creation.  FIGS. 4 through 7  illustrate one arrangement of a valve assembly  118  having a valve  130  configured to reciprocate within the bore  14 . 
     In one arrangement, the valve assembly  118  includes a housing  129  with the valve  130  being rotatably coupled to the housing  129 . The valve  130  is configured to pivot within the housing  129  between a first position that allows a piston  24  to travel within the annular bore  14  past the valve  130  and second position that defines the combustion chamber  26  relative to the piston  24 . For example, the valve  130  is configured with a notch that defines a channel  135  relative to the annular bore  14  of the housing  10 . When the valve  130  is disposed in the first position, as indicated in  FIGS. 4 and 5 , the channel  135  is configured to allow a piston  24  to travel within the annular bore  14  between a first location proximal to the valve assembly  118  (such as indicated by valve  30 - 1  relative to piston  24 - 4  in  FIG. 3 ) and a second location distal to the valve assembly  118 . As the valve  130  pivots or rotates within the housing  129  along direction  139 , a bulkhead portion  137  of the valve  130  enters the annular bore  14  to define the combustion chamber  26  with the piston  24 , as illustrated in  FIG. 6 . 
     In one arrangement, a portion of the fuel injector  32  of the engine  10  is integrally formed with the valve  130 . For example, with reference to  FIGS. 4-6 , the housing  129  includes a fuel source port  133  disposed in fluid communication with a set of openings  141  (see  FIG. 7A ) defined by the valve  130  and with a fuel source and an air source or air intake assembly  250  (see  FIGS. 6 and 9A-9C ). During operation, the valve  130  is configured to combine fuel from the fuel source and air from the air source  250  into a fuel-air mixture within the combustion chamber  26 , as illustrated in  FIG. 6 . 
     In one arrangement, the rotation of the valve  130  within the housing  129  can control delivery of the fuel and air from the fuel source port  133  to the set of openings  141  of the valve  130  and, subsequently, to the combustion chamber  26 . For example, when the valve  130  is disposed in the first position, as indicated in  FIGS. 4 and 5 , the set of openings  141  can be aligned with a wall of the housing  129  to fluidly decouple the set of openings  141  from the fuel source port  133 . In such an arrangement, the wall housing  129  blocks the delivery of fuel and air from the fuel source and air source  250  to the openings  141 . Accordingly, as the piston  24  rotates past the valve  130 , the valve  130  cannot deliver fuel or air into the annular bore  14 . When the valve  130  rotates to the second position as illustrated in  FIG. 6 , the set of openings  141  align with and fluidly couple to the fuel source and air source  250  via the fuel source port  133 . Accordingly, with such positioning, the valve  130  can direct the fuel and air into the combustion chamber  26  defined between the piston  24  and the valve  130 . 
     Actuation of the valve  130  between the second, closed position to the first, open position utilizes a synchronous actuation mechanism to limit or prevent mechanical contact between the circulating piston  24  and the valve  130  during operation. Conventional engines utilize a cam and cam follower to drive a valve to an open position and a heavy-duty return spring to move the valve to a closed position. The return springs in conventional engines, however, can cause problems due to resonance in the return spring at high operating frequencies. When the operating frequency of the engine matches the natural frequency of the spring, resonance occurs in the spring which can dispose the valve in a position other than the position prescribed by the motion of the cam. 
     Additionally, resonance can cause a phenomenon known as valve float. In the case of resonant oscillation, the return spring does not have enough stored energy to accelerate the mass of the valve. As a result, the valve effectively floats in a substantially stationary position. Accordingly, as the cam follower leaves and recontacts the cam surface, contact between the cam follower and the cam face generates a contact stress, known as von Mises stress. If the contact stress exceeds the yield strength of the cam surface, gaulling of the cam surface can occur. 
     While the valve  130  can be actuated within the housing  129  in a variety of ways, in one arrangement, to minimize issues caused by possible resonance of the valve, the valve assembly  118  includes a toggling assembly  155 , as shown in  FIGS. 4, 5, and 7A , configured to toggle the valve  130  within the housing  129 . The toggling assembly  155  is configured to exert positive loads on the valve  130  (i.e., apply a push/push motion on opposing ends of the valve  130 ) when positioning the valve  130  between the first and second positions. For example, with reference to  FIG. 7A , the toggling assembly  155  can include a first arm  157  coupled to a first end  158  of the valve  130  and a second arm  159  coupled to a second end  160  of the valve  130 . During operation, the first arm  157  is configured to generate a first, linear, positive load  162  on the first or proximal end  158  of the valve  130  along a positive displacement direction to pivot the valve  130  toward the first position, as illustrated in  FIGS. 4 and 5 . Further during operation, the second arm  159  is configured to generate a second, linear, positive load  164  on the second or distal end  160  of the valve  130  along the positive displacement direction to pivot the valve  130  toward the second position, as illustrated in  FIG. 6 . 
     The toggling assembly  155  can be actuated in a variety of ways. In one arrangement, as illustrated in  FIG. 7A , the arms  157 ,  159  of the toggling assembly  155  are coupled to a cam assembly  165  that includes a barrel cam, such as a conjugate splined barrel cam  170 , a rocker arm  174 , and a toggle element  176  coupled between the rocker arm  174  and the first and second arms  157 ,  159 . 
     The conjugate splined barrel cam  170  defines a spline profile  180  for each valve  130 . The profile  180  of the cam  170  includes a rise portion  182 , a dwell portion  186 , and a fall portion  184  which defines the relative movement of the valve  130  during operation. During operation, as the cam rotates about a longitudinal axis  172 , the profile  180  imparts an oscillating motion to the valve  130  through the rocker arm  174  and toggle element  176 . 
     The rocker arm  174  is configured to translate the motion of the profile  180  into a reciprocation motion of the toggle element  176 . For example, the rocker arm  174  includes a first cam follower  188  and a second cam follower  190 , each disposed in proximity to the profile  180  of the cam  170 . The rocker arm  174  includes a sliding/pivot joint  192  which actuates the toggle element  176  about longitudinal axis  194  in response to the motion of the rocker arm  174 . Because the total angular motion of the toggle element  176  is bisected evenly, when one arm or push rod  157  moves in one direction, the other arm or push rod  159  is displaced by an equal amount in the opposite direction. Cam assembly  165 , accordingly, achieves substantially zero backlash during operation when opening and closing the combustion valve  130 . 
     During operation, as the conjugate splined barrel cam  170  rotates about an axis  172 , a spline profile or element  180  of the cam  170  actuates the arms  157 ,  159  to drive the valve  130  between the first and second positions. For example, the cam profile  180  drives the valve  130  to an open position and remains open as the piston  24  passes by and then drives the valve  130  to the closed position when the piston  24  has passed. 
     In one arrangement, to increase the longevity and lower frictional losses of the toggling assembly  155  and the cam assembly  165 , all joints can be configured as roller bearings that can be either pressure lubricated or disposed within an oil bath. In one arrangement, the two cam followers  188 ,  190  that capture the cam profile  180  are formed from a compliant material to allow for tolerance mismatch in the rocker arm  174 , the two cam followers  188 ,  190 , and the relative pivot position of the rocker arm  174  during operation. 
     Although tolerance could be held to the standards to minimize or prevent backlash, such standardization can add cost to manufacturing process. In one arrangement, to limit the use of tolerance standards, and with reference to  FIG. 7B , the second cam follower  190  is secured to an oscillating lever  195  via a diamond-shaped pin  196 . The oscillating lever  195 , in turn, is coupled to the rocker arm  174  via a spring mechanism  197 . The diamond-shaped pin  196  allows relatively small movements of the second cam follower  190  in one direction  198  while maintaining the position of the first cam follower  188 . In the application shown in  FIG. 7B , the diamond-shaped pin  196  allows a distance  199  between the cam followers  188 ,  190  to be constantly adjusted by a compressive force, but maintains a radial position of the second cam follower  190  relative to its own pivot point. Accordingly, with the first cam follower  188  and the second cam follower  190  configured to apply a preload force against the spline profile  180 , the rocker arm  174  minimizes the use of tolerance standards as part of the cam assembly  165 . 
     The absence of springs in toggle assembly  155  and the cam assembly  165  insures that the valve position is controlled strictly by the cam profile  180  which is important to the functionality of the engine  10  and can limit or prevent any contact between the circulating piston  24  and the valves  130 . In the event contact were to occur due to a statistical failure, the valve  130  is designed to move in the same direction as the circulating piston  24  and would most likely be disposed in a closed position in the event of failure. 
     Conventional engines utilize four stages or cycles to produce power. These cycles include an intake cycle which provides the intake of air and fuel through a system of valves created by piston retraction, a subsequent compression cycle to compress the air and fuel, an ignition/combustion/power cycle, and an exhaust cycle to forcibly exhaust combustion byproducts through a separate valve system. The four stages are performed in a serial fashion by a piston contained within a cylinder of the engine. 
     In conventional piston engines, the pressure of the hot gasses created by the combustion of the air and fuel mixture contained within the cylinder can create blowby where the hot gasses and their corrosive byproducts are forced past the piston rings into the interior of the engine. As the gasses and byproducts pass into the engine, they can burn a portion of the lubricating oil contained within the cylinder, thereby adding to pollutant creation and corruption of the oil supply. As a result, conventional engines require relatively frequent oil changes. Additionally, conventional piston engines do not allow for relatively high compression ratios because of the resulting knocking/autoignition caused by the relatively long dwell times which can damage the piston and cylinder walls. 
     With reference to  FIG. 8 , the engine  10  can include a compressor  200  configured to perform an intake cycle to deliver air and fuel into the engine  10  and a compression cycle to compress the air and fuel. The compressor  200  performs these cycles independent from the power and exhaust cycles performed by the valve and piston assemblies  16 ,  18 . By separating the compression process from the combustion process, as found in conventional engines, the compressor  200  allows the engine  10  to start operation with the use of air pressure only. For example, the compressor  200  can be configured to insert compressed air from a reservoir into the combustion chamber  26  between the piston  24  and the closed previous valve  30 . Such injection moves the piston  24  to the next point in the annular bore  14  for reignition. To insure the proper location of the piston  24 , a small brake can be applied to the flywheel  22  when the engine  10  is turned off to insure proper positioning of the piston  24  for restart. Accordingly, the use of the compressor  200  as part of the engine can minimize or eliminate the need for a starter motor, as found in conventional engines, and can reduce the overall, size, weight, and cost associated with the engine  10 . 
     In one arrangement, the compressor operates synchronously with the engine. For example, the compressor  200  is connected to a drive mechanism  20  powered by the engine  10  through a transmission system  202 . The transmission system  202  can be configured as a belt and gear system that includes a set of belts  204 - 1 ,  204 - 2  and corresponding gears  206 - 1 ,  206 - 2 . As illustrated, the first belt  204 - 1  is operatively coupled to the drive mechanism or drive shaft  20  of the engine  10  and to the first gear  206 - 1 , the second belt  204 - 2  is operatively coupled to the second gear  206 - 2  and to a compressor shaft  207 , and the first gear  206 - 1  is operatively coupled to the second gear  206 - 2  via shaft  209 . In one arrangement, to cover a speed range of between about 0 to 155 miles per hour (mph), a gear ratio (i.e., including the rear and transmission rears) of between about 1.00:1 (e.g., providing about 60 mph) and 2.57:1 (e.g., providing about 155 mph) can be utilized. Such a configuration can utilize a four-speed transmission with a rear gear ratio of 1:1 and a first gear ration also 1:1. This compares to a conventional drive train having a six-speed transmission of overall ratios of 12.23:1 in first gear (e.g., 30 mph max) to 2.18:1 in sixth gear (e.g., 155 mph max). 
     The transmission system  202  is configured to alter a ratio of compressor speed to engine speed to control a volume of compressed air generated by the compressor  200  and to control a compression ratio associated with the air and fuel. For example, as the transmission system  202  receives rotational input from the drive shaft  20 , the system  202  applies a rotational output on the compressor shaft  207  to rotate the shaft  207  at a rate that is faster than the rotational rate of the drive shaft  20 . This produces a high volume of air at a relatively high pressure. Accordingly, the transmission system  202  allows the compressor  200  to operate at a variety of ratios/speeds to optimize performance. 
     During operation, the compressor  200  generates relatively highly pressurized air which is then mixed with fuel from an injector close to the combustion chamber  26 . This allows the input of the air/fuel mix into the combustion chamber  26  at very high pressures, such as pressures of between about 150 and 200 pounds per square inch (psi). Accordingly, the air/fuel mix enters the combustion chamber  26  at a relatively high velocity to create turbulence within the combustion chamber  26  which promotes a mixture of the air and fuel, as well as a short input duration (e.g., as measured in fractions of milliseconds). The high velocity and pressure of the air/fuel mix promote rapid combustion which contributes to the engine&#39;s  10  relatively high efficiency. 
     As indicated above, the compressor  200  is configured to perform two of the four stages or cycles utilized by an engine during operation, separate from the combustion process. Such a configuration allows the circulating pistons  24  in the bore  14  to exclusively perform the third stage (i.e., producing substantially continuous power) during operation. The engine  10  performs the fourth exhaust stage passively with a large, valveless port associated with the bore  14  and open to the air treatment system and atmosphere. When combustion and expansion is complete, the piston  24  passes the exhaust opening  38  and the spent gas within the chamber  26  is expelled from the engine. The compressor  200  is physically and thermally isolated from the combustion process. Accordingly, the compressor  200  does not experience blowby which, in conventional piston engines relates to the passage of combusted gases past the piston rings and into a crankcase. Traditional blowby causes the engine to accumulate contaminated exhaust gas that requires treatment before exhausted to the atmosphere. In addition, in conventional piston engines, the mixing of contaminated exhaust gases with the oil stored in the case significantly shortens the oil life causing more frequent oil changes. This oil itself must be treated before disposal or reuse. 
     With reference to  FIG. 6 , and as indicated above, valve  130  is configured to input the fuel-air mix from a fuel distribution assembly  262  close to the combustion chamber  26 .  FIGS. 9A through 9C  illustrate an example schematic representation of an air intake assembly  250  and fuel distribution assembly  262 . 
     As illustrated, the air intake assembly  250  includes a housing  252  having an air intake port  254  and an air output port  258 . The air intake port  254  is configured to receive air from an air source, such as a high pressure air source. The air output port  258  is selectively disposed in fluid communication between the housing volume  257  and the fuel distribution assembly  262 . 
     The air intake assembly  250  further includes a drive assembly  270  that is configured to provide selectable communication between the air output port  258  and the interior volume  257  of the housing  252 . For example, the drive assembly  270  includes a shaft  272  disposed in operational communication with the engine  10  and gear  274 , such as a worm gear, disposed at an end of the shaft  272  and a plate  278  that is rotatably coupled to the housing  252 . The gear  274  is disposed in operational communication with a corresponding set of teeth  276  disposed about an outer periphery of the plate  278 . The plate  278  is configured to rotate about a longitudinal axis  280  within the housing  252  in response to axial rotation of the drive assembly  270 . For example, during operation, rotation of the shaft  272  and the gear  274  about longitudinal axis  282  in a clockwise direction causes the plate  278  to rotate within the housing  252  in a counterclockwise direction about longitudinal axis  280  within the housing  252 . Additionally, the plate  278  defines an aperture  282  that is configured to selectively allow fluid communication between the port  258  and the housing volume  257 , as described in detail below. 
     With reference to  FIG. 9C , located in proximity to the air intake assembly  250  is the fuel distribution assembly  262 . The fuel distribution assembly  262  is configured to allow mixing of the fuel and air within the assembly housing  263 . Attached to the housing  263  is at least one fuel injector  32 . 
     During operation, the plate  278  disposes the aperture  282  along a rotational path  264 , as indicated in  FIG. 9A . As the plate  278  rotates along a counterclockwise direction toward the output port  258 , the plate  278  positions the aperture  282  along the path  264 . With such positioning, the plate  278  blocks output port  258  and from the housing volume  257  to minimize or prevent fluid communication there between. Accordingly, the housing volume  257  can receive relatively high pressure air via the air intake port  254 . 
     As the aperture  282  approaches a first open position  266 , the fuel injector  32  injects fuel into the housing  263  of the fuel distribution assembly  262 . As the plate  278  continues to rotate along the counterclockwise direction, the plate  278  disposes the aperture  282  in a first open position  266  which aligns the aperture  282  with the air output port  258 . With such positioning, immediately following fuel injection, compressed air from assembly  250  is transported through port  258  of assembly  250  and into the fuel distribution assembly  262  to mixes the air with the suspended fuel  267 . This mixture then flows through flexure valves  265  and into openings  141  of the valve  130 , as indicted in  FIG. 6 . A bleed line  256  attached to an intake system of the compressor  200  draws excess air, reducing the high pressure in assembly  262  permitting operation of the fuel injector  32  for the next cycle which operates at lower pressure. 
     Following the delivery of the air to the fuel distribution assembly  262 , the plate  278  rotates the aperture  282  counterclockwise past the air output port  258  to allow introduction of pressurized air into the volume  257  for a subsequent fuel distribution cycle. 
     While various embodiments of the innovation have been particularly shown and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the innovation as defined by the appended claims. 
     For example, as described above, the piston assembly includes four pistons and the valve assembly includes four valves. Such description is by way of example only. In one arrangement, the piston assembly can include a first piston and a second piston, the first piston disposed within the annular bore at a position that is substantially 180° from the second piston. Additionally, the valve assembly can include a first valve disposed at a first location within the housing and a second valve disposed at a second location within the housing, the second valve being disposed along the annular bore at a position that is substantially 180° relative to the first valve. 
     As indicated above, the valve assembly  118  includes a toggling assembly  155 , as shown in  FIGS. 4, 5, and 7A , configured to toggle the valve  130  within the housing  129 . As described, the arms  157 ,  159  of the toggling assembly  155  are coupled to a cam assembly  165  that includes a barrel cam, such as a conjugate splined barrel cam  170 , a rocker arm  174 , and a toggle element  176  coupled between the rocker arm  174  and the first and second arms  157 ,  159 . During operation, the first arm  157  is configured to generate a first, positive load  162  on the first end  158  of the valve  130  along a positive displacement direction to pivot the valve  130  toward the first position and the second arm  159  is configured to generate a second, positive load  164  on the second end  160  of the valve  130  along the positive displacement direction to pivot the valve  130  toward the second position. Such description is by way of example only. In one arrangement, the toggling assembly is configured with a reduced number of moving parts that extends a connection between the valve  130  and the cam  170  along an axis of rotation of the valve  130 . 
     For example, with reference to  FIG. 10 , the toggling assembly  255  includes a valve support  231  extending along a longitudinal axis  233  of the valve  130  between the valve  130  and the rocker arm  174 . A first end  235  of the valve support  231  is coupled to the valve  130  while a second end of the valve support  237  is slidably coupled to the rocker arm  170  via a sliding/pivot joint  192 . While the valve support  231  can be configured in a variety of ways, in one arrangement, the valve support  231  is configured as a substantially cylindrical, tubular structure. 
     During operation, as the conjugate splined barrel cam  170  rotates about the axis  172 , the spline profile or element  180  of the cam  170  oscillates the rocker arm  174  in both a clockwise and counterclockwise direction about an axis of rotation  239 . In response to the oscillation of the rocker arm  174 , the sliding/pivot joint  192  exerts a first rotational load  241  and an opposing second rotational load  243  on the valve support  231  to oscillate the valve support  231  and the valve  130  about longitudinal axis  233 . Such oscillation positions the valve  130  between a first (e.g., open) position and a second (i.e., closed) position within the valve housing. 
     Use of the valve support  231  provides the toggling assembly  255  with a relatively low moment of inertia which, in turn, allows the rocker arm  174  to toggle the valve  130  within the valve housing at a relatively high speed. Additionally, because the valve support  231  has relatively few parts, the valve support  231  reduces the possibility of the toggling assembly  255  failing during operation. 
     Furthermore, the valve support  231  provides the toggling assembly  255  with a relatively long life. For example, during operation as the piston  24  approaches the valve  130 , the valve  130  must move to an open position (i.e., out of the piston&#39;s path) and then back to a closed position in a relatively short amount of time. Once the toggle assembly  255  moves the valve  130  to a closed position, the valve  130  defines a combustion chamber relative to the piston  24  and the gas pressure within the chamber builds at a relatively high rate. The gas pressure within the combustion chamber creates not only a force that propels the piston  24  forward, but an equal and opposite force on the valve  130  itself. With the configuration of the valve support  231  as a substantially cylindrical, tubular structure, the valve support  231  has a relatively large stiffness which increases the overall stiffness of the valve assembly and minimizes failure. 
     As indicated above, each valve  30  of the valve assembly  18  is moveably disposed within an annular bore to create a temporary combustion chamber  26  relative to a corresponding piston  24 . For example, with reference to  FIG. 2B , when the piston  24 - 1  reaches a given location within the annular bore  14 , the valve  30 - 1  moves to a second position relative to the annular bore  14 . With such positioning, the valve  30 - 1  forms the combustion chamber  26 - 1  relative to the piston  24 - 1  and is configured as a bulkhead against which combustion can work to produce power. In one arrangement, the size of the combustion chamber  26  can be altered during operation to adjust the power output or efficiency of the engine. For example, the volume of the combustion chamber  26  can be decreased or increased by varying the duration of the fuel input process to the combustion chamber  26  and by adjusting (e.g., delaying) the ignition timing accordingly. In the case where the volume of the combustion chamber  26  is increased, the engine can include a second spark plug (not shown) located adjacent to the relatively larger combustion chamber  26  to accelerate combustion in the enlarged chamber. 
     It should be noted that the walls of the combustion chamber  26  and the direction of introduction of fuel relative to the valve can be modified to create a variety of geometric travel paths for the air/fuel mixture. For example, the walls of the combustion chamber  26  and the direction of fuel introduction can define a circular or other geometry to accelerate ignition and combustion effectiveness. 
     As indicated above, in order to control the power and output torque of the engine  10  as necessary, the engine  10  can fire anywhere from one to sixteen times per revolution. In one arrangement, the engine  10  can be configured to alternate the firing order of the combustion chambers  26  to reduce the operating temperature of the engine  10 . For example, with reference to  FIG. 1 , in the case where the engine  10  has accelerated to a particular drive mechanism  20  velocity, the engine  10  can require firing of only two combustion chambers  26  during a revolution of the piston assembly  30  within the engine  10  to maintain the velocity. To minimize the engine temperature, in a first revolution cycle, the first  26 - 1  and third  26 - 3  combustion chambers can be fired while in a second revolution cycle, the second  26 - 2  and fourth  26 - 4  combustion chambers can be fired. When certain combustion chambers  26  are not fired, relatively low temperature air flows through those combustion chambers as well through the annular bore  12 , thereby reducing the operating temperature of the engine  10 . This allows a leaner fuel-air mixture to be utilized during operation to improve engine efficiency and air quality.