Patent Publication Number: US-7219631-B1

Title: High torque, low velocity, internal combustion engine

Description:
RELATED APPLICATION 
   This application is a continuation of U.S. patent application Ser. No. 10/371,652, Filed on Feb. 24, 2003 now abandoned and is related to a commonly-owned, US. patent application Ser. No. 10/112,145, entitled “Propulsion System for Vertical Take-Off and Landing (VTOL) Vehicles”. 

   TECHNICAL FIELD 
   This invention is directed to internal combustion engines, and more particularly, to internal combustion engines employing cam means for converting linear motion of a piston/cylinder into rotational motion of an output drive shaft, and still more particularly, to a new and useful internal combustion engine which maximizes energy conversion, eliminates the need for intermediate speed reduction devices, e.g., speed reducing transmissions, improves performance, enhances reliability and reduces mechanical complexity. 
   BACKGROUND OF THE INVENTION 
   Designers of power output devices, e.g., automobile, aircraft and locomotive engines, are faced with a myriad of competing design criteria that result in various design compromises. For example, if it is desirable to optimize power output, a compromise in engine torque is often necessary. Similarly, if one desires optimal energy conversion, e.g., specific fuel consumption, a designer must choose an appropriate air-standard combustion cycle to match this requirement. In yet other examples, if it is desirable to optimize horsepower and torque, one may need to accept weight and/or fuel consumption penalties. 
   While there are literally thousands of internal combustion engine designs and variations thereof, all employ certain fundamental or basic principles. These include the intake of a combustible mixture, e.g., oxygen and gasoline, into a working area, compression of the combustible mixture, ignition of the mixture to effect its expansion, capturing the energy of the expansion to produce work, and expelling combustion by-products into an exhaust system so as to prepare the working area for a subsequent cycle. 
   Internal Combustion Engines (ICEs) 
   Commercially successful internal combustion engines include reciprocating-piston, rotary, and gas-turbine engines. Following is a brief discussion of each followed by the advantages and disadvantages of each. Applications of each are also discussed. 
   Traditional reciprocating internal combustion engines employ the reciprocating motion of a piston/cylinder to perform the functions described above. Linear motion of the piston is translated into rotational motion by means of a piston rod that is articulately mounted to the underside of the piston at one end thereof and pivotally mounted at the other end to an eccentric portion of a crankshaft. Generally, these internal combustion engines employ the Carnot two-stroke, Otto four-stroke or Diesel two and/or four-stroke air-standard cycles. 
   The Carnot two-stroke engine typically employs a piston/cylinder arrangement wherein the cylinder comprises inlet and exhaust ports located on opposite sides of the cylinder walls. The inlet port is located slightly above the lowest point of piston travel, e.g., bottom dead center, and the exhaust port is located on the opposing side about a midpoint relative to piston travel. The combustible mixture is first introduced into the cylinder chamber as the piston uncovers the inlet port. The downward motion of the piston from the prior stroke, causes the combustible mixture (located within the housing) to be pressurized thus being forced into the cylinder chamber. As the piston moves upwardly and past the exhaust port, the combustible mixture is compressed and ignited upon reaching the top of the piston&#39;s stroke, i.e., top dead center. The expansion of the combustible mixture produces a downward power stoke and, upon passing the exhaust port, begins to be expelled from the cylinder chamber. As the piston travels downward yet further, the combustible mixture is pressured by the underside of the piston (traveling downwardly) and is injected into the cylinder as the piston passes the inlet port. This injection of newly-introduced combustible mixture further augments the expulsion of exhaust gases through the exhaust port. The Carnot two-stroke produces a power stroke for every two strokes of the piston, or once per revolution, i.e., of the drive shaft. 
   The Otto four-stroke engine typically employs a piston/cylinder arrangement wherein the inlet and exhaust ports are located at the top or uppermost portion of the cylinder and are operated, i.e., opened and closed, by means of cam-driven valves. The combustible mixture is first introduced upon opening the inlet port whereby the downward motion of the piston generates a vacuum for drawing the combustible mixture into the cylinder. The next stroke is the compression stroke, wherein the inlet and exhaust valves are both closed and the combustible mixture is compressed as the piston traverses upwardly. At or near the top of the piston stroke, the air-gas mixture is ignited thus initiating its expansion and downward motion of the piston. Upon completion of the downward or power stroke, the exhaust port is opened such that the subsequent upward stroke of the piston expels the combusted gases outwardly into an exhaust manifold. The Otto four-stroke cycle produces a power stoke for every four stokes of the piston, or once every two revolutions of the drive shaft. 
   More recent innovations include the Wankel Rotary engine which employ the eccentric motion of a polygonal-shaped rotor within a substantially elliptically-shaped, or more accurately, a epitrochoidally-shaped housing or chamber. The apexes of the polygonal-shaped rotor create discrete chambers which, upon rotation of the rotor within the housing, pass inlet ports, ignition spark plugs and exhaust ports. More specifically, as the rotor passes the inlet port, the combustible mixture is introduced within one of the chambers. As this chamber rotates approximately 90 degrees, the mixture is compressed against a wall of the epitrochoidally-shaped housing. Ignition or spark plugs are located at this angular position and, upon ignition, the combustible mixture expands causing the rotor to be driven approximately 120 degrees within the housing. An exhaust port is located at the next rotational position and the combusted gases are expelled from the chamber. Similar to the compression stage of the Wankel cycle, the chamber is caused to be reduced in volume, i.e., against the wall of the epitrochoidally-shaped housing, thereby expelling the exhaust gases outwardly. 
   In conventional turbine engines, a compressor section is used to compress air into a combustion chamber. Fuel is introduced into the chamber and ignited to expand the air-gas mixture. Turbine vanes capture the energy of the expanded air-gases to turn a turbine shaft which also drives the compressor section to continue the combustion cycle. Generally, this form of internal combustion engine employs the Brayton air-standard cycle. From its brief description, it will be appreciated that the turbine engine is, perhaps, the most elegant, however, it too has disadvantages which limits its application. 
   Advantages/Disadvantages &amp; Practical Applications of Reciprocating Piston ICEs 
   The following is a brief examination of reciprocating piston ICEs in terms of their properties, performance, and practical applications. Inasmuch as the Wankel rotary and turbine engines are not widely employed or have specific/limited applications, these will only be mentioned in terms of there need for gear reduction apparatus to lower output velocities to useable speeds. Furthermore, these engine designs represent a significant departure from the elements and teachings of this invention. 
   A two stroke air-standard cycle (or Carnot Cycle) delivers a power stoke with each revolution as compared to the four-stroke cycle which delivers a power stroke with every two revolutions. Consequently, reciprocating ICEs employing a two stroke cycle can deliver twice the power of a four stroke. Two stroke engines do not require valves and the associated mechanisms for the intake of fuel and exhaust of combusted gases. Four stroke engines, on the other hand, require a complex array of cam-driven valves for intake and exhaust. ICEs employing a two stroke cycle can operate at any orientation, which can be important in applications wherein the powered-vehicle or device pitches or rolls such as an acrobatic fixed-wing aircraft, helicopter or chainsaw. Engines employing a four-stroke cycle require that oil be delivered from a gravity-based sump. Consequently, four stroke engines typically are designed with the forces of gravity in mind. Two-stroke engines, therefore, offer simplicity and a significant power-to-weight ratio as compared to many four-stroke engine designs. 
   Disadvantages of the two-stroke air-standard cycle generally involve wear, fuel efficiency and pollution. The lack of a dedicated lubrication system typically results in a high rate of component wear. Further, two-stroke reciprocating engines, which employ a conventional crankshaft, also experience accelerated wear of the piston. To better understand this phenomena, it should be appreciated that the eccentricity of the crankshaft causes the piston rod to be oriented off-axis relative to the piston/cylinder axis. As such, a lateral component of the resultant force vector imposes high frictional forces between the piston and cylinder. Consequently, the piston rings wear, pressure is reduced i.e., causing blow-by, and fuel efficiency decreased. Other disadvantages are simply due to the way fuel is burned (or not burned) in two stroke engines. For example, the exhaust phase of the cycle is, at least in part, combined with the fuel intake and compression phase of the cycle. Consequently, exhaust gases are intermixed with a fresh charge of air-gas, hence, the mixture for ignition is non-optimum, i.e., contaminated by exhaust gases from the previous stroke. Similarly, inasmuch as the intake and exhaust occur nearly simultaneously, but along opposite sides of the cylinder, fresh fuel may be exhausted before ever being compressed and ignited. Consequently, two-stroke engines are not highly fuel efficient. 
   The principle advantage to a four stroke air-standard cycle (or Otto cycle) relates to fuel efficiency. More specifically, four stroke engines employ a stroke entirely dedicated to the exhaust of combusted gases, hence, four stroke engines burn cleaner and more efficiently that two stroke engines. That is, combusted gases do not intermix with a fresh charge of air-fuel in or during the compression/ignition stroke. Furthermore, four-stroke engines can have independent/dedicated oil and fuel reservoirs, i.e., do not use a gas-oil mixture, hence four stoke engines experience less wear and are less costly to operate. 
   The disadvantages of four stroke engines have been discussed above, i.e., when being compared to a two stroke engine, however, suffice it to say that four stroke engines deliver significantly less power output than two stroke engines. 
   Diesel two and four stroke cycles have the same advantages and disadvantages as those discussed above in connection with the Carnot and Otto air-standard cycles. Diesel engines do, however, allow high compression ratios inasmuch as the flash point (i.e., the temperature at which the fuel ignites) of Diesel fuel is substantially higher than conventional gasoline fuel. While this can offer the advantage of high power output, Diesel fuel contains less energy than gasoline (on a BTU/in 3  or volumetric basis) and does not produce the same power output when compared to gasoline bumming engines. Generally, the advantage of Diesel engines relates to the low cost of Diesel fuel and the relatively high efficiency with which it burns. 
   All of the above air-standard cycles and engine designs operate efficiently at relatively high rotational speeds. For example, a gas turbine engine is typically efficient at about ten-thousand (10,000) RPM. Four-stroke automobile engines are efficient within a range of about fifteen hundred to three thousand (1,500 to 3000) RPM. This is also true for the Wankel rotary engine. Typically, such rotational velocities are orders of magnitude above useful speeds to, for example, drive automobile tires, helicopter rotors, ship propellers etc. Consequently, all require speed reduction devices, e.g., transmissions, to lower and control the speed of output drive shafts. It will be appreciated that such devices add significant weight, require periodic maintenance, and are costly to fabricate, operate and maintain. 
   Other disadvantages of ICEs of the prior art relate to the weight distribution of conventional designs and to a lack of balanced torque output. With respect to the former, the center of gravity (C.G.) of prior art ICEs is frequently offset with respect to the output shaft axis. While this does not present difficulties in many applications, in other applications, such as a compound helicopter, it is beneficial to have the engine C.G coincident with the output drive shaft axis. For example, helicopters typically are designed such that the turbine engines are juxtaposed relative to the helicopter transmission. Despite the output orientation of the turbine engine (which faces forward), a rather elaborate bevel gearing system is employed to ensure that the center of gravity of the turbine engine lies in the same plane (normal to the longitudinal axis of the helicopter). As such, this drive-train configuration is non-optimal in terms of weight and is highly mechanically complex. 
   With respect to the latter, helicopters typically employ anti-torque devices to counter-act the torque developed in the fuselage as a result of the high torque required to drive the main rotor system. Conventional anti-torque devices employ tail rotors or propulsive thrusters to generate a force vector equal and opposite to the engine-generated moment vector, i.e., at a calculated distance from the rotational axis. As such these devices, which include tail cone structure, tail drive shafts, tail rotor gearboxes also add unnecessary weight. 
   A need, therefore, exists for an ICE which maximizes energy conversion, eliminates the need for intermediate speed reduction devices, e.g., speed reducing transmissions, improves performance, enhances reliability, reduces weight and minimizes mechanical complexity. 
   SUMMARY OF THE INVENTION 
   It is the object of the present invention to provide an Internal Combustion Engine (ICE) that provides high torque output at low rotational velocity thereby reducing or eliminating the need for intermediate speed reduction devices, e.g., transmissions. 
   It is yet another object of the present invention to provide such an ICE that minimizes mechanical complexity for improved reliability. 
   It is still yet another object of the present invention to provide an ICE which minimizes or eliminates the need for piston/cylinder lubricants or lubricant systems. 
   It is yet a further object of the present invention to provide an ICE which employs a reciprocating piston arrangement for maximizing power output. 
   It is another object of the present invention to provide a reciprocating piston ICE which minimizes transverse loading on the reciprocating piston thereby reducing wear and improving reliability. 
   It is another object of the present invention to provide such a reciprocating piston ICE that employs counter-rotating output shafts for maximizing power output while balancing torque output. 
   It is still yet another object of the present invention to provide a reciprocating piston which employs the advantageous features of a two-stroke air-standard cycle while maximizing scavenging pressure to improve performance. 
   It is yet still another object of the present invention to provide a two-stroke reciprocating piston that generates a power stroke with each stroke of the piston; 
   It is still another object of the present invention to provide a second output drive shaft that is timed relative to the first or primary output drive shaft for driving auxiliary equipment, 
   These and other objects of the invention are achieved by a an Internal Combustion Engine (ICE) having at least one output drive shaft driven by a pair of drive cams disposed within a housing. In a first embodiment of the invention, a plurality of reciprocating pistons are disposed about the periphery of the housing and a piston rod, having a central shaft and cross member perpendicular thereto, is disposed within radially oriented apertures of the housing. The housing defines at least two chambers and includes aligned apertures for accepting the output drive shaft and a radially oriented cylindrical bore for accepting each of the pistons. Drive cams are disposed in each of the housing chambers and are rotationally coupled to the output drive shaft. Each of the drive cams has a continuous pathway circumscribing the drive shaft axis and defines a plurality of lobes. Bearing means is interposed between and connects an outermost end portion of each of the cross members and the lobed pathway of the drive cams. In operation, axial motion of the piston rod acts on the lobes of the drive cams to effect rotational motion thereby imparting torque to the output drive shaft. 
   In a second embodiment of the invention, the Internal Combustion Engine (ICE) for delivers torque balanced power output. In this embodiment, the first and second drive cams are disposed within a chamber of the housing and are driven in opposite rotational directions in response to axial reciprocation of the piston/cylinders. More specifically, piston rods, which include a central shaft disposed within a radial aperture of the housing and a cross-member connecting to and disposed perpendicular to the central shaft, impart torque to the drive cams via engagement with lobed raceways thereof. The drive cams are angularly offset such that the axial motion of the piston rods imparts opposing torque vectors on the drive cams. As such, the first and second output drive cams, which are each connected to one of the first and second drive cams, are driven in opposite rotational directions thereby delivering torque-balanced output. 
   In yet a third embodiment of the invention, the number of lobes on one of the drive cams is a multiple of the number of lobes on the other of the drive cams. In this embodiment, the speed of the first output drive shaft is also a multiple of the speed of the second output drive shaft. Furthermore, the drive shafts may co-rotate or counter-rotate relative to each other. 
   In yet other embodiments of the invention, an auxiliary drive shaft or tertiary output drive shaft is driven by timed gear that intermeshes with teeth formed about the periphery of one or both of the drive cams. In this embodiment, the auxiliary drive shaft extends through the housing, between adjacent piston/cylinders and is timed relative to the speed of the first and second output drive shafts. 
   In another embodiment, a second ignition device is disposed through the piston cylinder, in the lower portion of the cylinder i.e., beneath the reciprocating piston, to provide a power stroke with each stroke of the piston. In this embodiment, fuel is injected and expelled through intake and exhaust ports disposed in the lower portion of the cylinder as a function of the position of the piston within the cylinder (functioning as a valve). As such the piston rod, which is sealed relative to the housing aperture, is subjected to tensile loads (during the upward power stroke) and compression loads (during the downward power stroke). 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete understanding of the present invention and the attendant features and advantages thereof may be had by reference to the following detailed description of the invention when considered in conjunction with the following drawings wherein: 
       FIGS. 1   a ,  1   b , and  1   c  depict schematic views of the Internal Combustion Engine (ICE) according to the present invention wherein  FIG. 1   a  the output drive shafts of the ICE are driven in the same rotational direction, in  FIG. 1   b  the output drive shafts of the ICE are co-axial and counter-rotate relative to each other, and, in  FIG. 1   c , output drive shafts of the ICE are driven in the same rotational directions but at different rotational speeds; 
       FIG. 2  depicts a front view of the ICE according to the present invention; 
       FIG. 3  depicts a side view of the ICE according to the present invention; 
       FIG. 4   a  depicts an exploded view of the ICE of the present invention including a housing, piston/cylinders disposed about the periphery of the housing, piston shafts, a pair of drive cams having lobed raceways, and output drive shafts; 
       FIG. 4   b  depicts an isolated front view of a drive cam according to the present invention; 
       FIG. 4   c  depicts a cross-sectional view taken along line  4   c — 4   c  of  FIG. 4   b;    
       FIG. 5  depicts a cross-sectional view taken substantially along line  5 - 5  of  FIG. 3 ; 
       FIG. 6  depicts a cross-sectional view taken substantially along line  6 — 6  of  FIG. 2 ; 
       FIG. 7  depicts an alternate embodiment of the invention wherein a second ignition device is disposed in the lower portion or chamber of the piston/cylinder to augment the power output of the piston/cylinder; 
       FIGS. 8   a ,  8   b , and  8   c , depict an alternate embodiment of the invention wherein the drive cams rotate in opposite directions and are shown in several operating positions in response to axial displacement of a piston rod; 
       FIG. 9  is a partially broken away, cross sectional view taken substantially along line  9 — 9  of  FIG. 2  depicting an alternate embodiment of the present invention wherein one or both of the drive cams include peripheral gear teeth which engage a bevel or pinion gear to establish and fix the relative angular alignment of the drive cams, to provide another output for driving auxiliary equipment, and/or for load sharing; 
       FIG. 10  depicts schematic view of another embodiment of the ICE wherein the drive cams and piston/cylinder have been modified to accommodate a four stroke air-standard cycle. 
   

   BEST MODE FOR CARRYING OUT THE INVENTION 
   The present invention relates to a new and useful cam driven Internal Combustion Engine (ICE) that delivers high torque at low rotational velocity. The preferred embodiment is described in the context of eight reciprocating pistons acting on two internal rotating drive cams that, in turn, drive coaxial output shafts. It will be appreciated, however, that the inventive features of the invention may be applied to similar internal combustion engines having fewer or a greater number of reciprocating pistons, to those having more than two cam drives, to those wherein the drive cams rotate in the same or opposite rotational directions, or to those having a single output drive shaft. 
   Before discussing the internal details and specific embodiments of the invention, it is useful to obtain a broad overview of the invention by referring to the schematics shown in  FIGS. 1   a ,  1   b ,  1   c . In the broadest sense of the invention, the ICE comprises a housing  12  which supports: a reciprocating piston means  14 , i.e., piston/cylinders, first and second drive cams  70   a ,  70   b , and first and second output drive shafts  20   a ,  20   b . The piston means  14  drives a plurality of piston rods  30  radially and linearly within the housing  12 . The first and second drive cams  70   a ,  70   b  are driven rotationally in response to the linear motion of the piston rods  30 . 
   In  FIGS. 1   b  and  1   c , the first and second drive cams  70   a ,  70   b , include a plurality of lobes  76  which are either in-phase (as seen in  FIG. 1   b ) or, out-of-phase (as seen in  FIG. 1   c ). The first and second drive cams  70   a ,  70   b  are responsive to the axial motion of the piston rods  30 , i.e., acting on the lobes, such that each is rotationally driven. In  FIG. 1   b , the in-phase lobes cause the drive cams to be driven in the same rotational direction, while in  FIG. 1   c , the out-of-phase lobes  76  cause the drive cams  70   a ,  70   b  to be driven in opposite rotational direction. As such, the output drive shafts  20   a ,  20   b , which are rotationally coupled to the drive cams  70   a ,  70   b , may drive in the same or opposite rotational direction. When the drive shafts  20   a ,  20   b , drive in opposite rotational directions, a torque-balanced output is achieved. 
   The following drawings illustrate an exemplary embodiment of an Internal Combustion Engine (ICE) according to the present invention. More specifically, and referring to  FIGS. 2 and 3 , the ICE  10  according to the present invention includes a central housing  12  having a plurality of radially oriented reciprocating piston/cylinders  14  disposed about the periphery of the housing  12 . While the piston/cylinders  14  are depicted as being separate elements mounted to the central housing  12 , one will appreciate that the outer housings  16  of each piston/cylinder may be integral with the central housing  12 , i.e., the bore of each piston (not shown in  FIGS. 2 and 3 ) may be machined integrally therein. Consequently, the housing  12  generically refers to any structure which functions to support internal working components, therefore, includes and items such as the outer cylinder housing  16 . 
   Each of the piston/cylinders  14  includes an ignition device, e.g., a spark plug  18 , and employs a Carnot two-stroke air-standard combustion cycle, hence, the intake and exhaust ports,  19   i   u ,  19   e   u , respectively, are located at an appropriate position relative to the internal reciprocating piston (not shown}. In the preferred embodiment, the ICE  10  drives output drive shafts  20   a ,  20   b  and, may also drive one or more auxiliary output shafts  22  orthogonal to the axes  20   RA  of the output drive shafts  20   a ,  20   b . The output drive shafts  20   a ,  20   b , may be co-axial, concentric and disposed through a single side of the housing  12  as shown or may be co-axial, but extend outwardly from oppositely disposed sides of the housing  12 . That is, each of the output shafts  20   a ,  20   b , being 180 degrees from the other of the shafts  20   a ,  20   b .  FIG. 3  shows the second output shaft  20   b  in dashed lines to illustrate this embodiment of the invention. 
   In  FIG. 4   a , an exploded view of the ICE  10  is shown to reveal the principal internal components. Certain well-known elements such as gaskets, seals, shaft bearings etc., have been omitted to enhance the clarity of illustration. As briefly discussed in the schematic drawing, the principle internal components of the ICE  10  include, the reciprocating pistons  24 , piston rods  30 , a central body portion  40  of the housing  12 , and drive cams  70   a ,  70   b . The structure, function and interaction of each are described below. 
   Each piston  24  reciprocates within a central bore  26  of the piston/cylinder housings  16  and drives a piston rod  30  having a generally inverted-T configuration. That is, each piston rod  30  comprises a central shaft  32  and a cross member  34  which is substantially perpendicular to the central shaft  32 . The central shaft  32  is rigidly or articulately mounted to the underside of the piston  24  and is substantially radial relative to the axes  20   RA  of the output drive shafts  20   a ,  20   b . The benefits of such orientation will be described in greater detail below, however, the orientation of the piston rod  30  will generally impact the torque output of the ICE  10 . Disposed over the cross member  34  is an innermost or first rolling element bearing  36  and an outermost or second rolling element bearing  38 , the function of each being described in greater detail hereinafter. 
   The central housing  12  includes a center body portion  40  having a generally octagonal-shaped peripheral rim  42  and a central web  44  formed internally of and integrally with the peripheral rim  42 . End plates  46   a ,  46   b , having the same octagonal shape of the peripheral rim  42 , close each end of the center body portion  40  to define internal chambers or cavities between the central web  44  and each end plate  46   a  and  46   b . Moreover, a central aperture  120  is formed in at least one of the end plates  46   a ,  46   b  to accept the output drive shafts  20   a ,  20   b.    
   The end plates  46   a ,  46   b  of the central housing  12  may be affixed to the center body portion  40  by any of a variety of means. In the preferred embodiment, the end plates  46   a ,  46   b  are fastened by a plurality of through-bolts (not shown) to the peripheral rim  42  of the center body portion  40 . 
   While the central housing  12  is shown to have a generally octagonal external appearance, such configuration facilitates the mounting of each piston/cylinder housing  16  to the central housing  12 , i.e., along planar surfaces  48  thereof. As mentioned previously, each piston/cylinder  14  may be integrally formed or machined within the central housing  12  or may vary in number, and, consequently, the external configuration thereof may take on a variety of shapes including cylindrical, hexagonal, decagonal, or other polygonal configurations. 
   The center body portion  40  further includes radially oriented apertures  50  and slots  60  for accepting each piston rod  30 . More specifically, the apertures  50  extend through the peripheral rim  42  and central web  44  in a substantially radial direction, i.e., toward the drive shaft axes  20   RA , and accept the central shaft  32  of each piston rod  30 . The slots  60  extend through the web  44  in a lateral direction and accept the cross members  34  of each piston rod  30 . Moreover, the innermost bearings  36  are interposed between the cross members  34  and each slot  60 . Finally, in the preferred embodiment, the central web  44  includes an output aperture  64  aligned with a central aperture  12   o  of the housing for accepting at least one of the output drive shafts  20   a .  20   b.    
   Within the central housing  12  are first and second drive cams  70   a ,  70   b  each having a generally disc-shaped configuration and an axis of rotation  70   RA . More specifically, and referring to  FIGS. 4   a – 4   c , each of the drive cams  70   a ,  70   b  includes a continuous raceway or cam path  72  circumscribing its rotational axis  70   RA  and having a repeating sinusoidal pattern or configuration (only one drive cam  70   a  is depicted in  FIGS. 4   b ,  4   c  inasmuch as, in this embodiment of the invention, the drive cams  70   a ,  70   b  are essentially identical). In the preferred description, each raceway  72  defines approximately four (4) sign waves or four (4) “lobes”  76  (see  FIG. 4   b ). Each lobe  76 , furthermore, defines power and compression stroke surfaces  76 PS and  76 CS, respectively. While the preferred embodiment depicts a sign wave configuration to define the lobes  76 , the invention anticipates other variations of a wave pattern and is not limited to this specific shape or curvilinear raceway. 
   Furthermore, the drive cams  70   a ,  70   b  are paired such that the raceway  72   a  of a first drive cam  70   a  faces the raceway  72   b  of a second drive cam  70   b . In a first embodiment of the invention each of the raceways  72  are symmetric, i.e., the lobes  76  are in-phase (i.e., angularly aligned), and the drive cams  70   a ,  70   b , co-rotate about rotational axis  70   RA . In a second embodiment, discussed in greater detail below, the raceways  72   a ,  72   b  are out-of-phase (i.e., the lobes  76  are not angularly aligned), and the drive cams  70   a ,  70   b  counter-rotate relative to each other. In yet another embodiment, the number of lobes may vary, (i.e., multiples of each other) and the drive cams may operate at different rotational speeds, either in the same or opposite directions. 
   Referring again to  FIG. 4   a , each of the drive cams  70   a ,  70   b  are rotationally coupled to and drive one of the output drive shafts  20   a ,  20   b . In the preferred embodiment, the drive cams  70   a ,  70   b  are press-fit to the output drive shafts  20   a ,  20   b , however, other connecting means such as splines, teeth, or keyways may be employed. The drive shafts  20   a ,  20   b  may be coupled to drive in the same rotational direction or co-axial (one shaft  20   b  within the other shaft  20   a ) to drive in opposite rotational directions. 
   A better understanding of the operation of the inventive ICE  10  may be had by examination of  FIGS. 5 and 6 . Referring to  FIG. 5 , the pistons  24  of each piston/cylinder  14  reciprocate axially to effect linear motion of the respective piston rods  30 . In the preferred embodiment, a Carnot two-stroke air-standard cycle is employed to produce maximum power (for each piston stoke) and to eliminate the need for complex valving. The axes  32   A  of each central shaft  32  is oriented in a substantial radial direction relative to the rotational axes  20   RA  of the output drive shafts  20   a ,  20   b . While a radial orientation is preferred, it may be desirable to offset the axes  32   A  to produce a larger moment couple thereby producing even greater torque output. 
   Inasmuch as the motion of piston rod shaft  32  is linear, it is desirable to seal the central shaft  32  relative to its respective piston aperture  50 , e.g., via a conventional O-ring seal  50   OR  (seen only in  FIG. 6 ). As such, the scavenging pressure in the lower portion or chamber of the piston cylinder  24   u  may be substantially increased to boost the pressure within the piston/cylinder  14 , i.e., as the air-gas mixture is injected into the piston/cylinder  14 . In an alternate embodiment of the invention, discussed in greater detail hereinafter, a secondary ignition device may be introduced on the underside  24   u  of the piston  24 , thereby generating a power stroke with each stroke of the reciprocating piston  24 . 
   The cross member  34  of each piston rod  30  engages the radial slot  60  of the central web  44  and each of the drive cams  70   a ,  70   b  (see  FIG. 6 ). Specifically, the innermost bearings  36  ride along and engage the radial slot  60  and the outermost bearings  38  engage and ride within the raceways  72   a ,  72   b  of the first and second drive cams  70   a ,  70   b . In operation, the axial displacement of the piston rod  30  causes the cross members  34  to act on the inclined power and compression surfaces  76 PS,  76 CS (shown in phantom lines in  FIG. 5 ) of the lobed raceways  72   a ,  72   b , to effect rotational motion of the drive cams  70   a ,  70   b . More specifically, a downward stroke of the piston rod  30  on the power stroke surface  76 PS of the lobe  76  generates a tangential load on the drive cams  70   a ,  70   b , thereby driving the cams, and consequently, the output drive shafts  20   a ,  20   b . The inertia of the drive cams  70   a ,  70   b , in conjunction with the inertia of the output drive shafts  20   a ,  20   b , causes the compression stroke surfaces  76 CS to drive the piston rod  30  upward, thereby compressing the air-fuel mixture within the piston cylinders  14 . 
   As a consequence of the linear-to-rotary translation, it will be appreciated that high torque loads are developed in the cross members  34 . The ICE  10  of the present invention employs an efficient torque reaction means defined by the interaction between the radial slots  60  in the central web  44  and the innermost rolling element bearings  36 . More specifically, the radial slots  60  are particularly rigid, i.e., structurally efficient, within the housing  12  due to the structural continuity of the central web  44 , i.e., the central web  44  is a unity structure extending diametrically across the center body portion  40 , i.e., the peripheral rim  44 , of the housing  12 . As such, in this embodiment of the invention, the central web  44  defines two discrete housing chambers  12   C1  and  12   C2  (see  FIG. 6 ) Moreover, the ICE  10  employs rolling element bearings, in contrast to various sliding element bearings occasionally seen in the prior art, to react the load along a “point”, and between each drive cam  70   a  or  70   b  and the piston rod shaft  32 . The combination of the location, i.e., the torque reaction means, and the proximate positioning to the drive cams  70   a  or  70   b , i.e., the source of the torque to be reacted, reduces the moment arm therebetween and, consequently, minimizes the torque load to be reacted. 
   Referring again to  FIG. 4   b , the drive cams  70   a ,  70   b  rotate though an angle equal to the arc length of one lobe  76  with each cycle of a reciprocating piston. In the described embodiment, a drive cam having four lobes will rotate through an angle θ of about 90 degrees with every piston cycle (i.e., two strokes). It will, therefore, be appreciated that the ICE  10  of the present invention avails the designer nearly limitless options with respect to determining an engine speed (i.e., of the output drive shafts) by defining the number of lobes to be employed. For example, since two cycle reciprocating piston/cylinders operate very efficiently at about 1500 to 2000 cycles (or 3000 to 4000 strokes) per minute, drive cams  70   a ,  70   b  having four lobes will rotate at about 400 to 500 revolutions per minute. Alternately, drive cams having 10 lobes will rotate at about 150 to 200 revolutions per minute. 
   In the preferred embodiment, the firing pattern of the piston/cylinders comprises the ignition and downward stoke of four (4) pistons simultaneously, each acting on a power stroke surface  76 PS of one lobe  76 . In an ICE having eight piston/cylinders, alternating pistons/cylinders are fired first, and the remaining piston/cylinders are subsequently fired. Consequently, with each 45 degrees of drive cam rotation, a power stoke is initiated. When employing an odd number of lobes and an even number of P/Cs, the firing pattern may be even smoother. That is, a firing pattern may be based upon a calculation which divides a full rotation (i.e., 360 degrees) by the quotient of the number of P/Cs with the number of drive cam lobes. For example, an ICE  10  having eight (8) P/Cs and three (3) drive cam lobes yields a quotient of twenty-four (24). A full rotation of 360 degrees divided by 24 suggests that an ICE so configured can employ a firing pattern having a power stroke with every 15 degrees of drive cam rotation. Thus, a smoother, i.e., low vibration ICE may result. 
   As previously mentioned, the linear motion of the piston rods  30  provides an opportunity to seal the central shaft portions  32  thereof to the respective  50  thereby increasing the scavenging pressure in a conventional two-stroke piston cylinder. Furthermore, in yet another embodiment of the invention shown in  FIG. 7 , a second ignition device  90  may be employed in each cylinder  14  and on opposing sides of the piston  24  to develop a power stroke with each stroke of the piston  24 . In this embodiment, fuel is injected and expelled through intake and exhaust ports  19   i   L ,  19   e   L , respectively, disposed in the lower portion of the cylinder as a function of the position of the piston  24  within the cylinder  14  (functioning as a valve). Furthermore, the cross member  34  of each piston rod  30  acts on opposing first and second power stroke surfaces  76 PS- 1   76 PS- 2 , such that the central shaft  32  of the piston rod  30  is in compression upon a downward stroke of the piston  24  and in tension (acting on the uppermost raceway surface  76 PS- 2 ) upon an upward stroke of the piston  24 . 
   The simplified construction and configuration of the ICE  10  of the present invention facilitates fabrication via a variety of low-cost manufacturing approaches. Reference is made collectively to  FIGS. 4   a  through  7 . Preferably, the center body portion  40  of the housing  12 , and the drive cams  70  are high-speed machined using Numerically Controlled (NC) cutting apparatus. For example, a block of steel or aluminum in the general shape of the center body, e.g., a solid cylinder, octagon, etc. formed by forging, machining, casting or other known method. Initially this block is about six (6″) inches in thickness. Piston rod apertures  50  are then drilled radially inwardly from the periphery of the cylindrical block. The longitudinal depth of the apertures  50  include the combined length of the central shaft  32  of the piston rod  30  (from the plane defined by the underside of the piston to the tip end including the thickness of the cross member  34 ) and the length of the slot  60  (e.g., minimally the length of piston stroke). Further, if timing gears are desired, one or more additional apertures are also drilled. 
   Next, the block is laid flat to high speed machine each side of the central web  44 . In this step, material is cut away to a depth of about two inches thereby creating each cam chamber or cavity  12   c1 .  12   c2  and leaving a web thickness of about two (2″) inches. Minimally, the thickness of the central web  44  will be about one and one-half to two times (1½–2×) the diameter of the central shaft  32  of the piston rod  30 . Again, if a timing gear  80  is anticipated, a cut-out is machined in the web  44  to accept the gear  80 . The radial slots  60  are then machined through the central web  44  intersecting with each piston rod aperture  50 . The width of the slot  60  will be larger than the diameter of the piston rod apertures  50  and slightly greater than the diameter of the innermost needle or roller bearing  36 . In the preferred embodiment, the diameter of the bearing  36  is about one and three-eights inches (1⅜″) and the width of the radial slot  60  is about one and seven-sixteenths inches (1 7/16″). As alluded to above, the slot length will be minimally equal to the stroke of the piston rod  30 , which in the preferred embodiment is about two inches (2″). A central aperture  64  is also drilled to accept the coaxial output drive shafts  20   a ,  20   b . Next, the external surfaces of the peripheral rim  42  is ground to accept each piston/cylinder housing  16  and end plates  24   a .  24   b.    
   Upon completion of the initial rough-machining operations, the bearing surfaces  60   s  of the slots  60  and the piston rod aperture surfaces  50   s  may be hardened to provide greater wear resistance. Accordingly, the bearing surfaces  50   s ,  60   s  may be masked and the entire center body  40  placed in a copper bath to electolytically deposit copper on all exposed surfaces. Next, the masking material is removed from the bearing surfaces  50   s ,  60   s  and the center body  40  is treated in a carborization vessel. Therein, carbon penetrates and permeates all bearing surfaces without penetrating areas which are copper-coated. Finally, the bearing surfaces  50   s ,  60   s  and the peripheral rim  42  are precision ground to final dimensions. 
   The drive cams  70   a ,  70   b  are fabricated in a similar manner. Plates having a cylindrical or disc-like configuration are routed to form the lobed cam raceways  72 . Each of the drive cams  70   a ,  70   b  are approximately one and one-half inches (1½″) in thickness. Furthermore, the height of the cam raceways  72  are slightly greater than the diameter of the outermost needle or ball bearing  38  approximately or about one and seven-sixteenths inches (1 7/16″), and the depth of the cam raceways  72  are about one and one-quarter inches (⅝″). Similar to the center body housing, it may be desirable to surface harden the cam raceways  72 . The same masking and carborizing steps may be followed as described above. 
   The present invention is useful in any engine application wherein high torque is required in combination with low rotational speed. For example, tug boat engines must generate enormously high torque while turning a thrusting propeller at very low RPM. Similarly, rotorcraft turbine engines must generate high torque while turning the lifting rotor at about 300 revolutions per minute. The ICE  10  of the present invention is applicable to both such applications, and many more, while at the same time, eliminating the cost, maintenance and weight of intermediate speed reduction devices. That is, by first determining/designing the number of drive cam lobes  76 , the ICE  10  of the present invention may be configured to produce a rotational speed that is appropriate for the high torque, low speed application. 
   Should slight speed deviations be sought or desired, the speed of the reciprocating pistons  24  may be increased or decreased to vary the speed of the drive cams  70   a ,  70   b , and output drive shafts  20   a ,  20   b . For example, it is common for a helicopter rotor to be controllable within a range of between within 93% NR to about 107% NR. The ICE of the present invention could be readily adaptable to this application thereby eliminating the need for input modules, main gearbox modules, and multi-stage, speed-reducing epicyclical gearing. As such, hundreds of pounds of intermediate gearing/transmissions could be eliminated. 
   Thus far, the ICE of the present invention has made little or no distinction between drive cams  70   a ,  70   b  which are “in phase”, i.e., angularly aligned relative to one another, or to those which are “out-of-phase”, i.e., angularly offset. In general, all of the above teaching can be employed for either drive cam orientation or rotational direction. Referring now to  FIGS. 8   a ,  8   b  and  8   c , an important and particularly useful embodiment of the ICE is depicted wherein the drive cams  70   a ,  70   b  are out-of-phase with respect to one another (drive cam  70   a  is shown in solid lines while drive cam  70   b  is shown in dashed lines). That is, the lobes  76  of the first drive cam  70   a , are angularly advanced with respect to second drive cam  70   b . Referring to  FIG. 8   a , the cross member  34  of each piston rod  30  engages the lobes  76  is a “scissors-like” pattern, wherein during a downward power stroke, the cross member  34  splits the lobes, as if pushing down the cutting edges of a scissors (causing the scissors to open).  FIG. 8   b  shows a second angular position wherein the drive cams are rotating in opposite rotational directions as indicated by arrows F T . Yet a third angular position is shown in  FIG. 8   c , wherein the drive cams  70   a .  70   b  and respective lobes  76  essentially overlap, yet are ninety (90) degrees out-of-phase. 
   During an upward compression stroke the lobes  76  come together, i.e., pushing the cross member upward, like the cutting blades of a scissors. One can simply envision the reverse of the positions depicted in  FIGS. 8   a – 8   c . That is, examining  FIGS. 8   a – 8   c  in reverse order, or from  FIG. 8   c , to  FIG. 8   b  and finally to  FIG. 8   a . Consequently, when positioning the lobes in an out-of-phase orientation, the drive cams  70   a ,  70   b  counter-rotate at the same rotational speed, i.e., assuming that each drive cam  70   a  or  70   b  contains the same number of lobes  76 . Furthermore, the output drive shafts  20   a ,  20   b , counter-rotate to torque-balance the power output. 
   In yet another embodiment (not illustrated), the number of lobes  76  on one of the drive cams  70   a ,  70   b , is a multiple number or integer relative to the number of lobes  76  on the other of the drive cams  70   a ,  70   b . For example, if the number of lobes  76  of the first drive cam  70   a  is two (2) then the number of lobes on the second drive cam  70   b , is a multiple of two (2), hence is four (4), eight (8), etc. As such, the second drive cam  70   b  rotates at one-half the rotational speed as the first drive cam  70   a . Moreover, this variation in lobe number applies to both earlier embodiments wherein the drive cam lobes  70   a ,  70   b  rotate in the same or opposite directions. This embodiment is useful wherein different output speeds are desired. 
   In  FIG. 9 , an alternate embodiment of the present invention is shown wherein each of the drive cams  70   a ,  70   b  include peripheral gear teeth  78  which jointly engage a timing gear  80  to establish and fix the relative angular alignment of the drive cams  70   a ,  70   b . That is, the housing  12  may be adapted to include a means for rotationally supporting the timing gear  80  along the underside of the peripheral rim  42 . The timing gear includes bevel or spur gear teeth  82  for intermeshing with bevel or face gear teeth  78  of each drive cam  70   a ,  70   b . In the preferred embodiment, an opening  44   o  is formed in the central web  44  adjacent the underside of the peripheral rim  42  and a radial aperture  44 A is formed in the rim  42  to accept a radial shaft  84 . The radial shaft  84  extends into the opening  44   o  and functions to rotationally support the timing gear  80  which rotates about the shaft  84 . As such, the timing gear  80  functions to ensure that the drive cams  70   a ,  70   b  maintain their desired angular offset or rotational orientation, while furthermore, serving to effect load sharing between the cams  70   a ,  70   b . That is, whenever a singular input (such as, in the present invention, a piston rod  30 ), effects the transfer of load into two rotating output devices (such as the drive cams  70   a ,  70   b  of the present invention), load sharing must be considered to ensure that all of the load is not transferred to only one output device. Consequently, the timing gear  80  also functions as a means for effecting load sharing by causing an overload condition in one of the rotating drive cams  70   a ,  70   b  to be transferred to the other of the drive cams  70   a ,  70   b.    
   Furthermore, the radial shaft  84  may extend through the peripheral rim  42  to function as a timed shaft for driving auxiliary equipment. That is, the radial shaft  84  may dually serve as the auxiliary drive shaft  22  for driving such equipment as alternators, generators, oil pumps, oil coolers, etc. For instances wherein synchronous timing or load sharing are not desired, the timing gear  80  may function solely to drive an auxiliary output drive shaft. Furthermore, while the timing gear  80  is shown as dually functioning to synchronize and provide an auxiliary drive, the timing gear  80  need not engage both drive cams  70   a ,  70   b , nor is the use thereof limited to applications having counter-rotating drive cams  70   a ,  70   b.    
   For example, the timing gear  80  may be driven by only one of the drive cams having peripheral gear teeth (this and subsequent configurations are not shown). Furthermore, the timing gear may be disposed to either side of one or both drive cams  70   a ,  70   b . Finally, one or more timing gears may be employed and may intermesh with adjacent gears of the same or varying diameter dimensions to increase or decrease the rotational speed of the auxiliary shafts. 
   The counter-rotating, co-axial output shaft configuration of the present invention is particularly useful in applications wherein torque is sufficiently high so as to unintentionally or adversely affect the body or structure to which the ICE is affixed to or attached. To demonstrate this need, one could envision a drag racing automobile wherein the engine torque is sufficiently high to lift the front wheels of the automobile. Consequently, automobile designers resort to lengthening the nose or front end of the vehicle to develop a downward, gravity-induced, torque moment. Other, more common examples include the conventional compound helicopter or rotorcraft. In helicopter applications, torque loads are sufficiently high on the aircraft fuselage to require that other devices be employed to counteract the torque of the main rotor shaft. Typically, a tail rotor is employed to provide a yaw component of thrust to counteract the torque developed at the main bull gear where torque is input to the main rotor shaft. It will be appreciated, therefore, that the torque balanced-output of an ICE  10  according to the present invention could eliminate the need for a tail rotor, and the hundreds of pounds of weight associated with the tail drive shafts, tail rotor gearbox, and tail cone. 
   Yet other examples include heavy farm equipment wherein elongate arms or other stabilizing structure are occasionally used to “steady” the vehicle. Here again, high torque is developed in the engine, which causes the entire vehicle to rotate. Use of the ICE  10  of the present invention could eliminate the need for such stabilizing structure by providing torque-balanced output. 
   Should four-stroke fuel efficiency be desired, the ICE of the present invention may be readily adapted to accommodate this air-standard cycle.  FIG. 10  shows a schematic of an exemplary embodiment of the ICE  10  adapted for a four-stroke cycle. Therein, the ICE  10  includes valve means  100  responsive and timed relative to the rotational displacement of the drive cams  70   a ,  70   b . More specifically, the valve means includes spring-loaded plungers  102 , rocker arms  104  and conventional stem valves  106 . Each spring-loaded plunger  102  is disposed within a bore  108  of the housing  12  and contacts peripheral cam surfaces  110  formed about the periphery of one or both drive cams  70   a ,  70   b . In the preferred description, a first spring bias means is employed to maintain the plungers in contact with the peripheral cam surfaces  110  as the cams  70   a ,  70   b  rotate. 
   The intake and exhaust stem valves  106  are conventional and include a seat portion  112  and a stem portion  114 . The seat portion  112  is disposed internally of the cylinder and in register with a respective port  19   i  or  19   e , while the stem portion  114  connects to the seat portion  112  and extends through its respective port  19   i  or  19   e . The valves  106  are, furthermore, reposition able from an open position to a closed position, wherein the seat portion  112  thereof seats against the periphery of a respective port  19   i  or  19   e  in a closed position to provide a seal for preventing the flow of gases therethrough and permitting the flow of gases when in an open position. In the preferred description, a second spring bias means is employed to bias the valves  106  in an open or closed position while, furthermore, acting to support and center the valves  106  relative to its respective port. 
   The rocker arms  104  are disposed between and connect each spring-loaded plunger  102  to a respective each of the valves  106 . More specifically, the rocker arms  104  each have an input and output end  1161  and  1160 , respectively, and mount to the housing  12  about a pivot point  118 . Furthermore, each input end  1161  pivotally mounts to one of the plungers  102  and each output end  1160  pivotally mounts to one of the valves  106 . 
   In operation, rotation of the drive cams  70   a ,  70   b  within the housing  12  causes the peripheral cam surfaces  110  to displace the plungers  102 , thereby pivoting the rocker arms  104  and opening and closing the valves  106  as a function of the angular position of the drive cams  70   a ,  70   b.    
   Embodiments wherein the drive cams  70   a ,  70   b  rotate in opposite directions will require that each of the drive cams  70   a ,  70   b  include such cam surfaces. While the cam surfaces  110  are shown to project radially outward, it will be appreciated that any change in radial dimension, inwardly or outwardly will serve the intended purpose of the peripheral cam surfaces  110  (described in greater detail in the subsequent paragraphs). In the described embodiment there are at least two (2) such peripheral cam surfaces  110  equiangularly-spaced about the circumference of the drive cam  70   a  thereby opening and closing the valves  106  in a four stroke air-standard cycle. 
   In summary, the ICE  10  of the present invention provides a variety of advantages over prior art reciprocating piston engines which employ crankshafts and advantages over prior art turbine ICEs. Firstly, the ICE of the present invention capable of delivering superbly high torque while maintaining a relatively low output speed. As previously mentioned, tug boats, helicopters and locomotives are prime applications for the ICE of the present invention. Inasmuch as the ICE delivers this combination of attributes, the need for intermediate gear/speed reducing devices is eliminated or significantly diminished and, so too, are the weight, complexity, cost, and maintenance of such devices. Moreover, the rotational speed of the output drive shafts may be readily changed simply by altering the number of drive cam lobes  76 . 
   Furthermore, as will be especially appreciated from the exploded view of the invention illustrated in  FIG. 4 , the ICE of the present invention employs a minimum number of moving components, thereby minimizing and improving reliability. Inasmuch as the ICE of the present invention defines discrete housing chambers, i.e., the piston cylinder may be sealed relative to the drive cam chamber(s), lubricants may be isolated from fuel and exhaust gases. Consequently, oil is not contaminated, reducing the need for frequent oil changes. Moreover, the ICE of the present invention is structurally efficient. Torque loads are reacted via a central web  44  such that bending moments are not applied to the central shaft  32  of the piston rod  30  nor to the reciprocating piston  24 . As such, the reciprocating piston  24  does not experience sidewall scuffing or friction as is typically seen in ICEs employing crankshafts. In addition to prolonging the life of the piston rods, the ICE of the present invention eliminates or significantly reduces the need for oil in the fuel mixture (typically required in two-stroke reciprocating engines). 
   Inasmuch as the ICE preferably employs a two-stroke air standard cycle, the reciprocating piston delivers a power stroke with every two strokes of the piston. Furthermore, when employing a secondary ignition device  90  along the underside of the piston, a power stoke may be delivered with each stroke of the piston. Consequently, the ICE of the present invention maximizes power output. 
   Finally, the ICE of the present invention provides a torque-balanced output through the use of counter-rotating drive cams. As such, the body to which the ICE is affixed is not subjected to high torque loads, thereby eliminating the need for counter-balancing devices or fixtures, e.g., a helicopter tail rotor, or structural augmentation of engine mounts. Furthermore, the ICE provides a simple, accessible means for driving auxiliary power or take-off devices. That is, the timing gear, disposed between the drive cams and its thru-shaft, provide timed power output which may be used to drive alternators, generators, accumulators, tail rotor drive shafts, etc. 
   Although the invention has been described in terms of its various embodiments, one will appreciate that the teachings of the invention provide for various other embodiments which fall within the spirit and scope of the invention.