WO2017120141A1

WO2017120141A1 - Engine

Info

Publication number: WO2017120141A1
Application number: PCT/US2017/012043
Authority: WO
Inventors: Steven Charles Manthey; Micheal Steven MANTHEY
Original assignee: Advanced Engine Dynamics Corporation
Priority date: 2016-01-04
Filing date: 2017-01-03
Publication date: 2017-07-13

Abstract

This disclosure relates to an engine, and in one example embodiment, to a two-stroke opposed-piston internal combustion engines with ported cylinders. In certain embodiments, the engine is a barrel type engine with opposed pistons.

Description

ENGINE

BACKGROUND

Field

[0001] This disclosure relates to a two-stroke opposed-piston internal combustion engines with ported cylinders.

Description of the Related Art

[0002] An opposed-piston engine (OPE) is a reciprocating internal combustion engine characterized by use of pairs of pistons operating with opposed motions in a common cylinder without need of a cylinder head.

SUMMARY

[0004] An aspect of the present disclosure is the recognition that an opposed piston engine can have potential advantages including, high specific output, high specific torque, very high power density and increased thermal efficiency (arising in part from reduced heat soaking surface area as compared to conventional engines due to the elimination of the need for cylinder heads).

[0005] Potential advantages of certain embodiments of the disclosure described herein can include a low part-count given that the engine pistons can cyclically expose or occlude the exhaust and intake ports thereby eliminating the need for a valve train, camshaft pushrods, valve springs or valve keepers.

[0006] An aspect of the present disclosure can include a reciprocating internal combustion engine characterized by use of pairs of pistons operating with opposed motions in a common cylinder without need of a cylinder head. The engine includes a plurality of cylinders that are positioned around an output shaft. The plurality of cylinders are stationary and the output shaft rotates. The engine includes a pair of rotating cams.

[0007] An aspect of the present disclosure herein can include a reciprocating internal combustion engine of the type in which a plurality of cylinders are arranged in equally spaced relationship around a central axis, the pistons being parallel to one another and the said axis. [0008] An aspect of the present disclosure can include a "Barrel Engine" configuration of the type in which the drive mechanism involves rotating cams to create rotation of a central power shaft from the reciprocating motion of the pistons. An advantage of such an embodiment of type of engine is that a cam-actuated design can provide a programmable surface to tailor piston motion for each piston-stroke and realize a smoothness in piston motion in contrast to the extreme motion seen in conventional crank throw motion - thereby providing an opportunity for achieving improved thermal efficiency by increasing compression ratios beyond what the operational stresses associated with crankshaft-driven engines will generally permit.

[0009] Another aspect of the present disclosure is to provide such an engine which will be light in weight, small in size and consist of a minimum number of parts particularly in respect of the wearing parts.

[0010] Yet another object of certain embodiments of the disclosure is to provide such an engine capable of realizing high thermal efficiency by operating with very high compression ratios not generally considered viable with crankshaft - driven engines due to the prohibitively high operational and thermal stresses that such ratios would produce in conventional engines.

[0011] Yet another object of certain embodiments of the disclosure is to provide such an engine that can be easily coupled in a series of engines so as to aggregate the specific output of each engine and reduce the need in manufacture to produce engines of multiply sizes and displacements. Other objects and advantages of the disclosure will be hereinafter apparent in light of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Various embodiments are depicted in the accompanying drawings for illustrative purposes, and should in no way be interpreted as limiting the scope of the embodiments. Various features of different disclosed embodiments can be combined to form additional embodiments, which are part of this disclosure. [0013] Figures 1-13 are various views of an engine and its components according to an illustrated embodiment. In these Figures individual components are numbered in accordance with the number allocated to each component throughout this description.

[0014] Figure 1 is cross-sectional side view of the piston assemblies and cylinders of Figure 2 according to an illustrated embodiment of the present disclosure.

[0015] Figure 2 is a side perspective view of the engine of Figure 3 with an outer engine housing removed to illustrate the piston assemblies and cylinders according to an embodiment of the present disclosure.

[0016] Figure 3 is a side perspective view of the engine according to an illustrated embodiment.

[0017] Figure 4 is a front view of the inner and outer intake piston assemblies of the engine of Figure 3 according to an embodiment of the present disclosure.

[0018] Figure 5 is a side perspective view of the inner intake piston assembly and inner exhaust piston assembly of the engine of Figure 3 according to an embodiment of the present disclosure.

[0019] Figure 6 is a side perspective view of the outer intake piston assembly and outer exhaust piston assembly of the engine of Figure 3 according to an embodiment of the present disclosure.

[0020] Figure 7 is a side view of the output shaft, intake cam and exhaust cam of the engine of Figure 3 according to an embodiment of the present disclosure.

[0021] Figure 8 is a side perspective view of the output shaft of Figure 7.

[0022] Figure 9 is a rear perspective view of the engine of Figure 3.

[0023] Figure 10 is a front perspective view of the engine housing with the pistons removed.

[0024] Figure 1 1 is a top perspective view of the inner and outer intake assemblies and their associated pistons according to an embodiment of the present disclosure.

[0025] Figure 12 illustrates the rockers and rocker posts shown in Figure 1 1 with the inner and outer intake assemblies and their associated pistons removed.

[0026] Figure 13 is a front view of an intake manifold of the engine of Figure 3 according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE CERTAIN EMBODIMENTS

[0027] Various embodiments of an engine and methods of operating an engine are described below to illustrate various examples that may achieve one or more desired improvements. These examples are only illustrative and not intended in any way to restrict the general disclosure presented and the various aspects and features of this disclosure. The general principles described herein may be applied to embodiments, combinations, subcombinations and applications other than those discussed herein without departing from the spirit and scope of the disclosure. Indeed, this disclosure is not limited to the particular embodiments shown, but is instead to be accorded the widest scope consistent with the principles and features that are disclosed or suggested herein.

[0028] Although certain aspects, advantages, and features are described herein, it is not necessary that any particular embodiment include or achieve any or all of those aspects, advantages, and features. Some embodiments may not achieve the advantages described herein, but may achieve other advantages instead. Any structure, feature, or step in any embodiment can be used in place of, or in addition to, any structure, feature, or step in any other embodiment, or omitted. This disclosure contemplates all combinations and subcombinations of features from the various disclosed embodiments. No feature, structure, or step is essential or indispensable.

[0029] With the foregoing and other objects in view, and with reference to the diagrams that form part of this disclosure, Figures 1 -13 illustrate one example embodiment of an internal combustion engine which includes a plurality of cylinders (1) around a central axis and fixed as part of the engine housing (25). Figure 3 is a perspective view of the engine according to one embodiment. As shown in Figures 1 , within each fixed cylinder (1 ) is a pair of opposed pistons (2) that reciprocate to and from each partner piston where each plurality of pistons (2) are part of a single assembly. The entire engine contains four such assemblies comprising of two broadly concentric "intake" piston assemblies (3,5) ), which include inner intake piston assembly 3 (see Figure 5) and outer intake piston assembly 5 (see Figure 6) and two broadly concentric "exhaust" piston assemblies (4,6), which includes inner exhaust piston assembly 4 (see Figure 5) and outer exhaust piston assembly 6 (see Figure 6). In the illustrated embodiment, the pistons that are connected to the same assembly move in unison. With reference to Figure 5, the inner intake assembly 3 and inner exhaust assembly 4 are illustrated. With reference to Figure 6, the outer intake assembly 5 and outer exhaust assembly 6 are illustrated. Figure 4 is a front view of the inner and outer intake assemblies (3,5).

[0030] Each pair of opposing pistons reciprocate within a single cylinder (1 ). As shown in Figure 2, an inlet port (7) is positioned at one end of the cylinder and an exhaust port (8) is positioned at the opposite end of the cylinder. An aperture (9) is provided in the side wall and at the approximate center of the cylinder's length allowing for a spark-plug (1 1) to be exposed to an interior of the cylinder (1). The said ports (7,8) at each end of the cylinder being exposed as the pistons (2) reach the extremity of their strokes of which is accomplished via the said assemblies(3,4,5,6) coacting with two rotating cams (13, 14) with said cams (13, 14) being of generally sinusoidal form and circular and situated at opposite ends of the engine and affixed to cam mount plates (15, 16) that in turn affix to an output shaft (17) (see Figures 7-8) that passes through the center of the engine and where the "intake" end of the engine describes the end where pistons attached to the "intake" piston assemblies cyclically expose or occlude the inlet ports (7) (also referred to herein as "intake ports") and the "exhaust" end of the engine describes the opposite end of the engine where pistons attached to the "exhaust" piston assemblies cyclically expose or occlude the exhaust ports (8) (also referred to herein as "intake ports"), and where the "intake" cam (13) is affixed to an "intake" cam mount plate (15) that is affixed towards the "intake" end of the output shaft (17) at an appropriate location (18) and where the "exhaust" cam (14) is affixed to the "exhaust" cam mount plate (16) that is affixed to the "exhaust" end of the same output shaft (17) at an appropriate location (19). Thus, in the illustrated embodiment, the cylinders (1 ) can be stationary while the output shaft (17) rotates.

[0031] Thusly the operation of the system involves the reciprocating motion of the pistons (2) within each cylinder (1 ) causing the piston assemblies (3,4,5,6) to move parallel to the axis of the center output shaft (17) and whereby each of these four assemblies have regularly spaced cam rollers (20) that keep contact with the face of the cams (13, 14) at all times thereby causing the cams (13, 14) to rotate which in turn rotates the center output shaft (17). Each individual piston assembly has four regularly spaced cam rollers (20) and four pistons (2). [0032] As shown in Figure 1, the center output shaft (17) and cams (13, 14) are supported by radial ball bearings (21 ,22) with one radial ball bearing (21 ) located at the "intake" end of the engine and one radial ball bearing (22) located at the "exhaust" end of the engine.

[0033] With continued reference to Figure 1 and Figure 10, in the illustrated embodiment, encircling the "intake" radial bearing (21 ) is an "intake" linear bearing ring (23) and encircling the "exhaust" radial bearing (22) is an "exhaust" linear bearing ring (24) with both linear bearing rings (23,24) mounted on to the engine housing (25). To prevent rotation of the inner piston assemblies (3,4) [so described given the concentric arrangement of the assemblies], each linear bearing ring (23,24) embodies one half of a linear bearing assembly (26), the other half of the linear bearing assembly (27) is part of the inner piston assemblies (3,4) . A total of eight of these linear ball race assemblies are utilized in this manner between the linear bearing rings (23,24) and inner piston assemblies (3,4).

[0034] To prevent rotation of the "outer" assemblies (5,7) the housing (25) incorporates one half of a linear ball race assembly (41), the other half of the linear bearing assembly (42) is part of the outer piston assemblies (5,6). A total of eight of these linear ball race assemblies are utilized in this manner between the housing (25) and outer piston assemblies (5,6). Each linear bearing includes balls (43) as part of their respective assembly (26,27,41 ,42).

[0035] The said rotating output shaft (17) passes through the center of the engine supported by the radial bearings (21,22) allowing a flywheel (29) (or alternatively an armature or similar assembly depending on application) to be connected at one end (30) and allowing location (32)for a harmonic balancer (31 ) and location (34) for supercharger and auxiliary drive pulleys (33).

[0036] With reference to Figures 3 and 13, the intake manifold (35) is formed as part of the engine housing (25) and runs around the inner circumference of said housing (25) to enable aspiration to the plurality of cylinders (1 ), the airflow of which is effected via a supercharger (36). An idle speed controller (63) (see Figure 9) can be used to assist with smooth idle.

[0037] A charge of fuel is injected into the pressurized airflow and this mix enters the cylinders (1 ) at one end through intake ports (7) when exposed by the pistons (2) at that end of their stroke, and as these intake pistons and the exhaust pistons converge within each cylinder (1 ) creating compression and at the optimal point are ignited by a spark-plug (1 1 ) situated at the aperture (9) in the side of each cylinder between the compressing pistons (2), a separating force is applied to each pair of pistons within each cylinder.

[0038] In the illustrated embodiment herein, the said cams (13, 14) are positioned relative to each other so as to alter port timing so that the exhaust port (8) is closed before the intake port (7).

[0039] In the illustrated embodiment, the inner and outer piston assemblies (3,4,5,6) are positioned relative to each other so that they are always operating at opposite stages of the engine cycle.

[0040] In the illustrated embodiment and as shown in Figures 1 1 and 12, to facilitate the opposing motion between the "intake" inner piston assembly (3) and "intake" outer piston assembly (5) piston assemblies, eight rockers (37) are situated between the said assemblies (3,5) whereby the motion of one assembly forces the rocker to push the other assembly in the opposing direction. Skid plates (38) are positioned on each assembly to coact with each rocker (37). The curvature of the rockers can be tailored to complement the curvature of the "intake" cam (13) thereby ensuring the cam rollers (20) always remain in contact with the face of the cam (13).

[0041] Likewise, eight rockers (37) are similarly placed between the "exhaust" inner piston assembly (4) and "exhaust" outer piston assembly (6) thereby ensuring the cam rollers (20) always remain in contact with the face of the "exhaust" cam (14). The rockers (37) are affixed to the engine housing (25) through the use of rocker posts (39) at sixteen recessed locations (40) situated on the housing (25) between the cylinders (1 ).

[0042] Exhaust gases exit on either side of the housing (25) proximate to the exhaust ports (8 ) allowing for gases to leave the engine and in certain embodiments, drive a turbocharger to enhance performance and efficiency.

[0043] It can be seen that one advantage of the cams (13, 14) is that they can provide a programmable surface to tailor piston motion for each stroke so as to improve engine performance.

[0044] In the illustrated embodiments, the cam rollers (20) are in continuous rolling contact with their corresponding cam (13, 14) whereby reciprocation of the pistons (2) results from cyclical combustion of the fuel in the cylinders (1) or the coacting of the cam rollers (20) with the cams (13, 14).

[0045] It being apparent that components are housed within chambers at either end of the engine so that oil can be contained therein by use of seals (48,49) to lubricate all moving parts requiring oil lubrication. With reference to Figure 9, oil is fed from the sump (46) by a pump (45) that is driven by a pulley (56) that in turn is driven by a belt from a pulley (51 ) that is affixed to the center output shaft (17) through use of a drive pin (62). The engine housing (25) contains numerous oil galleys after passing through a filter (57) to feed oil into said chambers during engine operation in a manner consistent and similar with prior Art.

[0046] Scavenging is achieved by phasing the two cams (13, 14) in relation to one another thus enabling the pistons (2) part of the "exhaust" assemblies (4,6) to expose the exhaust port (8) prior to the pistons (2) part of the "intake" assemblies (3,5) exposing the inlet port (7) in a sequence so that combustion gases start to flow out of the exhaust whilst the inlet port (7) is still closed. As the "intake" and "exhaust" assemblies continue to move apart, the intake port (7) opens whilst the exhaust port (8) is still open and pressurized air is forced into each cylinder (1) driving exhaust gases out of the exhaust port (8) thus displacing exhaust gas from each cylinder (1 ) through the exhaust port (8) whilst pressurized air is admitted through the intake port (7).

[0047] As the pistons (2) move through their Bottom Dead Center (BDC) locations and reverse direction, the exhaust port (8) is closed by the "exhaust" piston and scavenging ceases. The intake port (7) remains open whilst the "intake" piston continues and moves away from BDC. This cycle occurs in unison within each cylinder where the pistons (2) are connected to the same opposing piston assemblies (3 and 4, or 5 and 6).

[0048] In the illustrated embodiments, each piston (2) has a cylindrical operative end to be fitted with piston rings (not shown) while its inoperative end is attached to an assembly (3,4,5,6) that incorporates a suitable number of rollers (20). The piston rings engage in the bores of their respective cylinders (1). Each cam roller (20) is part of a piston assembly (3,4,5,6) as previously described and mounted rotatably on a cam pin (47) having its axis at right angles to the axis of the center output shaft (17). The piston dwell can be set at any duration through the profiling of each cam' s sinusoidal undulations or alternatively, by rotating the cams relative to each other about the axis of the center output shaft (17).

[0049] In the illustrated embodiment, each cam (13, 14) undulates between high and low sections with the profiling of this undulation used to effect the most optimum or desired reciprocation of the pistons (2) within their respective cylinder (1 ) thereby enabling the engine to follow its two-stroke cycle and optimise scavenging as the engine's pistons (2) cyclically expose or occlude the intake and exhaust ports (7,8). The cams are characterized by four high and four low sections that result in each cylinder firing four times per cam revolution. In certain embodiments, the curvature of these undulations will also result in the pistons momentarily moving in the same direction thereby delaying further compression of the charge before ignition occurs at the optimum moment.

[0050] In the illustrated embodiments, temperature control is achieved through circulation of coolant throughout the housing (25) using chambers that encircle all cylinders (1) with the said chamber being separated into a combustion segment and exhaust segment of the housing (25) with separate thermostats and exiting through a coolant outlet (61) and reenters the engine through inlet (60). Coolant can be re- circulated throughout the engine once it has passed through a suitable heat exchanger.

[0051] A hall effect sensor (55) and trigger wheel (50) is used to determain the position of the engine within a cycle in order to electronically control the timing of the spark and fuel delivery to the engine.

[0052] The many design modifications set out illustrate that the embodiments are given by way of example only and may be subject to many further variations as will be readily apparent to persons skilled in the Art and without departing from the scope and ambit of the disclosure, as defined in this description and the referenced diagrams.

[0053] Certain Terminology

[0054] Conditional language, such as "can," "could," "might," or "may," unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and/or steps are included or are to be performed in any particular embodiment.

[0055] Conjunctive language such as the phrase "at least one of X, Y, and Z," unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z.

[0056] Unless otherwise explicitly stated, articles such as "a" or "an" should generally be interpreted to include one or more described items. Accordingly, phrases such as "a device configured to" are intended to include one or more recited devices. Such one or more recited devices can also be collectively configured to carry out the stated recitations. For example, "a processor configured to carry out recitations A, B, and C" can include a first processor configured to carry out recitation A working in conjunction with a second processor configured to carry out recitations B and C.

[0057] The terms "comprising," "including," "having," and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Likewise, the terms "some," "certain," and the like are synonymous and are used in an open-ended fashion. Also, the term "or" is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term "or" means one, some, or all of the elements in the list.

[0058] The terms "approximately," "about," and "substantially" as used herein represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, in some embodiments, as the context may dictate, the terms "approximately", "about", and "substantially" may refer to an amount that is within less than or equal to 10% of the stated amount. The term "generally" as used herein represents a value, amount, or characteristic that predominantly includes, or tends toward, a particular value, amount, or characteristic. As an example, in certain embodiments, as the context may dictate, the term "generally parallel" can refer to something that departs from exactly parallel by less than or equal to 20 degrees and/or the term "generally perpendicular" can refer to something that departs from exactly perpendicular by less than or equal to 20 degrees.

[0059] Overall, the language of the claims is to be interpreted broadly based on the language employed in the claims. The claims are not to be limited to the non exclusive embodiments and examples that are illustrated and described in this disclosure, or that are discussed during the prosecution of the application.

[0060] Summary

[0061] Although this disclosure describes certain embodiments and examples of engines and methods, many aspects of the above-described systems and methods may be combined differently and/or modified to form still further embodiments or acceptable examples. All such modifications and variations are intended to be included herein within the scope of this disclosure. Indeed, a wide variety of designs and approaches are possible and are within the scope of this disclosure. For example, although the engine shown in the figures have a certain number of cylinders however in other embodiments the engine may include more or less cylinders .

[0062] Also, although there may be some embodiments within the scope of this disclosure that are not expressly recited above or elsewhere herein, this disclosure contemplates and includes all embodiments within the scope of what this disclosure shows and describes. Further, this disclosure contemplates and includes embodiments comprising any combination of any structure, material, step, or other feature disclosed anywhere herein with any other structure, material, step, or other feature disclosed anywhere herein.

[0063] Furthermore, certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a subcombination or variation of a subcombination. [0064] For purposes of this disclosure, certain aspects, advantages, and features are described herein. Not necessarily all such aspects, advantages, and features may be achieved in accordance with any particular embodiment. For example, some embodiments of any of the various disclosed systems include the container and/or include pluralities of the container; some embodiments do not include the container. Those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

[0065] Some embodiments have been described in connection with the accompanying drawings. The figures are drawn to scale, but such scale should not be interpreted to be limiting. Distances, angles, etc. are merely illustrative and do not necessarily bear an exact relationship to actual dimensions and layout of the devices illustrated. Components can be added, removed, and/or rearranged. Further, the disclosure herein of any particular feature, aspect, method, property, characteristic, quality, attribute, element, or the like in connection with various embodiments can be used in all other embodiments set forth herein. Also, any methods described herein may be practiced using any device suitable for performing the recited steps.

[0066] Moreover, while components and operations may be depicted in the drawings or described in the specification in a particular arrangement or order, such components and operations need not be arranged and performed in the particular arrangement and order shown, nor in sequential order, nor include all of the components and operations, to achieve desirable results. Other components and operations that are not depicted or described can be incorporated in the embodiments and examples. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations. Further, the operations may be rearranged or reordered in other implementations. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products.

[0067] In summary, various illustrative embodiments and examples of engine and methods have been disclosed. Although the engine and methods have been disclosed in the context of those embodiments and examples, this disclosure extends beyond the specifically disclosed embodiments to other alternative embodiments and/or other uses of the embodiments, as well as to certain modifications and equivalents thereof. This disclosure expressly contemplates that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another. Accordingly, the scope of this disclosure should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow as well as their full scope of equivalents.

Claims

WHAT IS CLAIMED IS:

1 . A barrel internal combustion engine comprising:

an output shaft;

a plurality of cylinders positioned around the output shaft; each cylinder included a pair of opposed intake and exhaust pistons that oppose each other and which are configured reciprocate to and from each opposed intake or exhaust piston; the plurality of cylinders each including an intake side and an exhaust side corresponding to the exhaust and intake pistons positioned therein;

a pair of concentric exhaust piston assemblies comprising an inner exhaust piston assembly and an outer exhaust piston assembly, the inner exhaust piston assembly being coupled to at least one of the exhaust pistons and the outer exhaust piston assembly being couple to a different one of the exhaust pistons;

an exhaust cam coupled to the output shaft and the inner and outer exhaust piston assemblies, the exhaust cam configured rotate in response to reciprocal linear movement of the inner and outer exhaust piston assemblies;

a pair of concentric intake piston assemblies comprising an inner intake piston assembly and an outer intake piston assembly, the inner intake piston assembly being coupled to at least one of the intake pistons and the outer exhaust piston assembly being couple to at least a different one of the intake pistons; and

an intake cam coupled to the output shaft and the inner and outer intake piston assemblies, the intake cam configured rotate in response to reciprocal linear movement of the inner and outer exhaust piston assemblies.

2. The barrel internal combustion engine of Claim 1 wherein the engine is a two stroke engine and each cylinder includes an intake port and an exhaust port and wherein the associated intake piston cyclically exposes the intake port and the associated exhaust piston cyclically exposes the exhaust port.

3. The barrel internal combustion engine according to Claim 2, comprising an intake manifold that forms a common plenum that surrounds the plurality of cylinders and their associated intake ports.

4. The barrel internal combustion engine of Claim 3, wherein the intake housing is integrally formed with a housing of the engine.

5. The barrel internal combustion engine according to any one of Claims 1-4 further comprising at least one rocker positioned between the inner exhaust piston assembly and the outer exhaust piston assembly, wherein motion of one the inner exhaust piston assembly and the outer exhaust piston assembly forces the rocker to push the other assembly in an opposing direction.

6. The barrel internal combustion engine according to any one of Claims 1 -5 further comprising at least one rocker positioned between the inner intake piston assembly and the outer intake piston assembly, wherein motion of one the inner intake piston assembly and the outer intake piston assembly forces the rocker to push the other assembly in an opposing direction.

7. The barrel internal combustion engine according to any one of Claims 1 -6 wherein each of the inner and outer intake assemblies includes at least one cam roller that contacts a face of the intake cam.

8. The barrel internal combustion engine according to Claim 7, wherein there is at least one cam roller associated with each intake piston coupled to the inner and outer intake assemblies

9. The barrel internal combustion engine according to any one of Claims 1-8 wherein each of the inner and outer exhaust assemblies includes at least one cam roller that contacts a face of the exhaust cam.

10. The barrel internal combustion engine according to Claim 9, wherein there is at least one cam roller associated with each intake piston coupled to the inner and outer intake assemblies.

1 1 . The barrel internal combustion engine according to any one of Claims 1 -10, wherein the intake pistons coupled to the inner intake assembly are out of phase with the intake pistons coupled to the outer intake assembly.

12. The barrel internal combustion engine according to any one of Claims 1 -1 1 , wherein the exhaust pistons coupled to the inner exhaust assembly are out of phase with the exhaust pistons coupled to the outer exhaust assembly.

13. The barrel internal combustion engine according to any one of Claims 1 -12, wherein the intake cam and the exhaust cam each form undulated circular surfaces.