Patent Publication Number: US-8522732-B2

Title: Flywheel for barrel engine

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This utility patent application claims priority from U.S. provisional patent application Ser. No. 61/325,912, filed Apr. 20, 2010, and U.S. provisional patent application Ser. No. 61/171,566, filed Apr. 22, 2009, the entire content of both of which are incorporated herein in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a flywheel for a barrel engine and a barrel engine incorporating this flywheel. 
     BACKGROUND OF THE INVENTION 
     Internal combustion engines are widely used for driving a variety of vehicles. Internal combustion engines come in a variety of configurations, which are typically aptly named for the particular orientation or arrangement of the reciprocating pistons and cylinders in the engines. One example of an internal combustion engine is a “V” type engine, in which the “V” refers to the arrangement of the cylinders in rows that are angled relative to each other to form a V shape. Another type of internal combustion engine that is most relevant to the invention is a barrel-type engine. 
     Barrel engines typically include a plurality of cylinders and pistons arranged in the form of a “barrel” in which their axes are parallel to each other and arranged along a circle concentric with the power output shaft. Power is transmitted from the reciprocating pistons to a cam plate via a sliding or roller interface. The cam plate&#39;s nominal plane is perpendicular to the piston axes and attached to the output shaft. One variation, commonly referred to as a double-ended barrel engine, typically uses a double-ended piston construction and utilizes piston and rod assemblies that have power cylinders at each end. Another configuration of the barrel engine concept, commonly known as a single-ended barrel engine, only uses power cylinders at one end. 
     SUMMARY OF THE INVENTION 
     An internal combustion barrel engine has an engine housing and an elongated longitudinal output shaft defining a longitudinal axis of the engine. A plurality of cylinders are defined in the engine housing and disposed about the longitudinal output shaft. Each of the cylinders has a cylinder axis that is generally parallel to the longitudinal axis of the engine. Each cylinder has a closed end adjacent the first end of the housing and an opposite open end. A cam plane is defined perpendicular to the longitudinal axis and disposed between the open ends of the cylinders and the second end of the engine housing. A cam plate is disposed in the engine housing and supported for rotation about the longitudinal axis. The cam plate has a central portion and a cam portion extending outwardly therefrom. The cam portion has at least one cam surface that undulates from one side of the cam plane to the other. A flywheel has a plurality of lobes, each lobe being disposed generally in alignment with an area where the cam surface undulates closest to the open end of a cylinder. 
     In some versions, each flywheel lobe has a curved surface directed toward the cam surface of the cam plate. The cam portion may have a curved surface directed away from the cylinders with the curved surface of each flywheel lobe being generally parallel to the curved surface of the cam portion. 
     In some embodiments, the cam plate has two areas where the cam surface is disposed on the side of the cam plane closest to the open end of the cylinders, and the flywheel has two lobes. 
     In some embodiments, the lobes of the flywheel each have a longitudinally thickest portion, the thickest portion being longitudinally aligned with the area where the cam surface undulates closest to the open end of a cylinder. 
     In some embodiments, the flywheel has a radial outer edge defining the maximum radius of the flywheel, and each of the lobes extends to the radial outer edge. A gap is defined between each lobe, the gap being defined at the radial outer edge. 
     In further embodiments, a connection portion extends between each of the lobes, the connection portions each having a longitudinally thickness less than the longitudinal thickness of the lobes. 
     In certain embodiments, the flywheel has a hub, the hub being directly connected to the central portion of the cam plate. In some versions, the output shaft extends through the central portion of the cam plate and the central portion of the cam plate is interconnected with the output shaft such that the cam plate and output shaft are coupled for rotation about the longitudinal axis and the cam plate is longitudinally slidable with respect to the output shaft. 
     In another embodiment, an internal combustion barrel engine has an engine housing with a first end and an opposite second end. An elongated longitudinal output shaft is disposed in the engine housing and defines a longitudinal axis of the engine. A plurality of cylinders are defined in the engine housing and disposed about the longitudinal output shaft. Each of the cylinders has a cylinder axis that is generally parallel to the longitudinal axis of the engine. Each of the cylinders has a closed end adjacent the first end of the housing and an opposite open end. A cam plane is defined perpendicular to the longitudinal axis and disposed between the open ends of the cylinders and the second end of the engine housing. A cam plate is disposed in the engine housing and supported for rotation about the longitudinal axis. The cam plate has a central portion engaged with the output shaft and a cam portion extending outwardly therefrom. The cam portion has at least one cam surface that undulates from one side of the cam plane to the other. A flywheel generally fills an area defined between a curve parallel to the undulating cam surface and a plane parallel to the cam plane. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of an embodiment of a internal combustion barrel engine with portions cut away so as to show internal components; 
         FIG. 2  is a cross sectional side view of the barrel engine of  FIG. 1 ; 
         FIG. 3  is a detailed cross sectional side view of a portion of the barrel engine showing the cam plate and output shaft, along with an optional variable compression ratio device; 
         FIG. 4  is an enlarged side view of a portion of the cam plate and power output shaft with much of the engine housing cut away; 
         FIG. 5  is an enlarged perspective view of one end of the cam plate and output shaft; 
         FIG. 6  is an enlarged perspective view of the other end of the cam plate and output shaft; 
         FIG. 7  is an exploded perspective view of a portion of the engine showing the flywheel, cam plate and a portion of the output shaft; 
         FIG. 8  is an end view of an embodiment of a flywheel for use with the present invention; 
         FIG. 9  is a cross sectional view of the flywheel of  FIG. 8 ; 
         FIG. 10  is a perspective view of the flywheel of  FIGS. 8 and 9 ; 
         FIG. 11  is a perspective view of the opposite side of the flywheel; and 
         FIG. 12  is a view of an alternative flywheel embodiment for use with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In an internal combustion barrel engine, it is necessary to include a flywheel to maintain rotational inertia and for other reasons. In typical internal combustion engines, a flywheel is a simple disk attached to an end of the crankshaft. A barrel type engine presents special challenges in packaging a flywheel, especially if the engine is compact. The present invention provides a flywheel that uses the “wasted” spaced adjacent the undulating cam plate. This flywheel may have multiple lobes with each lobe being positioned in areas where the cam plate leaves space. Alternatively, the flywheel may be plate shaped with thicker portions in the areas where space is available. In some embodiments, the flywheel is directly fixed to the cam plate to avoid transmission of varying loads through the power shaft. This is especially beneficial when the cam plate slides on the power shaft to allow variable compression ratios. 
     In some embodiments of the present invention, the cam plate and the power shaft are separate elements that are mechanically coupled such that they rotate together. In further embodiments, the cam plate is mechanically coupled to the power shaft such that the cam plate is longitudinally slidable relative to the output shaft and the engine housing. By varying the longitudinal position of the cam plate relative to the engine housing, the compression ratio of the engine may be varied. A variable compression ratio device may be provided for adjusting longitudinal position of the cam plate relative to the engine housing. The combination of a sliding joint between the cam plate and output shaft with a variable compression ratio device allows the compression ratio to be adjusted without changing the longitudinal position of the output shaft. An embodiment of the present invention is described below which includes variable compression ratio features and a flywheel in accordance with the present invention. It should be understood that the present invention is not limited to this embodiment. 
       FIG. 1  is a perspective view and  FIG. 2  is a side view of an internal combustion barrel engine  10  according to an embodiment of the present invention with portions cut away to show the internal components. The engine  10  includes a plurality of piston assemblies  12  and cylinders  14  each having axes that are generally parallel with a power output shaft  16 . The cylinders are provided by an engine housing or block  15 . The engine housing  15  may be said to have a longitudinal bore for receiving the power output shaft. The power output shaft  16  may be said to define a longitudinally extending axis of rotation A. The pistons  12  and cylinders  14  are arranged in a circular formation concentric with the power output shaft  16 . 
     Each piston assembly  12  includes a piston  18  disposed in a cylinder  14  and a rod  20  extending longitudinally from the piston  12 . 
     In the illustrated embodiment, the piston assembly  12  includes a cross head bearing assembly  22  which is pivotally interconnected to the distal end of the rod  20 . In alternative embodiments, the interconnection between the piston assembly and the cam plate may be provided in other ways, including single or double roller elements or sliding mechanisms. Further, the piston rod  20  may be rigidly interconnected with the bearing or sliding mechanism and/or the piston rod and bearing housing may be integrated into a single component. 
     In the illustrated embodiment, a cam plate  30  is received on the power shaft  16 . The cam plate  30  includes a central portion  32  adjacent the power shaft  16  and a cam portion  34  that extends radially outwardly therefrom. In this embodiment, the cam portion  34  has a pair of opposed cam surfaces  36  and  38  which both may be said to be non-planar undulating cam surfaces. The bearing assembly  22  has a pair of rollers which engage the surfaces  36  and  38 . As such, as combustion forces reciprocate the piston assemblies  12 , the cam plate  30  rotates about the longitudinal axis A of the engine. As will be clear to those of skill in the art, the undulating cam portion  34  leaves some space in the areas where the cam portion undulates closest to the open ends of the cylinders. As shown, a flywheel  110  may be partially packaged in these areas. This allows the overall engine length to be similar with or without the flywheel  110 , since the flywheel is mainly packaged in otherwise wasted space. 
     Referring now to  FIG. 3 , a detailed cross sectional side view of a portion of the barrel engine is provided, showing the cam plate  30  partially cut away. This figure illustrates a pair of rollers  40  and  42  engaging the cam surfaces  36  and  38  respectively. As shown, the power output shaft  16  is an elongated shaft that extends through a bore  44  defined longitudinally through the central portion  32  of the cam plate  30 . Preferably, the cam plate  30  is mechanically coupled to the output shaft  16  such that they rotate together about the longitudinal axis A. The bore  44  in the central portion  32  of the cam plate  30  may be said to have an inner surface with engagement elements defined thereon. In the embodiment illustrated in  FIG. 3 , the engagement elements are radial splines  46  that extend inwardly from the inner surface of the bore  44 . The output shaft  16  has corresponding engagement elements defined on an outer surface of the output shaft  16 . In the embodiment illustrated in  FIG. 3 , the engagement elements are radial splines  48  that extend outwardly from the outer surface of the shaft  16  and engage the splines  46  of the cam plate  30 . As will be clear to those of skill in the art, the mechanical coupling between the cam plate  30  and the shaft  16  may take other forms, or the cam plate may be integral with the shaft  16 . 
     In the embodiment shown, it is preferred that the mechanical coupling between the cam plate and shaft couple the cam plate and shaft together for rotation about the axis A, but allow the cam plate to be moved or slid longitudinally relative to the shaft. As such, the mechanical coupling between the cam plate and shaft substantially prevents relative rotational motion between the plate and shaft but allows relative longitudinal movement. 
     As discussed previously, preferred embodiments of the present invention may utilize a variable compression ratio device to adjust the longitudinal position of the cam plate  30  relative to the shaft  16  and housing  15 . The mechanical coupling just discussed allows the longitudinal position on the cam plate  30  to be adjusted without changing the longitudinal position of the shaft  16 .  FIG. 3  illustrates an actuator  60  disposed between one end of the cam plate  30  and the engine housing  15 . The actuator  60  is operable to apply longitudinal force to one end of the cam plate  30 , via an intermediary element  62 , thereby changing the longitudinal position of the cam plate  30 . As will be clear to those of skill in the art, the variable compression ratio device may take a variety of forms other than the actuator  60  shown. Though not shown, the engine may further include a biasing element for biasing the cam plate  30  such that it remains in contact with the variable compression ratio device. 
     As will be clear to those of skill in the art, the forces transmitted between the piston assemblies and the cam plate  30  may be substantial. These forces act in a direction that would cause the cam plate  30  to rock with respect to the shaft  16  if the cam plate  30  were not supported. For operation of a variable compression ratio device, it is preferred that these rocking forces not be transmitted from the cam plate  30  to the shaft  16 . If these forces are transmitted from the plate to the shaft, these forces will make it more difficult to longitudinally move the cam plate  30 . For example, such forces may lead to binding in the mechanical coupling between the plate and shaft. 
     In some embodiments, the cam plate  30  is directly supported by the engine housing to counteract these rocking forces. Referring now to  FIG. 4 , an enlarged side view is provided of the cam plate  30  with much of the remainder of the engine removed for clarity. In this embodiment, the central portion  32  of the cam plate  30  has a base portion  70  that extends towards one end of the engine and an opposite top portion  72  that extends towards the other end of the engine. A pair of spaced apart bearing surfaces  74  and  76  are provided on the outer surfaces of the base portion  70  and top portion  72 , respectively. The engine housing  15  has a corresponding pair of spaced apart bearing surfaces  78  and  80  in what may be called a longitudinal bore  82  that extends through the engine housing. When the output shaft  16  and cam plate  30  are disposed in the longitudinal bore of the engine housing  15 , the bearing surfaces  74  and  76  on the outer surface of the central portion  32  of the cam plate  30  are generally aligned with the bearing surfaces  78  and  80  on the inner surface of the bore  82  in the engine housing  15 . As shown, bearing journal members  82  and  84  may be provided on the outer surface of the central portion  32  of the cam plate and/or the inner surface of the bore  82  of the housing  15  such that the bearing journal members define the bearing surfaces. In the illustrated embodiment, the bearings take the form of traditional engine journal bearings. Alternatively, the bearings may take the form of ball or roller bearings. However, it is preferred that the bearings defined between the cam plate  30  and engine housing  15  allow longitudinal movement of the cam plate  30  relative to the housing  15 . The bearings are typically fed with pressurized oil. 
     The engine housing  15  is typically formed as multiple pieces and the bearing surfaces may be formed by elements that are interconnected with the remainder of the housing. For example, a bearing support element is shown at  86 . This bearing support element may be considered as part of the engine housing for purposes of the present invention. 
       FIG. 5  provides an enlarged perspective view of the top portion  72  of the cam plate  30 , while  FIG. 6  provides an enlarged perspective view of the base portion  70  of the cam plate  30 . Certain portions of the engine, such as the flywheel, are left out of  FIGS. 4-6  to simplify the drawing. 
     Referring again to  FIG. 3 , it is preferred that the elongated power output shaft  16  be supported by an additional pair of spaced apart bearings. The engine housing  15  may be said to have a second pair of spaced apart bearing surfaces  90  and  92  defined on the inner surface of the bore of the housing  15 . The shaft  16  has a pair of corresponding spaced apart bearing surfaces  94  and  96  defined on the outer surface of the shaft  16 . The bearing surfaces  90  and  94  and the bearing surfaces  92  and  96  are generally aligned so as to rotationally support the shaft  16 . Once again, bearing journal members may be provided so as to define one or both of the bearing surfaces, or ball or roller bearings may be provided. Preferably, the bearings are provided with pressurized oil, such as by the oil holes  98  shown in shaft  16 . Alternatively, the pressurized oil may be provided to the bearings from the housing  15  with pressurized oil being fed through one or more of the holes in the shaft and from there being provided to the mechanical coupling, such as the splines  46  and  48 . 
     Referring now to  FIGS. 7-11 , the flywheel  110  is shown in more detail.  FIG. 7  provides an exploded view of the power shaft  16 , the cam plate  30  and the flywheel  110 . As will be clear to those of skill in the art, the cam plate undulates closer to and then farther from the open ends of the cylinders. It may be said to undulated back and forth across a cam plane B that is defined perpendicular to the longitudinal axis A. The plane B may be positioned such that half of the cam portion  34  is on one side and half is on the other. Where the cam plate undulates closer to the open ends of the cylinders, there is space left unutilized. The flywheel  110  has lobes  112  and  114  that fill this space. 
     In the illustrated embodiment, the flywheel lobes have a first surface  116  that is directed toward the cam surface  38  and an opposite second surface  118  that is directed away from the cam surface  38 . In the illustrated embodiment, the first surface generally follows a curve parallel to the cam surface  38  and the opposite second surface  118  is generally parallel to the cam plane B.  FIG. 9  shows one shape of the second surface  118 , and it can be seen that it is generally parallel to the cam plane. 
     The flywheel  110  also has a central hub  120 . The lobes  112  and  114  are connected to the hub and extend radially outwardly therefrom. The flywheel has a radial outer edge  122  defining the maximum radius of the flywheel. Each of the lobes extends to this radial outer edge  122 . Gaps  124  and  126  are defined between the lobes  112  and  114 . As shown, the gaps are cutouts where the flywheel  110  does not have any material extending outwardly as far as the outer edge  122 . 
     The flywheel lobes  112  and  114  may also be described as each being disposed generally in alignment with an area where the cam surface undulates closest to the open ends of the cylinders, which is also furthest from the flywheel overall. One such area of the cam surface  38  is indicated at  130  in  FIG. 7 . As shown, the portion of the flywheel lobe  112  that is thickest in the longitudinal direction (parallel to axis A) is longitudinally aligned with the area  130  and the flywheel tapers to be thinner towards its opposed ends  132  and  134 . 
     As best shown in  FIG. 7 , the illustrated embodiment of the flywheel  110  is attached directly to the central portion  32  of the cam plate  30  using a plurality of fasteners  136 . This is a preferred arrangement, since the rotational inertial loads are passed directly between the cam plate and the flywheel rather than passing through the power shaft. This is especially preferred in embodiments wherein the cam plate  30  is longitudinally movable with respect to the power shaft  16 , as discussed earlier. As will be clear to those of skill in the art, the flywheel may be connected with the cam plate and/or power shaft in ways other than illustrated. 
     Other shapes are also possible for the flywheel. The flywheel may be a complete plate or ring with thicker areas where space allows.  FIG. 12  illustrates such an alternative embodiment of a flywheel  140 . As shown, the flywheel  140  has lobes  142  and  144  but, unlike the earlier embodiment, connection portions  146  and  148  extend between the lobes, eliminating the gap present in the earlier embodiment. As will be clear to those of skill in the art, this configuration will take slightly more room in the engine, but may be beneficial for some applications. The lobes may also have other shapes. For example, the lobes may be each rectangular shaped when viewed from the side, if such a shape provides sufficient rotational mass. 
     The illustrated embodiment is for a barrel engine design in which the cam plate undulates towards the open ends of the cylinders in two areas, and therefore the flywheel has two lobes. As will be clear to those of skill in the art, the cam plate may have three or more areas where it undulates closest to the open ends of the cylinders, and a flywheel according to the present invention will preferably include a matching number of lobes. 
     The invention has been described in an illustrative manner. It is, therefore, to be understood that the terminology used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the invention are possible in light of the above teachings. Thus, within the scope of the appended claims, the invention may be practiced other than as specifically described.