Patent Publication Number: US-2010108034-A1

Title: Rotary Engine

Description:
FIELD OF THE INVENTION 
     The present invention relates to internal combustion engines, and is more particularly concerned with such engines categorised as rotary engines. 
     BACKGROUND OF THE INVENTION 
     Conventional internal combustion engines employ one or more cylinders in each of which reciprocates a piston driven by the explosive power generated by the combustion of a fuel triggered by the use of either a spark or compression. The power so produced is used to drive a shaft for use in traction, for example in motor vehicles, or for static use in other machinery or indeed to produce more power, for example by the deployment of a generator. 
     Various proposals have been made to vary this manner of operation, for example the Wankel Engine which uses one or more specially shaped rotors mounted on a drive shaft, fuel being combusted to provide the motive power to turn the rotor(s) to drive the shaft. Another example of a rotary engine was that used in some early military planes during the First World War, the characterizing feature being that the piston casing drove the propeller, rather than the crankshaft per se. Other rotary engines were tested in prototypic form in motor cycles and in early road vehicles. The principal surviving type of rotary engine is the Wankel Engine a version of which remains commercially available in Mazda® cars. 
     An advantage of rotary engines is the enhanced power-to-weight ratio compared to conventional internal combustion engines and improved balance. However, cost is an important factor and generally with commercially produced units, the degree of sophistication dictates a high production cost burden reflected in the selling price. 
     Accordingly, there is a need for an improved rotary engine displaying the advantages associated with engines of this general type but of low manufacturing cost and thus affordable product sales price. 
     SUMMARY OF THE INVENTION 
     It is therefore a general object of the present invention to provide an improved rotary engine. 
     It is a further object of the present invention to propose such an engine in which there are unique constructional and operational elements at an economic manufacturing cost, resulting in reliability and efficiency available to consumers at a competitive and affordable price. 
     A still further object of the present invention is to provide a rotary engine of essentially modular construction, thus allowing of ease of replacing parts and interchangeability. Additionally, the modular construction affords versatility in power train design and function. 
     Moreover, an important object of the present invention is to provide a rotary engine with enhanced balance, low friction and low noise output. 
     According to the invention, a rotary engine is characterised by a cylinder casing, a cylinder axially rotatable within the casing, a cylinder head rotatable with and affixed to the top of the cylinder, at least one aperture provided in the cylinder head, a valving block fixed to the casing and registering with the cylinder head to provide associated ports, a piston reciprocable within the cylinder, at least two contra-rotatable crank shafts each having at least one throw, a connecting rod attached to each throw of the corresponding crankshaft and to the piston, a gear cage base attached to the cylinder, a pinion rigid with each crank shaft and rotatably mounted in said base for rotation in opposite senses, a fixed gear ring attached to the casing, each pinion meshing with the gear ring, and an outlet shaft connected to the gear cage base. 
     Conveniently, each pinion is in the form of a bevel gear and the fixed gear ring is correspondingly bevel-toothed. 
     A crank casing is provided and is attached at the end of the cylinder casing remote from the valving block, the cylinder casing housing the crankshafts and the gear cage and the gear ring being sandwiched and fixed between the cylinder casing and the crank casing, extending into the latter at the periphery thereof. 
     A gear cage base has bearing races provided for each of the crankshafts and a connection for the output shaft. 
     The gear cage base joins with a gear cage cradle forming the cylinder end remote from the valving block such that in use the cylinder and the piston rotate about their longitudinal axes as the gears are turned by the crankshafts with the gears meshing with the fixed gear ring. 
     The output shaft may be simply connected to the gear cage base or in the alternative an epicyclic gear assembly may be provided for the output shaft. A suitable bearing race is preferably provided in the gear cage base for the output shaft. 
     Each crankshaft may be provided with a counterweight for each throw. 
     The cylinder head is provided with suitable aperture(s) which in use sequentially register with corresponding inlets and outlets in the valving block, rotation of the cylinder in relation to the block bringing such registration in the appropriate sequence dictated by whether the internal combustion engine is four-stroke or two-stroke. 
     Other objects and advantages of the present invention will become apparent from a careful reading of the detailed description provided herein, with appropriate reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further aspects and advantages of the present invention will become better understood with reference to the description in association with the following Figures, in which similar references used in different Figures denote similar components, wherein: 
         FIG. 1  is a side sectional view of a rotary engine in accordance with an embodiment of the present invention showing the piston at bottom dead centre within its cylinder; 
         FIG. 2  is a view corresponding to that of  FIG. 1  but showing the piston at top dead centre; 
         FIG. 3  is a perspective external view of the rotary engine depicted in  FIGS. 1 and 2 ; 
         FIG. 4  is a cross-sectional view of the rotating parts of the rotary engine with the piston at bottom dead centre; 
         FIG. 5  is a cross-sectional view of the two crankshafts at bottom dead centre; 
         FIG. 6  is a cross-sectional view similar to  FIG. 5  of an alternative drive shaft; 
         FIG. 7  is a view of the crankshafts, connecting rods and drive gears at mid-stroke of the piston in its cylinder; 
         FIG. 8  is a cross-sectional view along the line B-B in  FIG. 9 ; 
         FIG. 9  is a view of the piston and crankshafts with connecting rods at mid-stroke of the piston in its cylinder; 
         FIG. 10  is a perspective view of the piston and cranking assemblies at mid-stroke; 
         FIGS. 11-15  are detailed views of the valving arrangements; 
         FIG. 11  is a view on the line A-A of  FIG. 12  showing the end of the cylinder head; 
         FIG. 12  is a view of the valve block assembly; 
         FIG. 13  is an exploded view of the valving arrangements and the cylinder; 
         FIG. 14  is a view of the intake and exhaust valving arrangements along the line C-C of  FIG. 15 ; 
         FIG. 15  is a view of an assembled rotary engine in accordance with the present invention; 
         FIG. 16  is a perspective view of all the rotating parts of the engine assembled with a planetary gear box for the outlet shaft; and 
         FIG. 17  is a similar view to that of  FIG. 16  but with a simple outlet shaft arrangement of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the annexed drawings the preferred embodiments of the present invention will be herein described for indicative purpose and by no means as of limitation. 
     Reference is now made to  FIGS. 1 and 2  in which a rotary engine in accordance with an embodiment of the present invention is shown generally at  1  and comprises a cylinder or engine casing  22  accommodating within its cavity a rotatable cylinder  26  provided with cooling fins  85  which are a snug fit to ensure smooth rotary movement of the cylinder  26  within the said cavity. The cylinder  26  is provided with a cylinder head  27  having a suitable aperture  28  as described hereinafter. 
     A crank casing  24  is attached to the cylinder casing  22 , with a gear ring  88  therebetween, as shown and provides an outlet ball race  31  for an output shaft  30 . 
     The cylinder  26  at its end remote from the head  27  forms a gear cage cradle  29  attaching to a gear cage cradle base  32  and a crankshaft outer support  36 , the bearing  44  being provided between both the cradle  29  and the base  32 , and the crankshafts  70 ,  80 . In  FIGS. 1 and 2  an epicyclic gearbox  40  is attached to the gear cage base  32  in the region of the bearing  44 , the output shaft  30  having teeth  60  at its relatively inner end for meshing engagement with the other gears of the box, the shaft  30  extending from this gearbox  40 . In other embodiments, for example as shown in  FIG. 6 , a simple connection, such as a mechanical joint, is made between the shaft  30  and the gear cage base  33  for the transmission of power. 
     A piston  50  is reciprocable within the cylinder  26 , which defines a combustion space  51  as referenced in  FIG. 1 . The piston  50  is carried through the agency of a piston pin  52  by two connecting rods  48 ,  49  which extend from respective throws or crank pins  45 ,  47  carried on two separate and contra-rotating crankshafts  70 ,  80 . Each of the shafts  70 ,  80  carries a bevel gear pinion  10 ,  12  respectively, which in turn meshes with the bevel gear ring  88  fixed between the cylinder casing  22  and the crank casing  24 . The shafts  70 ,  80  are carried in bearings  90 ,  92  in the crankshaft support  36  and are also mounted in bearings  44 , as shown more particularly in  FIGS. 7 and 8 . 
       FIG. 9  illustrates in particular that the connecting rods  48 ,  49  act individually and translate contra-rotation to the respective crankshafts  70 ,  80 . This figure also shows the engine with its piston at mid stroke position with the connecting rods  48 ,  49  allowing significant reduction of the side loading from the piston  50  and the wall of cylinder  26  (not shown in this view). 
       FIGS. 11 to 15  show three components which constitute the valving arrangements for the engine  1 .  FIG. 11  shows a cylinder head  27  in the form of a disc which rotates with the cylinder  26  during its rotation, the head having an aperture  28  intended to register sequentially with appropriate inlet and outlet ports in a fixed valving block  78  held in one end of the cylinder casing  22 . The valving block  78  includes at least two (one inlet and one outlet—for a diesel-type engine), typically three ports (one inlet, one outlet and one ignition—for a spark ignition-type engine), as shown herein. Whilst the present embodiment relates to a four-stroke engine, a two-stroke engine is possible by varying the number of apertures  28 . 
     In  FIGS. 13 to 15 , and more specifically in  FIG. 13  an exploded view of the valving arrangement of the present invention is shown and in particular a comprehensive seal is provided with rings  72 ,  73 ,  75  and  76  which register within corresponding grooves  71  formed within the valving block  78  circumjacent respective inlet and outlet ports, as well as at the inner and outer peripheries thereof. Although not shown the grooves  71  are typically provided within their bases with wave or undulated spring blades to ensure appropriate pressure is applied to create an adequate and effective seal as between the valving block  78  and head  27 . Further, although not required, there can be seen from the illustration in  FIG. 13  that the seals are provided with cuts that permit efficient sealing within the grooves  71  of the block  78 . It will be appreciated that during use it is the ring seals that will contact the machined surface of the head  27 . From  FIG. 14  it will be observed that the seal rings  72 ,  73 ,  75  and  76  are eccentric in relation to the cylinder head  27  thus ensuring that the aperture  28  in the head  27  will always be surrounded during rotation and that the seal rings will not always contact the same area in the cylinder head  27 . 
     In operation, the rotary engine  1  of the present invention would be coupled to a load of some description requiring rotational power. A fuel supply would be coupled to the valving block  78  via an appropriate fuel distributor, e.g. a carburettor, and a spark igniter (not shown) is provided for giving the requisite initiation for ignition to occur thereby to drive the piston  50  longitudinally within the cylinder  26 . In so doing the crankshafts  70  and  80  are caused to rotate synchronously in opposite directions by the thrust of the piston on the connecting rods  48  and  49 . The rotation of the crankshafts  70  and  80  triggers rotation of the bevel gears  10 ,  12 , which contra-rotate, and through the meshing engagement with the static bevel gear ring  88  the piston  50  and the cylinder  26  together with the other moving parts rotate about the cylinder axis (not shown) and in so doing the gear cage cradle  29  and the gear cage base  32  rotate the output shaft  30  to transmit drive to the working load (not shown). The contra-rotation of the connecting rods  48 ,  49  provides a balanced power transmission which minimises vibration and thus noise generation. All components illustrated in  FIGS. 4 ,  5  and  16  do rotate about the cylinder axis during operation of the engine  1 ; and similarly for the embodiment of  FIGS. 6 and 17 . Accordingly, fuel economy is an advantage to be gained by the inventive configuration disclosed herein. 
     In an other embodiment (not shown), the seal rings  72 ,  73 ,  75  and  76  could be replaced by a single seal ring that would be in register with a corresponding groove surrounding the head aperture  28  and be in sealing contact with a machined surface of the valving block  28 . In such an embodiment, there is less parts and only the valving block  28  gets replaced when worn out by the sealing ring, instead of the cylinder head  27 . 
     It is to be understood that other configurations could be adopted whereby more than a single cylinder would be provided; however the balanced loading achieved with the single cylinder should be maintained. Since the engine is essentially modular, a series of these modules could be assembled in a suitable array to provide the power required in any given circumstance. 
     While a specific embodiment of the rotary engine of the present invention has been described, those skilled in the art will recognize many alterations that could be made within the spirit of the invention. The description provided herein is provided only for purposes of illustration, and not for purposes of limitation.