AU8003898A

AU8003898A - Rotary cylinder radial piston engine

Info

Publication number: AU8003898A
Application number: AU80038/98A
Authority: AU
Inventors: Colin A. Clifford
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-06-12
Filing date: 1998-06-12
Publication date: 1998-12-30
Also published as: WO1998057036A1

Description

WO 98/57036 PCT/AU98/00456 ROTARY CYLINDER RADIAL PISTON ENGINE -- BACKGROUND OF THE INVENTION- This invention relates to radial engines. This invention has particular but not exclusive 5 application to spark ignition engines, and for illustrative purposes particular reference will be made to such application. However, it is to be understood that this invention could be used in other applications, such as fluid compressors or pumps which are embraced hereinafter by the 10 term "engine". In my earlier International Patent Application No. PCT/AU93/00108 I describe a radial type engine assembly having a crankcase assembly supporting a crankshaft assembly and a cylinder assembly for rotation about the crankshaft, 15 the cylinder assembly having a uneven number of symmetrically disposed radial cylinders and receiving pistons reciprocated by the crankshaft assembly. A ported cylinder closure is mounted to the crankcase with port timings being controlled by passage of the open outer ends of the cylinders therepast. 20 The cylinder assembly is adapted to contra-rotate at a reduced speed compared to the crankshaft at a reduction ratio equal to one divided by the number of cylinders in the or each bank of cylinders, and the port numbers being selected for two or four stroke operation. For this purpose the inlet 25 and outlet ports are grouped in pairs of circumferentially spaced inlet and exhaust ports and the number of pairs of circumferentially spaced pairs of inlet and exhaust ports being equal to [2 + s] x [ 1 + n] where s = the number of piston strokes per cyclic 30 induction, compression, expansion, and exhaust process, and n = the number of cylinders. Such engines will be referred to hereinafter as "the type described". 35 --SUMMARY OF THE INVENTION- The present invention aims to provide improvements to the two and four stroke engines of the type described. With the foregoing in view, this invention resides WO98/57036 PCT/AU98/00456 2 broadly in an engine assembly of the type described wherein the inner surface of said cylinder closure means about said cylinder assembly is a part-spherical surface and the outer surface surrounding each said cylinder lies in a common part 5 spherical plane operatively conforming to said part spherical surface and wherein each said outer surface surrounding respective said cylinders supports radially spaced ring type seals which form a sliding seal between said outer surface surrounding each said cylinder and said part 10 spherical surface. Preferably the ring type seals are split ring type seals. Suitably the ring type seals are metal seals. It one preferred form the engine assembly is configured as a spark ignition combustion engine having spark plug 15 recesses in the cylinder closure which open to the cylinders to fully expose the spark plugs to the cylinders and wherein the radially spaced ring type seals are spaced so that they straddle the spark plug cylinder openings as they pass thereacross. 20 In this arrangement substantially unrestricted access to the cylinders for admission of air/fuel mixture to the spark plugs contained therein is provided ensuring effective ignition and conditioning of the spark plug, one of the prime requirements for maximum performance operation while the 25 radial spacing of the ring type seals prevents the formation of a gas bleed path as occurs with a single ring type seal when it is disposed across the spark plug opening, the gas being able to travel up and over the seal through the plug recess. 30 In yet another aspect this invention resides broadly in an engine assembly including: a crankcase assembly; a crankshaft assembly supported by said crankcase assembly; 35 a cylinder assembly rotatable relative to said crankcase assembly about said crankshaft assembly, said cylinder assembly having an uneven number of cylinders disposed radially about the crankshaft assembly and with their axes WO98/57036 PCT/AU98/00456 3 co-planar; respective piston assemblies connected to said crankshaft assembly for operation within said cylinders; cylinder closure means supported fixedly by said 5 crankcase assembly for closing said cylinders and having an operatively continuous inner closure surface sealably and slidably engaged with the cylinders; inlet and outlet ports through said inner closure surface through which fluid may be cyclically introduced into 10 or expelled from said cylinders, the inlet and outlet ports being grouped in pairs of circumferentially spaced inlet and exhaust ports, and said engine assembly is a spark ignition internal combustion engine and the spark plug apertures in which the 15 respective spark plugs are mounted extend through the cylinder closure means such that the open ends of the spark plugs open fully to the cylinders. Preferably the outer surface surrounding respective said cylinders supports a pair of concentrically spaced apart ring 20 type seals which form a sliding seal between said outer surface surrounding each said cylinder and said part spherical surface. Most preferably the spacing between each pair of ring type seals is greater than the diameter of said spark plug recesses. 25 It is also preferred that the ring type seals are supported in respective recesses having a depth greater than the height of the ring type seal accommodated therein. The ring type seals are biased by rotational forces into operative engagement with the spherical cylinder closure 30 surface however it is preferred that at least one of said ring seals about each cylinder includes a base spring which engages the base of its accommodating recess and urges the ring type seal outwardly beyond its accommodating recess. This arrangement will assist in sealing, particularly during 35 start-up when good compression from cold is required at very low revs. In yet another aspect this invention resides in an engine assembly including:- WO98/57036 PCT/AU98/00456 4 a crankcase assembly; a crankshaft assembly supported by said crankcase assembly; a cylinder assembly rotatable relative to said crankcase 5 assembly about said crankshaft assembly, said cylinder assembly having an uneven number of cylinders disposed radially about the crankshaft assembly and with their axes co-planar; respective piston assemblies connected to said 10 crankshaft assembly for operation within said cylinders; cylinder closure means supported fixedly by said crankcase assembly for closing said cylinders and having an operatively continuous inner closure surface sealably and slidably engaged with the cylinders; 15 inlet and outlet ports through said inner closure surface through which fluid may be cyclically introduced into or expelled from said cylinders, the inlet and outlet ports being grouped in pairs of circumferentially spaced inlet and exhaust ports, and wherein 20 said exhaust ports are angled from the radial direction in the direction of rotation of the cylinder assembly. The exhaust ports suitably diverge at an angle of between thirty and sixty degrees from the radial direction and more preferably at about forty-five degrees from the 25 radial direction. The exhaust port may emerge from the cylinder closure means from the outer surface thereof but preferably the exhausts ports emerge through a common or respective side wall portion of the cylinder closure means. The exhaust port and the inlet ports may both emerge 30 from the side wall portions of the cylinder closure means and suitably at respective opposite sides thereof. It is also preferred that the ports emerge such that the inlet and exhaust pipes or ducts may extend cleanly therefrom in a circumferential or tangential direction so that they may be 35 accommodated close to the engine. The inlet ports include a substantially centrally disposed primary port utilised for low speed operation and a secondary port disposed at one side of said primary port and WO98/57036 PCT/AU98/00456 5 opened for high speed operation and wherein the exhaust tract in said cylinder closure means between its opening to the cylinder and its opening through said side wall portion extends past said primary port at the opposite side thereof 5 to said secondary port. Preferably the engines of this invention are of the type described but this invention is not limited to engines as devised by the present inventor and may be advantageously used in other similar engines as listed in the prior art 10 statement of my US patent No. 5,524,577. --BRIEF DESCRIPTION OF THE DRAWINGS- In order that this invention may be more readily understood and put into practical effect reference will now be made to the accompanying drawings which illustrate typical 15 embodiments of the present invention and wherein: FIG. 1 is a diagrammatic end view of an embodiment of a five cylinder four-stroke radial engine according to the present invention; FIG. 1A is a partial sectional view of the part of the 20 embodiment of Fig. 1 further illustrating the inlet port configuration; FIG. lB is a diagrammatic illustration of the inlet ports of the embodiment of Fig. 1; FIG. 2 is a diagrammatic transverse sectional view 25 through the engine illustrated in FIG. 1; FIG. 3 is an enlarged end view showing details of the cylinder sealing and spark plug arrangement; FIG. 4 is an enlarged diagrammatic transverse sectional view taken along the line 4-4 of Fig. 14; 30 FIG. 5 illustrates further details of a preferred form of cylinder sealing; FIGS. 6, 6A and 6B correspond to Figs. 1 but illustrate a central secondary inlet port; FIG. 7, 7A and 7B correspond to Figs. 6 but illustrate a 35 relatively short central primary inlet port; FIG. 8, 8A and 8B correspond to Figs. 6 but illustrate an exhaust port crossing the inlet ports; FIG. 9, 9A and 9B correspond to Figs. 6 but illustrate a WO98/57036 PCT/AU98/00456 6 an arrangement wherein the ports exit from opposite sides of the cylinder closure means. -DESCRIPTION OF THE PREFERRED EMBODIMENT- In the engine 10 illustrated in Figs. 1 to 5, the open 5 inner end of the spark plug recesses 11 fully expose the spark plugs 12 to the cylinders and sealing between the rotary cylinder assembly 13 and the cylinder closure assembly 14 about each cylinder 15 is achieved by the use of at least two radially spaced split-ring type seals 16 located in ring 10 grooves 17. In order to prevent the spark plugs from extending beyond the spherical surface 19 of the cylinder closure assembly 14 the recesses 11 are longer than the screw-in portions of the spark plugs as any protrusion beyond this 15 surface would trap the ring seals 16. Thus the respective openings to the cylinder surface correspond to the width of the recesses 11. The radially spaced split-ring type seals 16 are spaced apart a distance greater than the outside diameter of the 20 plug recesses 11 so that the recesses 11 are only exposed to one seals 16 at a time and thus preventing the plug recess acting as a bypass passage across the ring seals 16. For this purpose the rotary cylinder assembly 13 has an axial length at its interface with the cylinder closure 25 assembly 14 whereby lands are formed around the cylinders of sufficient width to accommodate the concentrically disposed widely spaced seals 16. If desired one or more further concentric split-ring type seals could be provided between the widely spaced seals 16. This arrangement is clearly 30 illustrated in Figs. 3 and 4. Referring to Fig. 5 it will be seen that each split-ring type seal 16 is located in a respective groove 17 and is resiliently urged beyond the open end thereof by a coarsely coiled spring 18. A wavey flat spring may be equally used. 35 For example in a recess having a radius of two and one half inches, a depth of one-eight inch and a width of one sixteenth inch, the coil spring could be formed of thin spring steel wire of about ten thousandth of an inch diameter WO98/57036 PCT/AU98/00456 7 and having four coils in its length which is approximately equal to the circumference of the recess. Furthermore the depth D of the recess is greater than the combined diameter # of the steel wire plus the height H 5 of the seal 16. This ensures that in an overheating situation if the rotary cylinder assembly 13 expands in diameter to form an interference fit in the closure assembly 14, the seals 16 will be able to retract fully into the ring groove 17. 10 The inlet ports comprise a central short primary port 26 controlled by the butterfly valve 27 and outer long secondary ports 28 controlled by the butterfly valve 29. The exhaust ports 20 are angled from the radial direction in the direction of rotation of the rotary cylinder 15 assembly 13 and suitably the exhaust ports 20 diverge at about forty-five degrees from the radial direction. This configuration aims to take advantage of the radial component of motion of the exhaust gases relative to the cylinder axis, wherein at the interface between the cylinder closure 20 assembly 14 and the rotary cylinder assembly 13, the tangential speed imparted to combustion gases by rotation of the rotary cylinder assembly 13 is greater than the radial speed imparted thereto by the reciprocating pistons. It will also be seen that the outer edge 21 of the 25 rotary cylinder assembly 13 is recessed to provide a sealing land 22 for conventional lip-type seals 23 retained in the cylinder closure assembly 14. This recess also provides a location shoulder 24 terminating the part spherical shape of the outer surface 25. Peripheral radial engagement sealing 30 of the cylinder is preferred so that oil clearances on bearing surfaces, which may result in a slight wobbling of the rotating cylinder do not cause cyclic distortion of the lip-type seals 23 such that they will become inoperative or significantly increase their frictional restraint on the free 35 rotation of the cylinder assembly. In the embodiment illustrated in Figs. 6 the secondary port 30 is centrally disposed and is much longer than the primary ports 31. This enables the number of butterfly WO98/57036 PCT/AU98/00456 8 valves to be limited to two, comprising a single central valve 33 for the secondary port and a further single butterfly valve 34 controlling the primary inlet as well as the flow to the secondary port. 5 The embodiment illustrated in Figs. 7 is similar to the embodiment illustrated in Fig. 1. It has the advantage that as the secondary ports 40, together with their butterfly valve 41 and the primary port 42 are supplied from a common tract 43 controlled by a butterfly valve 44. Thus a single 10 fuel injector in the tract 43 will supply all ports, whereas the Fig. 1 embodiment would be more suited to a dual-throat carburetor mounted above the primary and secondary butterflies 27 and 29 supported in the inlet manifold 36 adjacent its entrance 37. 15 Figs. 8 also illustrate inlet manifolds 50 and exhaust manifolds 51 mounted on the periphery of the cylinder closure 52. However, in this embodiment the inlet ports comprise a short primary port 53 to one side of the cylinders 54 and a large long secondary port 55 at the other side of the 20 cylinders. Both the inlet ports 53 and 55 deflect to one side of the engine axis to provide room for the adjacent exhaust manifold portion 56 to pass with minimum deflection in the exhaust passage while maintaining a compact overall 25 configuration. Butterfly valves 55 and 56 control the primary and secondary ports respectively. In the embodiment illustrated in Fig. 9 the inlet ports 60 and the exhaust ports 61 are cast integrally into the cylinder closure assembly whereby they exit from respective 30 opposite side faces 62 and 63 of the cylinder closure assembly 64. This enables the inlet and outlet manifolds to be maintained within the boundary surrounding the cylinder closure assembly 64 where required to suit installation space requirements. The cast in manifolds should also simplify 35 manufacture. Furthermore it will be seen that the exhaust port 65 has a narrow leading portion 66 which extends to a substantially rectangular main part 67. This arrangement enables a initial WO98/57036 PCT/AU98/00456 9 exhaust flow to commence from the cylinders 68 through the exhaust port without providing the sudden pressure loss provided by a simple rectangular port. It is considered that this will benefit low speed performance. 5 Concave piston crowns are retained because of the ease of varying the compression ratio by changing pistons only and to act synergistically with a substantial centrally disposed inlet port. It is considered that as the concave piston passes across the inlet ports, the relative tangential 10 movement imparts a swirling action generated about an axis parallel to the crankshaft axis and in a direction which enhances exhausting through the angled exhaust ports. If desired a single substantially centrally disposed inlet port may be used, however it is preferred that the 15 inlet ports have a central port and at least one offset port. The substantially centrally disposed inlet ports and the offset ports suitably provide independent primary and secondary feeds to the cylinders. In all cases it will be appreciated that the engines of 20 the present invention have fewer moving and stationary parts than conventional engines while at the same time providing unimpeded ports and the like which should enable the engines to rev to a relatively high speed or operate efficiently at low speeds. Thus, depending on the application, each 25 cylinder may communicate with a single inlet port or multiple inlet ports which may serve only to increase the port area or to provide differences in communication duration on each pass. Furthermore all manufacturing functions of the present 30 invention are relatively straight forward using existing technology. Of course if desired ceramic or other non metallic components can be used in selected applications to further enhance the performance of engines made in accordance with the present invention. 35 From the above it will be seen that engines made in accordance with this invention will have a short crankshaft which may be relatively light and stiff. Manufacturing techniques and components are relatively simple, utilizing WO98/57036 PCT/AU98/00456 10 circular shape seals throughout the engine. The engines have relatively few moving parts and power strokes overlap to enable smooth operation to be provided. If desired the engine may be designed for operation on petroleum, diesel, 5 kerosene or natural gas or the like. It will of course be realised that the above has been given only by way of illustrative example of the invention and that all such modifications and variations thereto as would be apparent to persons skilled in the art are deemed to 10 fall within the broad scope and ambit of the invention as is defined in the appended claims.

Claims

1. An engine assembly of the type described wherein the inner surface of said cylinder closure means about said cylinder assembly is a part-spherical surface and the outer 5 surface surrounding each said cylinder lies in a common part spherical plane operatively conforming to said part-spherical surface and wherein each said outer surface surrounding respective said cylinders supports radially spaced split-ring type seals which form a sliding seal between said outer 10 surface surrounding each said cylinder and said part spherical surface.

2. An engine assembly including: a crankcase assembly; a crankshaft assembly supported by said crankcase 15 assembly; a cylinder assembly rotatable relative to said crankcase assembly about said crankshaft assembly, said cylinder assembly having an uneven number of cylinders disposed radially about the crankshaft assembly and with their axes 20 co-planar; respective piston assemblies connected to said crankshaft assembly for operation within said cylinders; cylinder closure means supported fixedly by said crankcase assembly for closing said cylinders and having an 25 operatively continuous inner closure surface sealably and slidably engaged with the cylinders; inlet and outlet ports through said inner closure surface through which fluid may be cyclically introduced into or expelled from said cylinders, the inlet and outlet ports 30 being grouped in pairs of circumferentially spaced inlet and exhaust ports, and said engine assembly is a spark ignition internal combustion engine and the spark plug apertures in which the respective spark plugs are mounted extend through the 35 cylinder closure means such that the open ends of the spark WO98/57036 PCT/AU98/00456 12 plugs open fully to the cylinders.

3. An engine assembly as claimed in claim 1 or claim 2, wherein each said outer surface surrounding respective said cylinders supports a pair of concentrically spaced apart ring 5 type seals which form a sliding seal between said outer surface surrounding each said cylinder and said part spherical surface.

4. An engine assembly as claimed in claim 3, wherein each said ring seal is a split-ring type seal. 10

5. An engine assembly as claimed in claim 3 or 4, wherein the spacing between said ring seals is greater than the diameter of said spark plug recesses.

6. An engine assembly as claimed in any one of the preceding claims, wherein said ring type seals are supported in 15 respective recesses having a depth greater than the height of the ring type seal accommodated therein.

7. An engine assembly as claimed in claim 6, wherein at least one of said ring type seals about each cylinder includes a base spring which engages the base of its accommodating 20 recess and urges the ring type seal outwardly beyond its accommodating recess.

8. An engine assembly including: a crankcase assembly; a crankshaft assembly supported by said crankcase 25 assembly; a cylinder assembly rotatable relative to said crankcase assembly about said crankshaft assembly, said cylinder assembly having an uneven number of cylinders disposed radially about the crankshaft assembly and with their axes 30 co-planar; respective piston assemblies connected to said crankshaft assembly for operation within said cylinders; WO98/57036 PCT/AU98/00456 13 cylinder closure means supported fixedly by said crankcase assembly for closing said cylinders and having an operatively continuous inner closure surface sealably and slidably engaged with the cylinders; 5 inlet and outlet ports through said inner closure surface through which fluid may be cyclically introduced into or expelled from said cylinders, the inlet and outlet ports being grouped in pairs of circumferentially spaced inlet and exhaust ports, and wherein 10 said exhaust ports are angled from the radial direction in the direction of rotation of the cylinder assembly.

9. An engine assembly as claimed in claim 8, wherein said exhaust ports diverge at an angle of between thirty and sixty degrees from the radial direction. 15

10. An engine assembly as claimed in claim 9, wherein said exhaust ports diverge at an angle of about forty-five degrees from the radial direction.

11. An engine assembly as claimed in any one of claims 8 to 10, wherein said exhaust emerge through a side wall portion 20 of the cylinder closure means.

12. An engine assembly as claimed in claim 11, wherein said inlet ports include a substantially centrally disposed primary port utilised for low speed operation and a secondary port disposed at one side of said primary port and opened for 25 high speed operation and wherein the exhaust tract in said cylinder closure means between its opening to the cylinder and its opening through said side wall portion extends past said primary port at the opposite side thereof to said secondary port.