ROTARY INTERNAL COMBUSTION ENGINE

Abstract: A rotary internal combustion engine including a housing (10); a first vane (34a,34b) mounted for rotation in the housing on a fixed axis; a second vane (36a,36b) mounted for rotation in the housing on the fixed axis independently of the first vane; a separate ratchet mechanism respectively engaging the first and second vanes to preclude rotation of the vanes in one direction about the axis while allowing free rotation in the other direction; and a converter mechanism, including an output shaft, drivingly connected to the vanes and operative to convert the rotation of the vanes into a unidirectional, constant speed rotation of the output shaft of the converter means. In one disclosed embodiment, the converter means comprises a differential gear assembly in which the vanes are coupled to different pinions in a differential gear assembly and the pinions coact in known differential gear manner to rotate the output shaft of the differential gear assembly in a unidirectional, constant speed manner. In other disclosed embodiments, the converter means comprises a pneumatic coupling, a hydraulic coupling, and a hydraulic differential coupling.

Description: The invention relates to a rotary internal combustion engine according to the preamble of claim 1 and to a method of starting said engine according to the preamble of claim 7. A multitude of designs have been proposed for rotary internal combustion engines over the years and yet, despite the multiplicity of such rotary designs, and despite the obvious advantages of unidirectional movement inherent in the rotary design, the reciprocating variety of engine continues to account for the vast majority of internal combustion engines sold. This presumably is because the various rotary designs proposed have either been too complex to manufacture on a large scale, have been inefficient in operation, have required an inordinate amount of maintenance, or have had a relatively short product life. This invention relates to a rotary internal combustion engine of the type in which two rotating pistons or vanes are connected to concentric shafts or hubs with the leading and following pistons rotating in a manner that allows the pistons to alternately approach and move away from each other to permit the intake of a combusible fuel mixture, its compression, ignition, expansion and exhaust. Prior art rotary internal combustion engines of this type have suffered from an inability to convert the somewhat promiscuous and seemingly random movement of the two pistons into a predictable, usable movement of an output shaft. Prior art attempts to provide a predictable or usable movement of the output shaft have involved the attempted use of a predetermined program to control the compression and expansion strokes wherein a fixed program of motion between the pistons is established by the use of cams, lobes, planetary gears, cranks, grooves, slots, rollers and/or other similar linkages. However, these prior art attempts to provide a predictable, usable movement of the output shaft by providing a predetermined fixed program of motion between the pistons have been unsuccessful since they have generated uncompensated stresses which have tended to literally tear the engine apart. They have also resulted in engine designs that are unduly complex, unduly expensive to manufacture, and which require an inordinate amount of maintenance. A rotary internal combustion engine as mentioned in the preamble of claim 1 is mentioned in GB-A 619,995. This internal combustion engine is designed to work on the two-stroke principle, preferably with scavenging by air flowing in one direction and admitted through ports. Said engine comprises exhaust and scavenging openings, wherein the latter may be of greater height than said exhaust openings in order to prolong the air admission, and may be fitted with valves to prevent the escape of the burnt gases. The scavenging air is supplied by a compessor. It is an object of the invention to provide a rotary internal combustion engine such that a relative motion of the pistons can be achieved in order to facilitate starting of the engine and the method for operating said engine. This object is achieved by a rotary internal combustion engine comprising the features of claim 1 and by a method comprising the features of claim 7. Further embodiments of the invention are disclosed in the subclaims. This invention is directed to the provision of an improved rotary internal combustion engine of the rotary piston type. The invention engine includes a housing; a first piston or vane mounted for rotation in the housing on a fixed axis; a second piston or vane mounted for rotation in the housing on the fixed axis independently of the first vane; means precluding rotation of either vane in one direction about the axis while allowing free rotation in the other direction about the axis so that the vanes may rotate freely in the other direction and may simultaneously undergo relative rotation; and converter means, including an output shaft, drivingly connected to the vanes and operative to convert the rotation of the vanes in such other direction as well as the relative rotation of the vanes into a unidirectional, steady speed rotation of the output shaft of the converter means. The rotary vanes are mounted on concentric shafts and the concentric shafts in turn are drivingly connected to separate elements of the converter means. The separate elements in the converter means operate to drive the output shaft of the converter means at a uniform, constant speed. The concentric shafts of the two rotary vanes are precluded from rotation in the opposite direction by ratchet means which respectively coact with each of the concentric shafts. In one embodiment of the invention, the converter means comprises a differential gear assembly in which the concentric shafts, which are rotating in the same direction but at different speeds, are coupled to different pinions in the differential gear assembly and the pinions coact in known differential gear manner to rotate the output shaft of the differential gear assembly in a unidirectional, constant speed manner. According to another embodiment of the invention, the converter means may comprise a pneumatic coupling which is comprised of vanes which move in the same pattern as the vanes of the engine. According to a further embodiment, the converter means may comprise a hydraulic coupling, and according to a still further embodiment, the converter means may comprise a hydraulic differential coupling. Brief Description of the Drawings FIGURE 1 is a schematic, longitudinal cross-sectional view of the invention engine; FIGURE 2 is a tranverse cross-sectional view taken on lines 2-2 of FIGURE 1; FIGURE 3 is perspective view of the piston vane assembly used in the engine of FIGURE 1; FIGURE 4 is a cross-sectional view of the converter means shown in the engine of FIGURE 1; FIGURE 5 is a transverse cross-sectional view taken on lines 5-5 of FIGURE 1; FIGURE 6 is view of an alternate form of converter means for use in the engine of FIGURE 1; FIGURE 7 is a cross-sectional view taken on line 7-7 of FIGURE 6; FIGURE 8 is a view of another alternate form of converter means for use in the engine of FIGURE 1; FIGURE 9 is a cross-sectional view taken on line 9-9 of FIGURE 8; FIGURE 10 is a view of a still further alternate converter means for use in the engine of FIGURE 1; and FIGURE 11 is a cross-sectional view taken on line 11-11 of FIGURE 10. Detailed Description of the Preferred Embodiment The rotary internal combustion engine seen in schematically and in longitudinal cross section in Figure 1, broadly considered, includes a housing 10; a rotary piston assembly 12; a ratchet assembly 14; and a converter mechanism 16. Housing 10 is cylindrical and defines a cylindrical combustion chamber 18. A sparkplug or glow plug 20 is provided at a top dead center location in the housing and communicates with combustion chamber 18, and intake and exhaust ports 22 and 24 are provided adjacent the lower end of the housing generally opposite plug 20. For example, the intake and exhaust ports may be located on opposite sides of, and approximately twenty degrees from, the bottom dead center or six o'clock position on the housing. Fins 10a are provided for cooling housing 10. Rotary piston assembly 12 is positioned within housing 10 and includes a first shaft or hub 26 including axially spaced separate portions 26a and 26b; a pair of bearings 28 and 30 positioned in opposite side walls of housing 10 and respectively journalling shaft portions 26a and 26b; a shaft or hub 32 concentric with shaft 26 and journalled within shaft 26; a first rotary vane or piston 34 secured to shaft portions 26a and 26b, and a second vane or piston 36 secured to shaft 32. Vane 34 includes first and second portions 34a and 34b. Portion 34a is secured to shaft portion 26a along inner vane edge 34c and is secured to shaft portion 26b at 34d with an intermediate inner vane edge portion 34e closely but slideably interfacing with shaft 32. Vane portion 34b is secured to shaft portion 26a along inner vane edge 34f and is secured to shaft portion 26b at 34g with an intermediate vane edge portion 34h closely but slideably interfacing with shaft 32. Vane 36 includes first and second portions 36a and 36b. Vane portion 36a is secured to shaft 32 along inner vane edge 36c and closely but slideably interfaces with shaft portion 26a at 36d and with shaft portion 26b at 36e. Vane portion 36b is similarly mounted and disposed with respect to shaft 32 and shaft portions 26a and 36b. Vanes or pistons 34 and 36 are configured to fit as tightly as possible within the combustion chamber without actually touching the walls of the chamber as they rotate relative to the chamber. If desired, an internal lubricant or oil may be used to protect the edges of the pistons and the adjacent walls of the chamber although, with proper control of the fit between the pistons and the walls of the combustion chamber, an internal lubricant may not be necessary. As seen, the pistons have a generally wedge shaped configuration. Although other piston shapes may be used, the disclosed wedge shape is desirable because, as the pistons approach each other during their relative rotation within the combustion chamber, their faces move into a parallel relationship to minimize the danger of any protrusions on the faces of either piston coming into contact with the adjacent piston. Ratchet assembly 14, as best seem in FIGURES 1 and 5, includes a pair of ratchet mechanisms 38 and 40 respectively associated with each of the concentric shafts 26 and 32. Ratchet mechanisms 38 and 40 are disposed side-by-side in axially spaced relation in a circular housing 42. Housing 42 includes an end wall 42a upstanding from a suitable support surface 43 and supporting bearing 30 and thereby one end of housing 10. The other end of housing 10 is supported by a support plate 44 upstanding from surface 43 and supporting bearing 28. Each ratchet mechanism includes a circular ratchet body 45 secured to the respective shaft and a plurality of balls 46 respectively ensconced in a plurality of circumferentially spaced pockets 48 provided on the periphery of ratchet body 45. Ratchet body 45 and balls 46 coact in known manner with housing 42 to preclude counterclockwise rotation of the respective shaft as viewed in Figure 5 while allowing free clockwise rotation of the respective shaft. Converter mechanism 16, as best seen in Figure 4, includes a housing 50, an output shaft 52 fixedly and centrally secured to housing 50, and a plurality of pinion bevel gears 54, 56, 58 and 60 positioned within housing 50. Pinion gear 54 is drivingly secured to shaft 32; pinion gear 56 is drivingly secured to shaft portion 26a; and pinion gears 58 and 60 are meshingly engaged with gears 54 and 56 and secured in axially spaced relation on a pinion shaft 62 which in turn is journalled at its upper and lower ends in journal portions 50a and 50b of housing 50. The engine further includes a supercharger 64 including a blower 66 drivingly connected to output shaft 52 of converter mechanism 16 by reduction gears 68, 70, 72 and 74. A suitable conduit 76 interconnects the output of supercharger 64 with the intake port 22 of housing 10. OPERATION To start the engine, an electric motor (not shown) rotates the output shaft 52 to impart initial rotation to pistons 34, 36. In order to impart differential rotation as well as absolute rotation to the pistons, supercharger 64 operates to supply a stream or charge of pressurized gas to the intake 22. This charge begins the compression and expansion strokes of the engine. Instead of a supercharger, a turbocharger, tank of compressed air, blower or other suitable means for supplying gas can be used. For the sake of simplicity, a carburetor or other fuel mixing device is not shown in the drawings. The movement of the pistons 34, 36 through the various phases of the engine operation is best seen in Figure 2. With the pistons 34 and 36 in the position seen in Figure 2, the sparkplug 20 is energized to ignite the fuel mixture confined by piston portions 34a and 36a. As the fuel burns and expands, it acts against piston portion 36a to force piston 36 to rotate in a clockwise direction. The piston 34 is prevented from counterclockwise rotation by ratchet mechanism 38. As piston portion 36a approaches piston portion 34b, burned combustion products from the previous ignition are expelled through exhaust port 24. At the same time, a new fuel air mixture is drawn in through intake port 22 as piston portion 36b separates from piston portion 34b, and the charge confined in the area between piston 36b and piston portion 34a is compressed. As piston portion 36b moves close to piston portion 34a, the build-up of pressure in the space between the two piston portions forces piston portion 34a to move past sparkplug 20 and a new charge is ready for firing to complete the cycle. Just before the sparkplug ignites the new charge, both pistons 34 and 36 are moving in a clockwise direction. After the firing, the relative rates at which piston 34 decelerates and piston 36 accelerates can be determined by the following analysis: Let: F equal the clockwise force on a pair of pistons A equal the area on one side of a piston T equal time S equal speed Then: 1. F₃₄ = -AP 36a-34a + AP 34a-36b - AP 36b-34b + AP 34b-36a 2. F₃₆ = AP 36a-34a - AP 34b-36a - AP 34a-36b + AP 36b-34b 3. F₃₄ = -F₃₆ Assuming the mass of the concentric shafts are the same and the two pistons are equal in size, from F = mass x acceleration = mass x Δ S 4. ΔS₃₄ = -ΔS₃₆ or ΔS₂₆ = -ΔS₃₂ From the geometry of a differential gear coupling 5. 1/2S₂₆ + 1/2S₃₂ = S₅₂ where S₂₆, S₃₂ and S₅₂ are the respective speeds of concentric shaft 26, concentric shaft 32, and output shaft 52. After a lapse of time equal to Δ T: 6. 1/2 (S₂₆ + ΔS₂₆) + 1/2 (S₃₂ + ΔS₃₂) = S₅₂ + ΔS₅₂ or 7. 1/2ΔS₂₆ + 1/2ΔS₃₂ = ΔS₅₂ by substituting equation 4. in equation 7. 8. ΔS₅₂ = 0 Thus, for a given engine throttle setting, the output speed of the drive shaft 52 is constant as the pistons 34 and 36 alternately accelerate and decelerate during the engine cycle. When a particular piston is held stationary by its ratchet mechanism, the speed of the drive shaft 52 equals 1/2 of the speed of the other or moving piston. Although a differential gear assembly is eminently satisfactory for use with the invention rotary internal combustion engine, other converter mechanisms may be used. For example, as seen in Figures 6 and 7, a pneumatic coupling 78 may be used as the converter mechanism. Coupling 78 includes a housing 80 and vanes 82 and 84. Housing 80 is generally circular and defines a central chamber 86 within which vanes 82 and 84 are disposed. Output shaft 52 is defined centrally and integrally with one side wall 80a of the housing and four internal vanes 88 are provided integral with the housing and projecting radially inwardly from the outer shell of the housing. Shafts 32 and 26a are suitably journalled in side walls 80a and 80b of the housing. Vane 82 includes vane portions 90 and 92 secured to shaft 26a in a manner similar to the securement of piston 34 to shaft 26a. Vane 84 includes vane portions 94 and 96 secured to shaft 32 in a manner similar to the securement of piston 36 to shaft 32. A compressible gas is contained within the housing. Housing vanes 88 will move so as to remain equidistant between vanes 82 and 84. This behavior assumes that the vanes fit airtight and that the inertia in the output shaft can be ignored. The above relationship can be expressed mathematically as follows: Let ϑ equal the location of a vane. Then: 1. ϑ₉₄ - ϑ₈₈ = ϑ₈₈ - ϑ₉₀ After a time lapse of Δ T, vane 94 will be at ϑ₉₄ + Δ ϑ₉₄; vane 90 will be at ϑ₉ 0 + Δϑ ₉₀; and housing vane 88 will be at ϑ₈₈+ Δϑ₈₈ so that: 2. ϑ₉₄ + Δϑ₉₄ - ϑ₈₈ - Δϑ₈₈ = ϑ₈₈ + Δϑ₈₈ - ϑ₉₀ - Δϑ₉₀ By combining equations 1 and 2: 3. Δϑ₉₄ - Δϑ₈₈ = Δϑ₈₈ - Δϑ₉₀ or 4. Δϑ₉₄ + Δϑ₉₀ = 2Δϑ₈₈ Dividing equation 4 by 2 T, the following expression is obtained: 5. 1/2S₉₄ + 1/2S₉₀ = S₈₈ This equation will be recognized as the same as the equation describing the motion of the differential gear coupling 16. Thus, for the purposes of this invention, the differential gear coupling 16 and the pneumatic coupling 78 perform identically and may be used interchangeably. Other types of converter mechanisms may also be employed. Thus, referring to Figures 8 and 9, a hydraulic coupling 190 may also be employed as the converter mechanism. Coupling 190 includes a housing 192 and a pair of vanes 194 and 196. Housing 190 has a multi-lobe configuration in cross section and includes a series of circumferentially spaced internal vanes 198 extending radially inwardly from the outer shell of the housing. Vanes 194 and 196 are secured, to shafts 26a and 32 in the same manner described previously with reference to the securement of vanes 34 and 36 to shafts 26a and 32. The lobed configuration of the casing has the effect of reducing fluid friction while still preventing the moving vanes 194 and 196 from colliding with the housing vanes 198. A further form of converter mechanism is seen in Figures 10 and 11. The converter mechanism of Figures 10 and 11 comprises a hydraulic differential coupling 99. Coupling 99 includes a housing 100; a first gear set 102; and a second gear set 104. Housing 100 is generally cylindrical and defines an inner chamber 106 within which gear sets 102 and 104 are disposed. Gear set 102 is associated with shaft 32 and includes a sun gear 108 keyed to shaft 32; a pair of planetary gears 110 and 112 meshingly engaging with diametrically opposed portions of sun gear 108 and journalled in chamber 106 by shafts 114 and 116; and a further pair of planetary gears 118,120 meshingly engaging respectively with planetary gears 110 and 112 and journalled in chamber 106 by shafts 122 and 124. Similarly, gear set 104 includes a sun gear 126 keyed to shaft 26a; a pair of planetary gears 128 and 130 meshing with diametrically opposed portions of sun gear 126 and journalled in chamber 106 on shafts 114 and 116; and a further pair of planetary gears (not shown) meshingly engaging respectively with planetary gears 128 and 130 and carried on shafts 122 and 124, respectively. The four planetary gears that are associated with each sun gear rotate tangentially to the inner wall of the housing 100 and they therefore act as a gear pump. Because these gears oppose each other, they are kept from rotating about their axes unless fluid is withdrawn. Under these conditions, where fluid is neither added or removed, the entire housing will rotate with the sun gear. The principle on which the coupling of Figures 10 and 11 operates is that the combined fluid flow from the two gear trains or pumps must be balanced by the fluid flow due to the rotation of the housing 100 which is connected to the output shaft 52. This relationship leads to the following expressions: Let: Q equal flow rate S equal speed of the shaft C equal capacity of gear pump Then 1. Q₁₀₂ + Q₁₀₄ = Q₁₀₀ And because Q = SC 2. S₁₀₂ C₁₀₂ + S₁₀₄C₁₀₄ = S₁₀₀C₁₀₀ Since C₁₀₂ = C₁₀₄ = 1/2 C₁₀₀ 3. 1/2 S₁₀₂ + 1/2 S₁₀₄ = S₁₀₀ This equation will be recognized as the same equation as that which describes the motion of the differential gear coupling 16. Thus, for the purposes of this invention, hydraulic differential coupling 99 is equivalent to and may be used interchangeably with the differential coupling 16. In addition to the three forms of converter mechanism disclosed, other forms may be used. For example, a spring or magnetically loaded coupling might be used as the converter mechanism. With particular reference to Figure 2, the location of the intake and exhaust ports can be determined by making certain assumptions. For example, a compression ratio of 8 to 1 can be specified. This ratio can be realized by allowing the closest proximity of the pistons to be 20° and the maximum spacing between the pistons to be 160°. Further, by assuming that the build-up of the pressure of the products of combustion is instantaneous and that the pistons have negligible momentum, the exhaust port should be located 20° off of the center line. Similar reasoning may be applied to dictate the location of the intake port. The engine design need not be limited to one intake or one exhaust port. In fact, the invention engine ideally lends itself to the use of a stratified charge, thus reducing air pollution without sacrificing performance. For example, one intake port could supply an enriched fuel mixture while a second intake port could introduce a lean mixture. Figure 2 also helps to illustrate a key feature of the invention whereby the pistons are free to move independently of each other. Because the pistons are free moving, they are able to automatically compensate or adjust to changes in operating conditions. For example, the point at which the abutment piston 34a comes to rest will depend upon such operating variables as the speed of the engine, its load, the ambient temperature, and the fuel composition. Thus, pre-ignition or knocking, as experienced in reciprocating engines using low octane gasoline, should have a minimum effect on the invention engine. Also, since the pistons are free moving, a major source of vibration, wear and inefficiency is eliminated. This feature also allows the invention engine to operate at much higher speeds as compared to other rotary engines or other engines of the reciprocating variety. Further modifications of the basic design of the invention engine are possible. For example, fuel injection may be used in place of a carburetor; and rather than employing a sparkplug to ignite the fuel mixture, a diesel configuration may be used. Also, more than one combustion chamber may be used to provide additional power. The advantages of the invention engine are numerous. Perhaps the most dramatic advantage as compared to conventional internal combustion engines is the extremely high power output per engine weight. Another striking feature is the engine's simplicity, which permits substantial savings in manufacture and maintenance. Because all moving parts are symmetrical, vibration is kept to a minimum, thus reducing noise, wear and inefficiencies. Fuel consumption also is thereby reduced. The engine's relatively high torque offers potential advantages in simplifying transmissions. Additional benefits also flow from the engine's small size and low profile which present many design advantages, particularly where streamlining is critical. The provision of means to deliver a charge under boost pressure is also extremely beneficial since it facilitates starting of the engine by providing relative rotation between the vanes; optimizes engine power under steady state operation by increasing the charge delivered to the engine; and precludes stalling of the engine under idling conditions by ensuring that a charge is delivered under pressure between the vanes. The invention engine has many practical applications. For example, the invention engine could serve as a replacement for the standard reciprocating automobile engine; the invention engine could find applications in aviation where high power to weight is critical and good fuel economy is required; and the invention engine could be used in lawn mowers and motorcycles where its small size, light weight and simplicity offer important advantages. Numerous military applications can also be imagined.

Claims: A rotary internal combustion engine comprising a housing (10) defining a combustion chamber (18), a first vane (34) mounted for rotation in the combustion chamber (18) about a fixed axis, a second vane (36) mounted for rotation in the combustion chamber (18) about the fixed axis independently of the first vane (34), control means (38, 40) for preventing rotation of either vane in one direction about the axis while allowing free rotation in the other direction about the axis so that the vanes may rotate freely in the other direction about the axis and may simultaneously undergo relative rotation, and converter means (16, 78, 190, 99), including an output shaft (52) drivingly connected to the vanes, and operative to convert the rotation of the vanes (34, 36) into unidirectional rotation of the output shaft (52), characterized in that said engine further includes means (64-76) for delivering a charge to said combustion chamber under boost pressure, said means comprising a supercharger (64) having a fluid outlet (76) in fluid communication with an intake port (22) of said combustion chamber (18) and supplying a stream of pressurized gas to said intake port (22), whereby the control means (38, 40) are such that during starting the relative rotation of the vanes (34, 36) is provided by the pressurized gas from the supercharger (64). A rotary internal combustion engine according to claim 1, characterized in that the supercharger (64) is drivingly connected to the output shaft (52) of said converter means (16, 78, 190, 99). A rotary internal combustion engine according to anyone of the claims 1 to 2, characterized in that the converter means comprise a pneumatic coupling (78) which is comprised of vanes (90, 92, 94, 96) which move in the same pattern as the vanes (34, 36) of the engine. A rotary internal combustion engine according to anyone of the claims 1 to 2, characterized in that the converter means (16, 78, 190, 99) comprise a hydraulic coupling (190). A rotary internal combustion engine according to anyone of the claims 1 to 2, characterized in that the converter means (16, 78, 190, 99) comprise a hydraulic differential coupling (99). A rotary internal combtion engine according to anyone of the claims 1 to 5 wherein a pair of concentric drive shafts (26, 32) are positioned on the axis and respectively drivingly secured to the first vane (34) and the second vane (36), characterized in that the shafts (26, 32) protrude axially out of one side of the combustion chamber (18) for connection to the control means (38, 40) and extend axially out of the other side of the combustion chamber (18) for connection to the converter means (16, 78, 190,99). A method of starting a rotary combustion engine of the type including two vanes (34,36) mounted for independent rotation in a combustion chamber (18) about a common central axis with the vanes (34,36) connected to concentric independent shafts (26,32) mounted on the axis, means provided to preclude rotation of each of the vanes and its associated shaft (26,32) in one direction about the axis but allowing free rotation of each of the vanes (34,36) and its associated shaft (26,32) in the opposite direction about the axis, and means (16) connecting the shafts (26,32) to an output drive member (52) through a differential mechanism allowing relative rotation between the shafts (26,32); characterized in that said output drive member (52) is rotated to rotate each of the vanes (34,36) in the one direction and boost pressure is introduced between the vanes (34,36) to urge rotation of one (34) of the vanes (34,36) in the one direction and resist rotation of the other (36) of the vanes (34,36) in the one direction to thereby provide relative rotation of the vanes (34,36), accommodated by the differential mechanism (16), to facilitate starting of the engine. A method according to claim 7 wherein said chamber (18) has an intake port (22) and the boost pressure is introduced between the vanes (34,36) by providing a supercharger (64) driven by the output drive member (52) and delivering the output of the supercharger (64) to the chamber intake port (22).

Inventors: STAUFFER, JOHN E.
Applicants: STAUFFER, JOHN E.
Application year: 1986
Main classification: F01C1
IPC codes: F02B53, F01B9, F01C1, F01C11