A portion of the disclosure of this patent document contains material that is subject to copyright protection. This patent document may show or describe matter that is or may become trade dress of the owner. The copyright and trade dress owner has no objection to the facsimile reproduction by anyone of the patent disclosure as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright and trade dress rights whatsoever.
1. Field: Rotary, internal combustion engines.
2. General Background and State of the Art: Internal combustion engines burn fuel in their combustion chambers in the presence of oxygen (usually from air). Burning generates high temperature and pressure gases, which expand and apply force against movable engine parts. Movement of the parts produce mechanical energy. Thus, an internal combustion engine converts potential chemical energy in the fuel into kinetic mechanical energy. Therefore, they provide the power for practical mechanical work to move vehicles and run pumps and other equipment.
Internal combustion engines fall into two principal categories, intermittent and continuous. Piston engines, either four-stroke and two-stroke, are the most common intermittent engines. Less common rotary engines also are intermittent. Continuous combustion engines include gas turbines and jet engines.
Internal combustion engines find their most common use in vehicles including cars, trucks, busses, airplanes and ships. The ratio of the potential chemical energy of the fuel (normally gasoline or diesel fuel) to the weight of the fuel is high. Consequently, internal combustion engines can travel long distance while carrying all their fuel.
Gasoline piston engines are among the least efficient internal combustion engine, only about 25%-30% efficient. Direct injection diesel engine may be about 40% efficient, at least at lower RPMs. Gas turbines are among the most efficient—approximately 60% efficient at high revolutions. However, gas turbines are inefficient at low revolutions. Because most land vehicle engines operate close to idle or well below maximum RPM, gas turbines usually are impractical for most land vehicles.
Rotary internal combustion engines surfaced in the early 1900s. See Hanley, U.S. Pat. No. 1,048,308 (1912). The Wankel rotary engine, which was developed beginning in the 1960s, became commercialized. See U.S. Pat. Nos. 2,938,505, 3,306,269, 3,373,723, 3,793,998, 3,855,977, 3,923,013 and 4,072,132. The Wankel engine is an internal combustion engine that uses a rotary design instead of reciprocating pistons to convert the energy of expanding combustion gases into rotating motion. Its four-stroke cycle takes place in a space between the inside of an oval-like epitrochoid-shaped housing and a rotor that is similar in shape to a Reuleaux triangle. The public often refers to the Wankel engine as the “rotary engine,” but rotary engines may have other constructions.
Internal combustion engines compress an air-fuel mixture in a combustion chamber and ignite the fuel by an electric spark or ultra high compression. The resulting combustion expands the gases to transform chemical energy into mechanical energy.
The combustion chamber in a gas turbine is between two sets of opposing fan blades. The fan blades compress the air mixture. When fuel is introduced and ignited, the combustion products expand against downstream fan blades causing the blades to rotate. The energy from the blade rotation drives the vehicle or other device.
a and 6b are partial front views of the rotary engine's rotor.
When the detailed description discusses a reference numeral in one or more drawing figures, the element and reference numeral being discussed is visible in that drawing. The element also may be visible in other figures without its reference numeral to avoid crowding of reference numerals.
A rotary engine has a rotor that has rockers pivoting in chambers inside an enclosed cylindrical housing. As each rocker pivots, it rotates an outer crankshaft. Each outer crankshaft has a spur gear that engages a stationary ring gear. Spur gear rotation causes the gears and the outer crankshafts to revolve around the ring gear. This causes the rotor to rotate.
As the rotor rotates, successive chambers are positioned at the intake, compression, ignition, and exhaust positions. In the intake position, the rocker pivots into its chamber to draw the air-fuel mixture into the chamber. The rocker pivots outward in the compression position. Igniting the fuel in the ignition position pushes the rocker inward, and the rocker moves outward again in the exhaust position to exhaust the combustion products.
Rotary engine 100 (
Housing 200 (
The housing may be air- or water-cooled. If water-cooled, the housing body may have top and bottom water troughs 210 and 220 (
Front plate 230 and rear plate 232 enclose housing 200 (
The front and rear plates 230 and 232 may include an oil ring seal groove 238 (only shown on plate 232 in
Power module 300 mounts within housing body 202. See
Arms 312, 314, 316 and 318 may be formed from two plates 340 and 342 that extend outward from hub 344 (
Plates for arms 312, 314, 316 and 318 may have aligned bores.
The space between one arm and its adjacent arm and inside cylindrical wall 204 of housing body 202 forms a chamber. Thus, chamber 360 (
One of four rockers 370, 372, 374 and 376 mounts for pivoting in each chamber 360, 362, 364 and 366.
Pivot pin 380 extends through ridge 382 of each rocker (
One may want to change parts if face 368 (
Front and rear ring plates 396 and 398 cover rotor arms 312, 314, 316 and 318, chambers 360, 362, 364 and 366 and rockers 370, 372, 374 and 376. See
The rockers' pivot pins such as pin 380 may extend into bores such as bores 394 on front ring plate 396 (
For positioning by hand, dowels may be used to align appropriate holes, e.g., hole 388 in ring plates 396 or 398, with the appropriate bore 386. Automated assembly may use different techniques.
The following discussion uses rocker 376 as an example for all rockers 370, 372, 374 and 376. Rocker 376 may include two spaced-apart pin bosses 410 and 412 (
Rockers 370, 372, 374 and 376 pivot about their respective pivot pins, e.g., pin 380 in rocker 376 (
Pivoting of each rocker 370, 372, 374 and 376 rotates a corresponding outer crankshaft 430, 432, 434 and 436 (7 and 8). Likewise, rotating an outer crankshaft pivots its corresponding rocker. The outer crankshafts may be made of 4140 steel. Though each could be formed of one piece,
Bolts 460 and 462 (
Front and rear wheels 440 and 442 of each outer crankshaft, e.g. crankshaft 436, may have an oil groove 480 and 482 (
Pressure from gases caused by ignition of fuel in the combustion chamber associated with rocker 376 pivots the rocker inward (i.e., right side moves downward in
Main crankshaft 610 is discussed before discussing the outer crankshafts' operation. The main crankshaft (
The longitudinal center of main crankshaft 610 may be hollow to transfer oil to outside the crankshaft and from one oil hole to another. For example, one or more oil distribution channels 640 (
Thrust ring 540, which may be bronze, mounts in thrust ring cavity 542 in rotor 310 (
Main crankshaft 610 extends through ring gears 620 and 622 and ring plates 396 and 398. The ring gears may be 4140 steel. The main crankshaft mounts in bores (only bore 510 is visible in
The teeth of front spur gear 450 and rear spur gear 456, which are associated with outer crankshaft 436 and rocker 376, engage the teeth on ring gears 620 and 622. Likewise, other spur gears on the other outer crankshafts, e.g., 432, 434, 436, associated with the other rockers also engage the teeth on the front or rear ring gear. Because the ring gears are stationary, spur gear rotation causes the spur gears to revolve around the ring gears. The connection of the outer crankshafts including their spur gears to rotor 310 causes the rotor to rotate about the rotor's axis of rotation. That axis coincides with the main crankshaft's axis of rotation.
In the figures, the spur gears travel around the outside of the ring gear. The ring gear could be a planetary gear with internal teeth so that the spur gears would travel around the inside of such a gear. Further, although the drawings show spur gears engaging a ring gear, the gears could be replaced with other devices such as belts, chain drives and friction drives capable of driving or being driven through their interaction.
The ratio of the number of spur gear teeth to ring gear teeth can be modified. Doing so changes the angular distance that rotor 310 travels for each rotation of the spur gears, e.g., gears 450 and 456.
Flanges 612 and 618 of main crankshaft 610 may extend through bores 244 and 246 in front and rear plates 230 and 232 (
Front and rear plates 230 and 232 may include oil ring seal groove 238 (only shown on plate 232 in
Ring plate seals 532 remain stationary with respect to housing plates 230 and 232 during rotor rotation. Thus, the rotor's ring plates 396 and 398 slide on the ring plate seal. The ring plate seals have an rim shoulder 534 as
The ring plates could have different designs, and
For the engine to operate, controlled amounts of air and fuel are injected through intake port 514 (
After chamber 366 receives a predetermined amount of air and fuel, rotor 310 rotation carries chamber 366 past intake port 514. Further rotation of the rotor causes outer crankshaft 434 to begin pivoting rocker 374 outward. Because the drawings are not animated and the components remain stationary, consider that chamber 366 has moved to the position where chamber 360 had been in the drawings and that the reference numerals for the parts that had been there now are used. As rocker (now 376) pivots outward, the decrease in volume in chamber 360 causes a corresponding pressure increase (compression) to the air-fuel mixture in the chamber above the rocker and in any recess 524 for a spark plug (discussed below).
The top surface of the rockers, e.g., rocker 376, may be coated. The top surface has central combustion region 402 (
Squish zone 408 may create turbulence by compressing the air-fuel mixture in the zone as the mixture reaches full compression over central combustion region 402. This may allow more complete burning of the gaseous mixture to decrease emissions. The squish zone also may improve exhausting of the remaining burnt gases. The surface of the squish zone may be 0.010 in. to 0.080 in. (0.25 mm to 2 mm) (metric equivalents are approximations) above combustion surface 402 with 0.020 in. to 0.060 in. (0.5 mm to 1.5 mm) possibly preferred.
The hot end of spark plug 520 (
The spark plug fires at a predetermined time for proper engine timing The ignition of the fuel in the presence of air in chamber 360 causes a substantial increase in pressure in the chamber. That pressure applies a force on rocker 376 to force the rocker inward. As rotor 310 continues rotating, what had been chamber 360 rotates into the position of chamber 362 in
Through the connection of outer crankshaft tang 436 with tang receiver 448, the inward movement rotates outer crankshaft 442. As a result, spur gears 450 and 456 rotate and travel along the outside of ring gears 620 and 622 (
Continued rotation of rotor 310 positions the chamber in question to the position of chamber 364 in
During each revolution of rotor 310, each of the four chambers sequence through four cycles: intake, compression, combustion and exhaust. By choosing the offset pivot of the rocker link, e.g., link 418 relative to its outer crankshaft 436 and to its rocker 376 (
In addition, the intake and exhaust ports 514 and 516 (
Note that only the outer crankshaft positioned with the rocker moving from combustion-caused expansion receives power directly from that combustion-caused pressure acting on the rocker. Through rotation of that outer crankshaft's spur gear acting on ring gears 620 and 622, rotor 310 rotates. At the same time, continued rotation of the rotor causes the spur gears for the other three outer crankshafts to rotate, which, in turn pivots the rocker associated with the crankshaft to pivot in or out. However, as each spur gear moves to the power/combustion position where the air-fuel mixture ignites, expanding gases drive the rotor inward. Consequently, that set of spur gears become the driving gears, and the other spur gears become driven gears.
The rear face of front ring plate 396 and the front face of rear ring plate 398 are against the respective sides of rotor 310. Each side of the rotor may have a sealing groove 530 that may run along the periphery of the arms. See
Main crankshaft 610 extends through collar 248 (
Components may have channels and openings for coolant and lubricant. These are not explained in detail and may vary with different engine sizes and designs. However, see openings 346 and 348 (
The size of the engine compartment and the position of the rotary engine in the engine compartment may affect the various components' locations insofar as they must fit in the compartment and may need to be accessible for service.
Belts or other connectors (not shown) may drive the alternator and other devices from engine power.
In one position in
The rotary engine that has been described is a four-stroke engine, intake, compression, combustion and exhaust. In a four-stroke piston engine, those strokes occur every two rotations or the crankshaft. Two-stroke piston engines complete a cycle in two movements of the piston, in and out. The rotary engine could be modified into a two-stroke engine. Two- and four-stroke designs have advantages and drawbacks relative to each other.
A typical use of internal combustion engines is in vehicles. Just as piston engines come in different sizes, compressions, power rating and other factors for different vehicles, the rotary engine's specifications can vary. Insofar as the rotary engine powers generators, pumps, machinery or other devices, the engine may have different designs. Some might require higher speed but less low-speed torque. Other application may require high torque at low speed. Some application may require constant output over long periods. Adjusting the combustion chamber volume, the size and pivoting angle of the rockers and other factor of the rotary engine may be modified to satisfy an engine's requirements.
At least two ways allow matching output power to power needs. The first is to have larger combustion chambers with larger rockers. Increasing the diameter of rotor 310 may allow the rockers to pivot through a larger angle to increase displacement. Likewise, increasing the width of the rotor also increases the displacement of each chamber. Optimizing performance may require balancing the effect of increasing the rotor's diameter and width. For example, increasing dimensions weight of all components and may affect other engine components or engine symmetry.
Stacking two or more power modules along the main crankshaft also could combine the modules' power output. In addition, combinations of different sized power modules can be assembled into one unit.
Though the configuration just described are internal combustion engines, the device with modifications can become a compressor. Compressor 800 (
Housing body 802 includes one or more inlets 820 and 824 and one or more outlets 826 and 828 (
Rotor rotation causes the rockers to pivot in an out. The inlets are positioned to receive air, other gas or liquid (“fluid”) either from the atmosphere in the case of air or from a source of fluid. The fluid flows into one of the rotor chambers as the rocker pivots inward to lower the pressure. When the rotor rotates away from the inlet, the rocker pivots outward to compress the fluid and force it through an outlet. With a four-chambered rotor, the rotor rotates to another inlet, draws fluid into the chamber and then compresses the fluid as the rotor moves adjacent another outlet.
Four strokes are not necessary. Thus, pressurized fluid can flow out an outlet at all compression strokes (pivoting outward of the rocker). Accordingly, the rotor could have two, four, six or more chambers with a corresponding number of rockers and outer crankshafts subject to space limitations.
Rotor 910 has eight arms 912, 914, 916, 918, 920, 922, 924 and 926. Adjacent arms form eight chambers such as chamber 930 between arms 914 and 916 and chamber 923 between arms 916 and 918. The inner cylindrical wall (not shown) of the housing receiving rotor 910 forms the outside of each chamber. Rocker 934 mounts near the distal end of arm 916 and pivots in and out of chamber 930. It is shown in in
The rotor is formed of front plate 940 and a corresponding rear plate, which is not visible in
The rotor may have additional bores such as bores 950 and 952 to decrease weight. The bores also may carry lubricant.
The outside of each arm that contacts or is close to contact with the cylindrical wall of the housing may have two grooves, e.g., grooves 958 and 960, which receive seals (not shown). Other seals for sealing the chambers and the rotor itself are not shown.
In the eight-chamber version, the air-fuel mixture ignites simultaneously in two chambers on opposite sides of the housing. Thus, during each rotor rotation, each chamber completes eight cycles (intake, compression, power, exhaust, intake, compression, power, and exhaust). Engines with 12, 16 or more chambers per rotor are contemplated. They may be particularly useful for large and heavy equipment such as earth movers, mining dump trucks, and cranes.
Crossover seal 1100 is configured to seat within the space between extensions 322 and 324. In operation, in the exemplary embodiment, first seal 1102 is forced in a first direction and second seal 1104 is forced in a second direction opposite the first direction. Spring 1112 located in a seal spring cavity of rotor 310 and recess 1110 forces seals away from one another in a lateral direction. In this implementation, as edges 1106 and 1108 wear and recede, spring 1112 forces seals 1102 and 1104 towards ring seal assembly 1000 to maintain a constant seal within combustion chambers to maintain a constant pressure. Additionally, a top surface 114 of seals 1102 and 1104 contacts and seals against the inner diameter of sleeve 1300 or directly against the inner diameter of housing 1200. As edges 1114 wear and recede, spring 1112 and centrifugal force seal 1102 and 1104 towards the sleeve 1300 or housing 1200 inner diameter to maintain a constant seal and/or pressure within combustion chambers. In the exemplary embodiment, a crossover seal width is larger in arc length than the diameter of the spark plug and/or injector ports in sleeve 1300 and/or housing 1200 to maintain a constant pressure and avoid leakage through such ports. The sealing by crossover seal 1100 creates a sealing force that substantially prevents chamber crossover leak and chamber cross-talk and substantially prevents crankcase pressurization.
In another implementation, a fluid or gas pressurization is maintained in the seal spring cavity to force first and second seals 1102 and 1104 laterally outward opposing each other and radially outward together. Utilizing fluid or gas pressurization enables the engine to maintain a regulated constant sealing force or an RPM linked sealing force. A fluid pressurization system also enables a pump oiling system to provide lubrication to crossover seal 1100 as well as potentially cool seal 1100 from an underside.
Sleeve 1300 is configured to act as an intermediary part between housing 1200 and power module 300. Sleeve 1300 is designed to be scalable from 50 milliliters to over 200 liters through an increase either in chamber (and piston) size or a stacking of power modules or both. Sleeve 1300 is fabricated to interface statically, via a tight tolerance press or clamp, with an inner surface 1202 of housing 1200 around an outer surface perimeter 1302 of sleeve 1300 along all or a part of an axial length of sleeve 1300. In the exemplary embodiment, the sleeve includes tabs or flats 1304 that mate with housing recesses or flats 1204. Similar to housing 1200, sleeve 1300 includes an inlet 1306, an outlet 1308, at least one entry point 1310, and an access point (not shown). Sleeve 1300 interfaces statically with main unit 1200 around housing inlet 1206, housing outlet 1208, and at least one entry point 1210 to provide a substantially leak-free flow path connection (e.g., not a pass-through) with inlet 1306, outlet 1308, and at least one entry point 1310 respectively.
Sleeve 1300 can have a varied wall thickness depending on design demands and sizing. In one embodiment, the sleeve wall thickness ranges from 0.1 inches to 0.75+ inches. In the exemplary embodiment, sleeve 1300 wall thickness is between 0.15 inches and 0.5 inches. Alternatively, sleeve 16 can have any wall thickness that facilitates sealing as described herein. Sleeve 16 can utilize housing 1200 as a mechanical support for backup on outer diameter 1200 for increased hoop stress and mechanical integrity. Additionally, sleeve 16 can function as a heat conductor to move heat away from combustion chambers and into housing 1200. Sleeve 1300 provides improved serviceability by allowing a worn or contaminant gouged power module crossover seal interface surface to be easily replaced without requiring replacement of an entire housing.
The use of housing 1200 and sleeve 1300 enables the material not in direct contact with power module crossover seals 1100, (i.e., housing 1200), to be made from a lighter weight and better heat conducting material since it does not receive any wear from seals 1100. Additionally, the use of sleeve 1300 enables the surface contacting the power module's crossover seals 1100 to be made from a heavier, stronger, longer wearing, and lower coefficient of friction material to endure the wear. As such, sleeve 1300 interfaces with power module 300 dynamically through crossover seals 300 to provide a seating-in, sealing, and wear surface for crossover seals 1100. Sleeve 1300 also forms an outward most chamber sliding surface area for pistons in power module 300.
The use of sleeve 1300 enables a flow path through housing inlet 1206 and housing outlet 1208 to be varied in cross-sectional area through sleeve changes. For example, intake 1306 having a smaller cross-section shape than housing inlet 1206 enables intake 1306 to reduce the flow path through housing inlet 1206 to the cross-sectional size and/or shape of intake 1306. As such, ports 1302, 1306, and 1308 can change a flow path into and out of combustion chambers. Changing a cross-sectional area of a flow path is similar to changing a valve size, which affects a duration and final chamber charge and/or discharge. Such a variation is similar to a cam lobe height affecting lift and cam lobe rise angle affecting lift rate, which affects duration and flow rate in an engine. In one embodiment, a port “width”, defined as the maximum dimension parallel with the sleeve axis, and a port “length”, defined as the maximum dimension perpendicular to the sleeve axis and along the sleeve's inner surface circumference. In this embodiment, “width” is akin to a lift rate and “length” is akin to a duration. A square port geometry with a side parallel to crossover seal 300 would give immediate high flow, which would simulate a very high lift rate and would have a long duration. A square port geometry with a diagonal perpendicular or parallel to crossover seal 1100 (e.g., a diamond) would give linear gradual increase to a high flow, which would simulate a nominal lift rate and would have a very long duration. As shown in
In one embodiment, sleeve 1300 enables a flow path entry or exit angle through housing inlet 1206 and housing outlet 1208 to be varied through sleeve changes. As such, having a housing inlet 1206 and/or housing outlet 1208 centerline non-continuous with that of sleeve intake 1306 and sleeve exhaust 1308 affects flow path angles through housing inlet 1206 and housing outlet 1208 relative to a location of piston head 402. As such, housing inlet 1206 and housing outlet 1208 flow path centerlines can be brought closer together or farther apart by use of sleeve 1300 thus controlling the overlap or time in which both housing inlet 1206 and housing outlet 1208 are both open to the same chamber.
In another embodiment, sleeve 1300 enables flow paths through housing inlet 1206 and housing outlet 1208 to be varied in axial neck-down or open-up geometries through sleeve changes. Flow through housing inlet 1206 and/or housing outlet 1208 going neck down in cross-sectional area from sleeve 1300 outer surface to sleeve 1300 inner surface will increase gas velocity flow through sleeve inlet 1306 and reduce the velocity through sleeve outlet 1308. Alternatively, flow through housing inlet 1206 and/or housing outlet 1208 being spread out in cross sectional area going from sleeve 1300 outer surface to sleeve 1300 inner surface will decrease gas velocity flow through sleeve inlet 1306 and increase velocity flow through sleeve outlet 1308. Such an embodiment supports controlling the duration or time in which a passing chamber sees housing inlet 1206 open or housing outlet 1208 open in degrees of power module rotation. As such, sleeve can be configured to affect duration, which can, in turn, affect charge and/or discharge velocity impacting engine torque and engine horsepower.
In another embodiment, sleeve 1300 enables housing inlet 1206 and housing outlet 1208 relative centerline locations, and hence timing, to be varied via the circumferential positioning of the intake 1306 and exhaust 1308 of assembly 1300. Where the trailing edge of a chamber's crossover seal tangent line is relative to the trailing edge of exhaust port 1308 on sleeve's inner surface and where the leading edge of a chamber's crossover seal tangent line is relative to the leading edge of the intake 1306 on the sleeve's inner surface affects how long intake 1306 and exhaust 1308 are open together into a chamber. As such, entering intake 1306 can help push out escaping exhaust and escaping exhaust can help draw in entering intake air.
In yet another embodiment, sleeve 1300 enables the position of injector ports 1210, for direct injection, to be varied relative to piston assembly bottom dead center (BDC) through sleeve changes. As such, sleeve 1300 can affect and/or change fuel timing by simply changing sleeve 1300 in housing 1200. Likewise, sleeve 1300 enables the position of spark plug port 1210 to be varied relative to piston assembly top dead center (TDC) through sleeve changes. As such, sleeve 1300 can affect and/or change typical ignition timing. Additionally, port variations also enable the engine to run on different fuel types by utilizing a sleeve 1300 which can enable the engine to operate according to the requirements of a particular fuel type.
When detailed descriptions reference one or more drawing figures, the element being discussed is visible in that drawing. The element also may be visible in other figures. In addition, to avoid crowding of reference numerals, one drawing may not use a particular reference numeral where the same element is in another drawing with the reference numeral.
The description is illustrative and not limiting and is by way of example only. Although this application shows and describes examples, those having ordinary skill in the art will find it apparent that changes, modifications or alterations may be made. Many of the examples involve specific combinations of method acts or system elements, but those acts and those elements may be combined in other ways to accomplish the same objectives. With regard to flowcharts, additional and fewer steps may be taken, and the steps as shown may be combined or further refined to achieve the methods described. Acts, elements and features discussed only in connection with one embodiment are not intended to be excluded from a similar role in other embodiments.
“Plurality” means two or more. A “set” of items may include one or more of such items. The terms “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” and the like in the written description or the claims are open-ended, i.e., each means, “including but not limited to.” Only the transitional phrases “consisting of” and “consisting essentially of” are closed or semi-closed transitional phrases with respect to claims. The ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element do not by themselves connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed. Instead, they are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term). Alternatives such as “or” include any combination of the listed items.
This application is a continuation-in-part application of U.S. patent application No. 12/637,595, filed Dec. 13, 2009, which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
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Parent | 12637595 | Dec 2009 | US |
Child | 13843758 | US |