US 20070137595 A1
A power plant utilizing a radial rotary engine and incorporating onboard energy storage. The engine is of the type utilized in pre-World War I aircraft, but with certain modifications. The energy storage system exploits the flywheel effect inherent in these engines and optionally also includes auxiliary energy storage in other forms, such as compressed air or electrical. Using a continuously variable transmission enables advantageous use of engine inertia in a coast down mode of driving.
1. A power system including a radial rotary internal combustion engine as a prime mover, and a power transmission element capable of outputting power selectively from both active internal combustion power production and also inertia of engine rotating mass, wherein said engine includes
a rotatable cylinder block disposed to rotate about an axis of rotation and having formed therein a plurality of cylinders generally oriented to radiate from said axis of rotation, a piston reciprocatingly disposed within each one of said plurality of cylinders, a stationary crankshaft, and a unitary connecting rod encirclingly engaging said crankshaft and pivotally connected to each said piston, wherein said crankshaft has a longitudinal center line offset from said axis of rotation of said cylinder block such that rotation of said cylinder block and pistons about said crankshaft produces apparent reciprocation of each one of said pistons relative to each one of said plurality of cylinders, and
a rotation adjuster disposed to move said crankshaft to a second axis of rotation displaced from said first axis of rotation such that said rotatable cylinder block rotates about said second axis of rotation and each one of said cylinders is located such that said piston of each one of said cylinders avoids causing displacement within its respective said cylinder.
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This application claims the benefit of U.S. Provisional Patent Application Ser. No. ______ filed on May 13, 2004 as Attorney Docket Number D2GRE001.11.
The present invention is directed to a power system including a radial internal combustion engine serving as a prime mover, and an associated energy storage system which cooperates with the radial engine.
Internal combustion engines have long been used to power transport vehicles on land, in and on water, and in the air. Initially, internal combustion engines were directly connected to wheels, propellers, and other elements of a vehicle which acts on an environmental medium to effect propulsion. In some applications, power generated by internal combustion engines has been transformed before bearing on the propulsion effecting elements of the vehicle. For example, diesel electric railway locomotives have diesel engines serving as prime movers which power generators, which generators in turn supply electrical power to drive motors which rotate wheels. In a further development, internal engines have been utilized to store power onboard a vehicle. A well known example is that of electric boats, particularly of the submarine type. Submarine type vehicles have both liquid fuel tanks and also storage batteries. Output of the internal combustion engine can be exploited to rotate a propeller or to charge the batteries.
The recent automotive development of so-called hybrid vehicles has demonstrated that remarkable fuel savings are enabled by combining internal combustion and electric power plants in a transport vehicle. A hybrid vehicle has both an internal combustion engine and also an electric motor which may, depending upon the specific design, may individually and collectively be brought to bear on propulsion of the vehicle. Arrangement of different hybrid schemes vary, but one element all hybrid schemes have in common is that power demanded of an internal combustion engine over time is far more constant than is the case with vehicles wherein an internal combustion engine is not supplemented by electrical power.
Considering now the internal combustion engine which is selected for use with hybrid vehicles, contemporary practice is limited to those engines wherein at least one and usually a plurality of pistons are reciprocatingly disposed within bores or cylinders formed in a stationary structural engine block. Each piston is operably connected to a rotary crankshaft by a connecting rod. The output of these conventional engines is one or more rotating shafts, which are drivably connected to a suitable transmission, to a generator, or to another element for inducing propulsion. While these engines are entirely operable, they fail to exploit certain characteristics which are available in internal combustion engines. One of these characteristics is use of the flywheel effect, wherein inertia of a relatively large or heavy rotating mass may be exploited to provide power independently of the energy being liberated in the combustion chambers, at least for a temporary period of time. While conventional engines can be fitted with suitably heavy flywheels or other rotatable masses, this comes at a detrimental cost in conventional engines. That is, total weight of the engine is increased. There is a need for an engine which overcomes this situation while still providing the benefits of the flywheel effect.
A second characteristic is that while apparent reciprocation between piston and engine block occurs, this is not at the full cost in energy of periodically accelerating and decelerating the pistons within the engine block, as occurs in stationary block engines. Because the engine block defining the combustion cylinders rotates about an axis offset from that of the crankshaft to which the pistons are connected, at least a component of the apparent magnitude of reciprocation of the pistons occurs without axially accelerating each piston the full extent of the apparent stroke.
There exists an engine design which provides a relatively large rotating mass without arbitrarily increasing total engine mass, and which provides piston reciprocation which does not require periodic accelerations of each piston in alternating directions. In the early twentieth century, a radial rotary engine was developed for use with aircraft. This engine, which came to be known as the “Gnome” radial engine, essentially caused the engine block and cylinder heads to rotate about the crankshaft, which remained stationary relative to its associated vehicle. In practice, the crankshaft was secured in fixed relation to the fuselage of the aircraft. The propeller was fixed to the rotating engine block, which propeller and engine block then rotated as a unitary element. This arrangement was responsible for remarkable advances in early aircraft performance as regards aircraft velocity. A drawback of the engine in the environment of small aircraft was the gyroscope effect developed by the rotating mass, which introduced difficulties in steering the aircraft. As these small aircraft were combat aircraft, with maneuverability being a particularly prized characteristic, this early engine fell from favor despite some advantages which remain to this day. It would be desirable to utilize the advantages of a rotary block, reciprocating piston internal combustion engine in stored energy hybridized vehicles today.
The present invention combines the advantages of a rotary block, reciprocating piston internal combustion engine with an energy storage system to improve on benefits which accrue from today's hybrid vehicle arrangements. To this end, the present invention uses an improved rotary block radial engine in combination with one or more energy storage systems which can release power independently of power being developed within the engine by combustion of the fuel at any one instant in time. This engine provides a large rotating flywheel mass with no attendant increase in overall mass, minimal reciprocating load of pistons, and frequency in firing of a two stroke cycle engine.
Engine output is supplemented by stored energy. In one embodiment, this stored energy takes the form of compressed gasses which have been generated by the engine and stored. In another embodiment of the invention, electrical energy rather than compressed gasses may be generated and stored. Advantageously, when power from internal combustion is not required, combustion may be discontinued and the pistons may then be exploited to serve as a compressor.
When power is not required, a mechanical adjustment to the crankshaft is made. This adjustment permits the engine block and pistons to rotate without imposing a driving force on the crankshaft. Thus that energy originating in the engine and presently taking the form of kinetic energy may be conserved without dissipation which otherwise would be caused by decelerating the engine back to the stationary condition. As a consequence, combustion which would merely waste fuel when idling may be discontinued. The engine block with its relatively great mass would continue to rotate. This permits power to be derived from a flywheel effect and also eliminates the step of rotating the internal combustion engine when restarting it.
The engine is improved over the early aircraft engine in several preferred yet optional ways. One is that it is preferably although not necessarily operated as a diesel. A second is that an adjustment feature is provided which enables the engine to change its operation from that of an internal combustion engine to that of an air pump. A further improvement is that of making the crankshaft adjustable such that the pistons orbit ineffectually thereabout in tandem with the rotating engine block, so that the engine rotates without idling or active power production. Still another improvement is providing stepped pistons wherein an air suction chamber is provided which is greater in volume than the combustion chamber, thereby achieving a supercharged effect with no additional moving parts. Valves may be of the exposed port type, or alternatively of the poppet type. Where gas compression and storage is selected for energy storage, engine exhaust heat may be used to increase pressure of stored compressed gasses. Gasses may include both atmospheric air and also exhaust gas. A further improvement incorporates a recirculating lubrication system rather than the “one use” system originally provided wherein lubricant was ejected from the engine after a single introduction to a piston and cylinder assembly.
It is an object of the invention to utilize a rotary radial engine having a stationary crankshaft and minimal parasitic piston reciprocation losses as a prime mover in a hybrid power plant which incorporates selectively releasable energy storage.
It is another object to modify a rotary radial engine to enable engine block rotation to achieve a flywheel effect without idling.
It is a further object of the invention to modify a rotary radial engine to incorporate a recirculating lubrication system.
It is still another object of the invention to provide a supercharging feature with minimal increase in moving parts.
Still another object of the invention is to supplement stored energy in the form of compressed gasses with heat derived from waste exhaust heat.
It is an object of the invention to provide improved elements and arrangements thereof by apparatus for the purposes described which is inexpensive, dependable, and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.
Various objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:
The present invention combines the attributes of a radial rotary engine 10 with an energy storage system. Referring first to
It will be appreciated that for visual clarity, certain necessary features of engine 10 are omitted from view in
In the embodiment of
Turning now to
When piston 12 descends, exhaust passage 46 is uncovered, as shown in
While engine 10 is capable of producing torque as a consequence of internal combustion during rotation, it is desired to exploit an inherent energy storage characteristic of radial rotary engines. That is that because the cylinder block rotates about stationary crankshaft 22, ordinary engine operation generates a flywheel effect which is much greater than for stationary block, rotary crankshaft engines (not shown). Inertia of this rotating mass can be conserved to a considerable degree without requiring internal combustion to proceed. Turning now to
Any suitable mechanism or rotation adjuster, some being known, may be employed to make this adjustment. Illustratively, a pivotal lever which may be moved manually or under power, such as by electrical power, may swing crankshaft 22 in an arcuate path established by guides. A purely illustrative example is shown in
The major rotating parts of engine 110 can function as a flywheel, without consuming fuel by idling, and with minimal frictional losses when crankshaft 104 is appropriately adjusted. This may be exploited to add to power available when conducting internal combustion, on its own should engine 110 be modified to include a mechanical connection (not shown) thereto in the idle mode, by incorporating electrical generating apparatus into the cylinder block (not shown) of engine 103, or in any other known way of exploiting inertia of a rotating mass.
Power generated by engine 103 above that required for vehicle propulsion and associated support functions such as power for external signalling, exterior illumination, general interior lighting, heating, cooling, ventilation, onboard audio and video equipment, communications equipment, and the like, may be apportioned to the auxiliary power output element by microprocessor 122. Conveniently, energy can be stored even while the vehicle is moving, without increasing or modifying engine rotational speed whenever available power at a selected engine speed exceeds demands for propulsive and support power. In the illustrative example of
It is presently contemplated that an advantageous energy storage system could, either in place of or in addition to a generator, be provided by an air compressor. Referring now to
It would be possible to modify engine 203 by suitable changes to air exhaust valves (not separately shown) and their associated passages and by discontinuing combustion and operating engine 203 as a pump. A conventional exhaust conduit may be routed in close proximity to the compressed air receptacle. This increases effective pressure of stored compressed air, using only otherwise waste heat of the exhaust.
In an advantageous use of the invention, a motor vehicle (not shown in its entirety) is driven in a “coast down” mode wherein once a predetermined vehicle speed is attained, engine operation is changed from active power generation through internal combustion to rotation only. In the “rotation only” mode, pistons undergo no displacement and merely rotate together with the cylinder block. Stored inertial energy may then be applied for vehicle propulsion. Speed may be maintained relatively constant where a continuously variable transmission is employed. Alternatively, in the absence of a continuously variable transmission, a constant ratio transmission may connect the rotating mass to the vehicle drive wheels. When a predetermined minimum vehicle speed is reached, the crankshaft may be adjusted to reestablish internal combustion operation. The speed of the vehicle may be progressively increased to the predetermined high speed, at which point a new coast down cycle may be put into play. Prior experiments have shown that this is an effective strategy in increasing average fuel mileage. It is currently believed that one source of efficiency is that of utilizing the engine only at full volumetric efficiency when internal combustion occurs. The flywheel effect tends to oppose rapid speed loss and thus reduces frequency of switching between active power operation and coast down operation.
The exact nature of engine 10 or 103 may be varied to suit. The selected form of the engine may encompass either two stroke cycle operation or four stroke cycle operation, depending upon the valve system provided. It is also optional to switch operation between two stroke and four stroke cycles by appropriate manipulation of valving. Combustion may be either of the compression ignition type or of the spark ignition type, with appropriate fuel and ignition systems being fitted to the engine.
In some engine operation regimens, it may be necessary to have poppet valves in place of the inlet ports and exhaust ports shown for the previously described embodiments.
Tappet 142 rotates in tandem with cylinder block 138, and is operated by a cam lobe 150. Cam lobe 150 is fixedly mounted on a an enlarged portion of crankshaft 136, or cam carrier 152. It will be appreciated that although cam lobe 150 is a fixed or stationary component of engine 132, rotation of cylinder block 138 causes mutual motion with cam lobe 150. Cam lobe 150 therefore operates in conventional fashion despite its unconventional location.
Both the valve elements including tappet 142, pushrod 144, and rocker arm 146, and also fuel injection plunger 156 may be returned to their initial positions in known fashion by respective return springs (not shown). It will be appreciated that where necessary to achieve different timing and duration characteristics, different tiers of cam lobes may be provided for the fuel injection and valve systems. Also, where it is desirable to vary timing of one set of cam lobes independently from the other, separately controlled concentric sleeves (not shown) may be provided in encircling relation about crankshaft 136. These sleeves may each be operated by a motor such as motor 116 of
Cylinder block 238 has a shaft 240 which is supported on radial bearings 242 and thrust bearing 244 (shown representatively rather than literally). Bearings 242, 244 are mounted in a suitably sturdy frame or support member 246. Preferably, bearings 242 and 244 are of the self-sealed type used to support wheels on stub axles in conventional wheeled road going vehicles, and are independent of the forced lubrication system. Mounted to shaft 240 are a toothed wheel or gear 248, a coolant pump 250, and an oil pump 252. An electric starter motor 254 is operably connectable to gear 248. Pumps 250 and 252 may be, for example, of the eccentric lobe type, where an eccentric lobe (not separately shown) is driven by shaft 240. Outputs of pumps may be conducted by suitable conduits to the points of use or to intermediate conduits as necessary.
Fluids necessary for supporting functions are introduced into cylinder block 238 through an intake conduit 256. The nature of intake conduit 256 is better understood by examining
A second passageway 262 is arranged concentrically about yet isolated from passageway 258. Unlike passageway 258, which is open at both top and bottom, passageway 262 has an upper wall 264 to constrain fluids to communicate at the top only with a tube 266. A third passageway 268 is concentrically disposed about passageway 262, again isolated therefrom. Passageway 268 has an upper wall 270 and is in communication with a tube 272. The outer wall of each passageway 258, 262, or 268 has an associated seal, such as a compressible O-ring 274, 276, or 278.
Again referring to
Illustratively, coolant may be pumped from pump 250 to a liquid-to-air heat exchanger such as a conventional radiator, then to inlet tube 266 (see
A suitable lubricant such as engine oil may be pumped from pump 252 to a suitable oil filter (not shown), through an oil cooler if desired, and then to tube of intake conduit 256. Oil then passes through passageway 268 (see
Exhaust is conducted from individual cylinders in a manner similar to that of the embodiment of
In a currently preferred embodiment of the invention, engine 210 is a compression ignition or diesel engine. Glow plugs (not shown) are provided in their customary relationship to the combustion chambers. Glow plugs may be connected to power for engine starting in the following way. A solenoid plunger operated switch 288 is provided for each cylinder. Each switch 288 is connected to power from a battery (not shown). Each switch 288 includes a contact which projects such that it contacts a corresponding contact formed on cylinder block 238. The corresponding contacts may be rings disposed continuously about and concentrically to the rotational axis of cylinder block 238. Alternatively, they may be of relatively small size and in a predetermined location. Coordination of alignment between the stationary and mobile contacts may be achieved by manually adjusting cylinder block 238 to a predetermined location. Alternatively, cylinder block 238 may be arranged to come to a stop at a predictable angular position by utilizing resistance of compression, especially where a relatively small number of cylinders, such as two or three, is utilized.
Similar switches (not shown) may be provided to provide a ground path. Alternatively, switches 288 may be provided with additional contacts for this purpose. Electrical power supplied through switches 288 is appropriately insulated from ineffective contact to ground, and is conducted to the glow plugs. Solenoid switches 288 are de-energized to retract by spring force after sufficient time to warm the glow plugs adequately. Engine 210 may then be started by rotating cylinder block 238 by starter motor 254. Preferably, the starting system includes a temperature sensor (not shown), so that when the engine is sufficiently warm to effect combustion spontaneously from the fuel injection system, glow plug operation will not be activated.
Although not shown, fuel may be supplied to fuel injectors (not separately shown) mounted in the cylinder block assembly in a manner similar to that shown for coolant and lubricant. Preferably a relatively low pressure fuel supply pump is provided, with final high pressure being supplied by plungers such as that described with reference to
It should be understood that certain modifications may be made to the embodiments described herein. For example, the number of engine cylinders may be at least two, and any number as desired. As a practical matter, the maximum number of cylinders is held to be about nine, since beyond that number, interference problems occur and the magnitude of the stroke becomes excessive compared to magnitude of the bore for each cylinder.
Arrangements for aspirating the engine other than those shown herein may be utilized, with appropriate modification to valving, porting, and the like. Poppet valves and exposed port valves may be changed to other types where desired. The stepped piston design described herein may be modified to eliminate that construction, may be modified to achieve supercharging in another way, or to eliminate supercharging.
Brushes (not shown) may be employed to conduct electrical signals into the rotating cylinder block where desired.
The descriptions of the preferred embodiments are not to be construed in a limiting sense but rather in illustrative capacity. The scope of the invention should be interpreted according to the appended claims.