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Publication numberUS3685498 A
Publication typeGrant
Publication dateAug 22, 1972
Filing dateMar 24, 1971
Priority dateMar 24, 1971
Publication numberUS 3685498 A, US 3685498A, US-A-3685498, US3685498 A, US3685498A
InventorsShrewsbury Robert M, Walcker Jake J
Original AssigneeWalcker Jake J, Shrewsbury Robert M
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Rotary engine
US 3685498 A
Abstract
A two-stroke cycle, internal combustion engine in which pairs of hollow pistons are fixedly mounted on opposite sides of a hollow stationary shaft, and radially arranged cylinders revolve about a crank pin on a rotary drive shaft, said shafts being aligned on a common axis. The cylinders also orbit in a circular path about said axis, and the speed and direction of rotational and orbital movement are synchronized by a stationary gear coaxial with said drive shaft and meshing with a ring gear that is centered with respect to the cylinders. There are twice as many cylinders as pistons, and each piston leaves one cylinder at the end of its power stroke and enters another cylinder 180 DEG around from the first at the beginning of its next compression stroke. Fuel is injected into the combustion chambers through nozzles in the pistons. Spark plugs (if used) are mounted on the outer ends of the pistons. Fuel lines and ignition wires pass outwardly through the hollow stationary shaft. Air is blown through the stationary shaft and hollow pistons to cool the latter, and jets of air are blown into the cylinders as each piston enters the cylinder, to scavenge any remaining combustion gas.
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Description  (OCR text may contain errors)

United States Patent Shrewsbury et al.

[ 1 Aug. 22, 1972 ROTARY ENGINE [72] Inventors: Robert M. Shrewsbury, 351 .3 Redlands Dr., Bakersfield, Calif. 93306; Jake J. Walcker, 286 Merrywood Circle, Mira Loma, Calif. 91752 [22] Filed: March 24, 1971 [2 11 Appl. No.: 127,569

[52] US. Cl. ..l23/8.09, 123/845, 4l8/6l,

418/91, 4l8/99, 4l8/l5l, 4l8/l6l, 418/187 [51] Int. Cl. ..F02b 53/00, F03c 3/00 [58] Field of Search ..l23/8.09, 8.45',4l8/6l, l6], 4l8/9l,99, l5l, I87

5/1970 Rashev ..4l,8/ l X PrimaryExaminer-Allan D. Herrmann Attorney-Herbert E. Kidder [57] ABSTRACT A two-stroke cycle, internal combustion engine in which pairs of hollow pistons are fixedly mounted on opposite sides of a hollow stationary shaft, and radially arranged cylinders revolve about a crank pin on a rotary drive shaft, said shafts being aligned on a common axis. The cylinders also orbit in a circular path about said axis, and the speed and direction of rotational and orbital movement are synchronized by a stationary gear coaxial with said drive shaft and meshing with a ring gear that is centered with respect to the cylinders. There are twice as many cylinders as pistons, and each piston leaves one cylinder at the end of its power stroke and enters another cylinder 180 around from the first at the beginning of its next compression stroke. Fuel is injected into the combustion chambers through nozzles in the pistons. Spark plugs (if used) are mounted on the outer ends of the pistons. Fuel lines and ignition wires pass outwardly through the hollow stationary shaft. Air is blown through the stationary shaft and hollow pistons to cool the latter, and jets of air are blown into the cylinders as each piston enters the cylinder, to scavenge any remaining combustion gas.

10 Clains, 7 Drawing Figures ROTARY ENGINE BACKGROUND OF THE INVENTION This invention pertains generally to internal combustion engines, and more particularly to a new and improved rotary engine utilizing pistons and cylinders in a fuel-injected, two-stroke cycle, in which the pistons are stationary and the cylinders revolve to turn the drive shaft. The engine of the present invention is equally well adapted for operation as a spark-ignition engine, or as a compression-ignition engine, and therefore can run on volatile liquid fuels, such as gasoline, butane, propane, or the like, or on fuels of lower volatility, such as kerosene, Diesel fuels, and the like.

One of the disadvantages of prior internal combustion engines is the large number of moving parts involved, which are expensive to manufacture and assemble, have large frictional losses that subtract from the net power output of the engine, contribute to vibration and noise, and wear out. Reciprocating parts such as pistons and connecting rods consume power to accelerate them from a standstill up to maximum velocity, and then slow them back down to a standstill again.

Another disadvantage of prior piston-driven engines is that they have about reached the peak of performance development from the standpoint of power per cubic inch displacement, and power per pound of engine weight. For unsupercharged high performance engines, used in non-racing automobiles and the like, the maximum power output ranges from about 0.50 to about 0.80 h.p. per cubic inch displacement, with engine weights ranging from 3 to 4 lbs. per horsepower. Highly developed racing engines have considerably better performance than this, but the cost is extremely high. Two-stroke cycle engines used in outboard motors and motorcycles also have high power-per-cubicinch and low weight-per-horsepower ratios, but at a cost of extremely high specific fuel consumption due to their wasteful discharge of large volumes of unburned fuel into the atmosphere, which makes them seriously objectionable because of atmospheric pollution.

SUMMARY OF THE INVENTION The primary object of the present invention is to provide a new and improved internal combustion engine of the two-stroke cycle, piston-and-cylinder type, having only three moving parts, exclusive of accessory equipment such as ignition system, fuel injection pump, starting motor, electrical generators, and cooling air blowers.

Another important object of the invention is to provide an engine of the class described in which there are no reciprocating parts, but only rotating parts.

Another object of the invention is to provide a fuelinjected internal combustion engine of high thermal efficiency due to good scavenging of the cylinders and to good turbulence of the air within the cylinder at the moment of fuel injection.

Thermal efficiency is further promoted by the high operating temperature of the engine, which results in more complete combustion of the fuel. Another advantage of the engine is that the hot exhaust gases are mixed with fresh air immediately upon leaving the cylinders, and this aids in oxidizing any unburned fuel in the exhaust, thereby reducing atmospheric pollution to an extremely low level.

A further object of the invention is to provide an intemal combustion engine having an extremely high power-to-weight ratio, and also a high power-percubic-inch ratio.

Still a further object of the invention is to provide an internal combustion engine of the class described, which is relatively lightweight, simple and inexpensive to manufacture, vibrationless and virtually trouble free.

The above objects are achieved by providing an engine in which pairs of pistons are fixedly mounted on opposite sides of a hollow stationary shaft, and an assemblage of radially arranged cylinders rotates about an eccentric crank pin on a rotary drive shaft. The rotary drive shaft and stationary shaft are axially aligned, and the cylinder assemblage orbits around the common axis of the shafts, while at the same time rotating about the crank pin. A central gear fixed to the stationary shaft meshes with a ring gear on the cylinder assembly, to synchronize the rotational and orbital movements of the assemblage so that the pistons are successively withdrawn from one cylinder and inserted into the opposite cylinder, spaced from the first. There are twice as many cylinders as pistons, and each piston leaves its respective cylinder at the end of the power stroke, and enters the opposite cylinder at the beginning of the compression stroke. Fuel is injected into the combustion chambers through nozzles in the outer ends of the pistons as each piston reaches the end of its compression stroke. The engine may be operated on either the Otto cycle or the Diesel cycle. If operated on the Otto cycle, spark plugs may be mounted in the outer ends of the stationary pistons. Ignition wires and fuel lines pass through the hollow center of the stationary shaft to external housing of the engine, where they are connected to their respective accessory units.

Among the advantages inherent in the abovedescribed construction are the following: (1) there is no reciprocating or oscillating movement in the engine all motion is pure rotational; (2) there are only three moving-parts, consisting of cylinder block, drive shaft, and a small, free-turning pinion gear; (3) the pistons do not touch the cylinder walls and therefore do not need lubrication, hence the engine can run much hotter than conventional engines; (4) any blow-by may be burned in an afterburner to reduce unburned fuel in the tailpipe emissions to an absolute minimum; (5) the fine tolerances and balance required by high speed are easily achieved because of the all-rotary motion of the engine; (6) the cost of close-tolerance machining and precision bearings is offset by the simplicity of construction no valves, valve springs, cam shaft, timing gears, connecting rods, etc.; (7) the cylinders are aircooled and light in weight; (8) air for supercharging also cools the pistons and scavenges the cylinders; (9) any number of cylinders can be turned around one crank-plate; 10) the engine is extremely compact, and has a high power output per cubic inch of displacement; (1]) it has the smoothness and high RPM of a turbine, with the high torque of a piston engine; (12) it is reversible, and will run equally well in either direction; and (13) almost any fuel can be used.

Other objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment thereof, with reference to the accompanying drawings.

v 3 BRIEF DESCRIPTION OF THE DRAWINGS:

- FIG. 1 is a sectional view through an engine embodying the principles ofthe invention; v

FIG. 2 is a reduced-scale sectional view through the same, taken at 2,-2 in FIG. 1, showing the relative positions of the cylinders, pistons, and counterweight for an initial position of the drive shaft;

. FIG. 3 is a view similar to FIG. 2, in which the drive shaft (and attached counterweight) have been rotated 90 in the clockwise direction, while the cylinders have been rotated 45? in the same direction;

FIG. 4 shows the drive shaft and counterweight rotated another 90 in the clockwise direction from the I positionshown in FIG. 3, while the cylinders have been rotated another 45";

FIG. 5 shows the drive shaft and counterweight rotated another 90 from the position shown in FIG. 4, with the cylinders rotated another 45; I FIG. 6 shows the engineafter one complete revolution of the drive shaft and counterweight; and

FIG. 7 is a sectional view taken at 7-'-7 in FIG. .1, showing the gear arrangement for synchronizing the rotation of the cylinders with their orbital movement 'aroundthe drive shaft.

' DESCRIPTION or THE PREFERRED EMBODIMENT;

ln'the drawings, the reference numeral 10 designates the engine in its entirety. The engine is shown with its drive shaft perpendicular,-but this is not essential, as the engine will operate equally well in any position. The

. operating mechanism is enclosed within a stationary housing 12 consisting of circular end walls 14 and 16, and a cylindrical outer wall 18 connecting the end walls. "Projecting through the center of the top 'end wall 16 (as seen in FIG. 1) andfixedly secured thereto, is a stationary hollow shaft 20. Axially aligned with shaft 20 onthe, opposite side of the housing is a rotatable drive shaft 22, which is joumaled in a bearing 24in the hous-- gear on the side diametrically across from pinion 62 is a larger diameter gear 66, which is fixedly mounted on chaft 20. The purpose of pinion "'62 is to press the cylinder block 36 in the direction to hold the ring gear 64 in mesh with stationary gear 66 as the cylinder block orbits around the latter-. I I

The pitch diameter of gear 66 isexactly one-half the pitch diameter of ring gear 64, which means that gear 66 has half as many teeth as gear 64, and therefore one orbital revolutionof the cylinder block 36 about the stationary shaft 20 causes the cylinder block to rotate a half revolution about .the'crank pin 30. The purpose of.

- this synchronized movement will becomc apparent as the description proceeds. I

Formed in the top side of the cylinder block is a central circular aperture 68, through which jets of air are directed from conduits 70. The conduits are connected to an external, engine-driven blower 72. On the bottom side of the cylinder block is a plurality of exhaust apertures 74 arranged in a circle concentric with crank pin 30. The housing 12 also has a plurality of exhaust outlets 76 arranged in a circle concentric with the drive shaft, and these are located so that as the cylinders orbit around the drive shaft and rotate about the crank pin 30, the apertures 74 pass in front'of the outlets 76, allowing the air from conduits 70, mixed with exhaust gases from the cylinders, to be discharged from the housing. Outlets 76 would, of course, be connected vto a suitable manifold, not shown, and be carriedthence to a muffler. Alternatively, the exhaust outlets 76 may be connected to an afterburner (not shown) where any unburned fuel remaining in the exhaust gases is oxidized. The fully oxidized exhaust gases leaving the af terbumer could be utilized to drive a turbine (not shown) which could serve as the motive power for blower 72.

Disposed within the cylinder block 36 are stationary pistons 78 and 80, which are mounted on opposite sides of stationary shaft 20. Pistons 78 and 80 are herein shown as hollow, spherical bodies whose outside diameter is only a few thousandths of aninchless than the inside diameter of the cylinders,so that the pistons are an extremely close fit withinthe cylinders. Close fit is necessary because there are no compression or oil scraper rings, as in conventional engines. It is not essential that the pistons 78, '80 be spherical, and that the respect to drive shaft 22, 26, is a crank pin 30, which is connected to the shaft by crank arms 32 and 34.

Within the housing 12 is a cylinder block 36 consist 1 ing of an assemblage of four individual cylinders 38, 40,

' one. Arm 52 has a bearing 56 which is joumaled on stationary shaft 20. Arm 52 also has an extension arm 58 extending radially away from shaft 20, and joumaled in a bearing 60 in the outeruend of arm 58 is afreerunning pinion 62: Pinion 6 2 meshes with a ring gear 64 that is pressed into a suitable seat formed in the top side of the'cylinder block 36, and also meshing with-the ring cylinders be circular in cross-section, as shown in the drawings, instead, the pistons might bemade in the form of cylinders having their axes parallel to the axis of the drive shaft, and with their length and diameters approximately equal, in which case the cylinders 38, 40, 42, 44 would be square in cross-section. Other configurations of pistons and cylinders could be used, but

minimize combustion blow-by. The use of piston rings is not feasible because of the rolling action of the pistons within the cylinders. There is no physical contact between the pistons andcylinders,and therefore no lubricating oil is required within the cylinder block,

although the bearings 24, 45, 56 and 60 are supplied with lubricant in the usual manner.

Centering of the pistons within their respective cylinders is accomplished by two means: (l precision gears 64, 66, which accurately synchronize the rotation of cylinder block 36 with its orbital movement about the axis 20, 22; and (2) turbulence of the air within the cylinder as the piston moves upwardly therein, which causes an equalized pressure to be exerted against the piston from all sides, causing the piston to center itself with respect to the cylinder.

Combustion blow-by may be further minimized by serrating either the pistons of the cylinders, or both, to provide roughened surfaces which create extremely high frictional resistance to the high velocity flow of combustion gases between them.

Projecting inwardly toward the shaft from the outer end of each piston is a protuberance 82, which has bored and tapped holes provided therein to receive a spark plug 84 and two fuel injector nozzles 86. The fuel injector nozzles have fuel lines 88 connected thereto, which pass through the hollow center of shaft 20 and are connected to a solid-state, electronic fuel injection pump 90, of the type currently used on the Volkswagen automobile engine. Ignition wires 92 are connected to the spark plugs 84, and these also pass through the hollow center of shaft 20, to an ignition system 94, which may be a conventional breaker-points type of system, or any of the solid-state electronic systems which are also available at this time. Spark plugs 84 are somewhat unconventional in the respect that they are screwed into the pistons from the outer ends of the latter, and the points of the spark plug are also exposed to the outer ends of the pistons. The terminal at the other end of the spark plug makes contact with a spring-loaded contact point 95 at the bottom of the cavity into which the spark plug is screwed, and contact point 95 is connected to the ignition wire 92.

The hollow center of stationary shaft 20 is also connected at 97 to blower 72 so that air from the latter is blown into each of the pistons 78, 80 to cool them. Outwardly directed, collar-shaped baffles 96 on the inner end of shaft 20 send the stream of cooling air into the hollow center of each of the pistons, where it circulates around and finally exits through discharge apertures 98 in the sides of the piston adjacent the point of connection to the shaft. This placement of the discharge apertures 98 causes the air leaving the pistons to be directed up into the cylinders as the pistons enter their respective cylinders, thereby scavenging any remaining exhaust gas and aiding in cooling the cylinders. The discharge apertures 98 are spaced angularly around the base of each piston and face toward the axis of the shaft 20, 22. The apertures are located about degrees in from a plane passing through the center of the piston perpendicular to an axis extending through the centers of both pistons. Thus, the discharge apertures 98 are located on the pistons 78, 80 so that as the piston first approaches a cylinder, the jet of air issuing from the aperture 98 on one side of the piston blows upwardly into the cylinder head 46 and down on the other side of the cylinder, as shown by the arrows in FIGS. 2-6, thereby scavenging any exhaust gases that may remain in the cylinder from the previous power stroke. As the cylinder block continues to rotate and orbit, the piston moves further up into the cylinder until at about the point shown in FIGS. 3 and 5, the escape of air from the cylinder is blocked by the piston, and a slight amount of supercharging takes place before the cylinder has rotated around the block to the aperture 98 and prevents any further discharge of air therefrom.

The mode of operation of the engine is as follows: Assume first that the engine is in the condition shown in FIG. 2. Piston 78 is at the top of cylinder 38, and the air that was trapped in the cylinder when the piston entered the cylinder and began the compression stroke is compressed to its maximum pressure. At this moment (or slightly before), fuel is injected through the nozzles 86 into the combustion chamber, and at the proper instant of time, the spark plug 84 is fired, causing the fuel charge to ignite. The arrows show the paths followed by the jets of air issuing from exit apertures 98.

In FIG. 3, cylinder 38 has just about completed its power stroke, and piston 80 has entered the bottom of cylinder 40. At this point, piston 80 has just closed the bottom end of the cylinder, and air trapped between piston 80 and cylinder head 46 is about to be compressed as cylinder 40 starts the beginning of its compression stroke. Piston 78 is just about to leave the bottom end of cylinder 38. It will be noted that (in FIG. 3) the flywheel 48 has advanced in the clockwise direction from its position in FIG. 2, whereas the cylinder block 36 has rotated only 45 in the clockwise direction. During the angular movement of the cylinder block 36 relative to the pistons 78, 80 in advancing from the position shown in FIG. 2 to that shown in FIG. 3, the jets of air issuing from apertures 98 in piston 80 have scoured cylinder 40 of any remaining exhaust gases, and in FIG. 3, the air leaving apertures 98 on one side of the piston is starting to supercharge the cylinder 40. However, the degree of supercharging is relatively small, especially at high engine speeds.

In FIG. 4, piston 78 has been withdrawn entirely from cylinder 38, and the combustion gases in cylinder 38 have been discharged into the interior of the cylinder block 36, from which they escape through apertures 74 and 76. Piston 80 is now at the top of cylinder 40, at which point fuel is injected into the combustion chamber and spark plug 84 fires to ignite the charge. The counterweight 48 and attached drive shaft 22 have advanced clockwise another 90 from the position shown in FIG. 3, and cylinder block 36 has advanced another 45. Jets of air issuing from exit apertures 98 in piston 78 blow lengthwise into cylinders 38 and 42, acting to scavenge exhaust gases from these cylinders.

In FIG. 5, piston 78 has entered the bottom of cylinder 42 to begin its compression stroke in that cylinder, while piston 80 moves downward from head 46 of cylinder 40 on the power stroke. counterweight 48 and drive shaft 22 have advanced clockwise another 90 from the position shown in FIG. 4, while cylinder block 36 has advanced 45.

In FIG. 6, the counterweight 48 and drive shaft 22 have completed one full revolution from the position shown in FIG. 2, while cylinder block 36 has completed a half-revolution. Piston 78 is now at the top of cylinder 42, having completed it compression stroke and being about to start its power stroke. Jets of air issuing from apertures 98 in piston 80 blow into cylinders 40 and 44 to scavenge exhaust gases from them.

sarily beconsiderably higher than in the spark-ignition engine. The fuel injected through nozzles 86 would be of the type suitable for Diesel engines, and the timing of fuel injection would be in accordance with accepted practice.

As mentioned earlier, the exhaust'ports 76 could be connected by a manifold to an efterburner (not shown) where additional fuel might be injectedand burned to completely oxidize any unburned fuel remaining in the exhaust gases. The exhaust from the afterbumer could then be directed against a turbine (not shown) to drive the latter, and the saidturbine could be connected by suitable gearing to the drive shaft .22 to provide additional power to the latter, or the turbine could be used to drive the blower 72.

While we have shown and described in considerable detail what we believe to be the preferred embodiment of the invention, it will be understood by those skilled in the art that theinvention is not limited to such details but might take various other forms.

We claim? s 1. An internal combustion engine comprising:

a stationary assemblageof n pistons;

an assemblage of Zn cylinders spaced equidistantly from one another in a radial arrangement;

a rotatable drive shaft having its axis of rotation concentric with the center of said assemblage of pistons, said drive shaft having an eccentric crank said cylinder assemblage being journaled for rotation about said crank pin and being supported for orbital movement about the axis of said drive shaft;

means for synchronizing the rotation of said cylinder assemblage with the orbital movement thereof,

whereby said cylinder assemblage rotates at onehalf the angular velocity of the orbital movement thereof, said orbital movement and said rotation being in the same direction; means for supplying air to the interior of said cylinder. assemblage and for exhausting combustion gases therefrom; each of said pistons being operable to enter one of two diametrically opposed cylinders with which it is associated, and to move relatively lengthwise therein toward thehead of said one cylinder, thereby. compressing the air contained within the cylinder;

means for injecting fuel into the compressed air when said piston .is at the top of its compression stroke, said fuel and air being ignited to initiate a power stroke, during which the piston moves relatively downwardly toward the bottom of said one cylinder;

said piston moving relatively out of said one cylinder and entering the cylinder diametrically across therefrom as said cylinder assemblage continues its rotational and orbital movement; and

means for cooling said piston.

2. An internal combustion engine as in claim 1, in which said piston assemblage is mounted on a stationary shaft coaxial with said drive'shaft, and said fuel injection means comprises injector no'z zlesmounted on the outer ends of said pistons, each of said injector nozzles being connected to a source of fuelunder pressure by a fuel line extendin alon said stationary shaft. An mterna com ustion engine as In cla m, 1,

which is further provided with spark plugs mounted in thef'outer ends of said pistons, said spark plugs being connected byignition wires to'an'electrical system for producing a timed spark at each plug when its associated piston is at the top'of its compression stroke,

said ignition wires passing along said stationary shaft.

4. An internal combustion engine asin claim 1, wherein said means for synchronizing the rotation of said cylinder assemblage with the orbital movement thereof comprises a stationary gear having its center located on the axis of said stationary shaft, and a ring gear fixed to said cylinder assemblage and rotating said cylinder assemblage, said engine having discharge openings through which combustion gases are exhausted. T

6. An internal combustion engine as in claim l, wherein said pistons are hollow, and means is provided for circulating coolant fluid through said hollow pistons. I I

7. An internal combustion engine as in claim. 5, wherein said piston assemblage is mounted on a hollow stationary shaft coaxial with said drive shaft, the interior of said hollow shaft being connected by a conduit to said blower, said pistons also being hollow, and the interior of the pistons being open to said hollow shaft, whereby cooling air discharged by said blower is circulated through said hollow pistons to cool the same.

8. An internal combustion engine asin claim 7, wherein said pistons have exit apertures. provided in the sides thereof, through which said cooling air is discharged in jets directed so as to blow up into the cylinders associated with that piston prior to entering. the same so as to scavenge any combustion gases remaining in the cylinder.

9. An internal combustion engine as in claim 7,

wherein said pistons have fuel injectors and spark plugs mounted in the outer ends thereof, said fuel injectors being connected by fuel lines to a source of fuel under pressure, said spark plugs being connected by ignition wires to an electrical system for producing a timed spark at each plug when its associated piston is at the top of its compression stroke, said ignition wires and said fuel lines passing through said hollow stationary shaft,

10. An internal combustion engineas in claim 1, in which there is a counterweight connected to said drive shaft to rotate therewith, said counterweight extending in the opposite direction from said crankpin and being shaped and proportioned to allow said cylinder assemblage to turn freely about the crankpin as it orbits about the axis of said drive shaft, said counterweight counterbalancing the mass of said cylinder assemblage which is centered on said crankpin.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3340853 *Apr 1, 1965Sep 12, 1967Edwin A LinkRotary piston engine
US3474954 *Feb 27, 1968Oct 28, 1969Rene Werner LinderRotary volumetric machine
US3514236 *Mar 13, 1968May 26, 1970Vish Machinno ElektrotechnitchRotary engine with epicyclic rotor
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5555853 *Mar 29, 1994Sep 17, 1996Bowen; Douglas M.Lightweight back-pack generator set having a spark-ignited engine operating on middle distillate fuels
US20050045841 *Aug 25, 2003Mar 3, 2005Hartman Delbert LeeTransverse disc motor
WO1995026464A1 *Mar 29, 1995Oct 5, 1995Libby CorporationLightweight back-pack generator set having a spark-ignited engine operating on middle distillate fuels
Classifications
U.S. Classification123/246, 418/99, 418/187, 418/151, 418/61.1, 418/91, 418/161
International ClassificationF02B75/02, F02B57/08, F02B1/04, F02B57/00, F02B1/00
Cooperative ClassificationF02B57/08, F02B2075/025, F02B1/04
European ClassificationF02B57/08