Stratified two-stroke engine and dual passage fuel system

Various embodiments include two-stroke stratified engines and dual passage carburetors for use with gaseous fuel, such as hydrogen, methane, liquid petroleum gas, pure propane, and butane. A stratified air-head engine and low pressure fuel injected engines with fuel only tube is included.

BACKGROUND

Conventional gasoline fueled four-stroke engine used in hand-held applications as in a trimmer and a blower sold by Ryobi and MTD and gaseous fueled blower by LEHR are environmentally friendly. However, the drawback is that those engines are very heavy and cannot be operated upside down for extended time and the same design cannot be used in chainsaws. Alternative two-stroke engines are advantageous, but very high in emission levels. Gaseous fueled two-stroke trimmer engine as manufactured and sold by Mitsubishi is a conventional two-stroke engine, which has significantly higher pollutants in the exhaust. Some conventional two-stroke engines sold in US have catalysts to lower the emission levels.

It is known in the engine industry that there are gaseous fueled two-stroke engines with oil injection system. However, these engines are conventional type which have high emission levels and the cleaner stratified engines are gasoline fueled and typically have oil pre-mixed with the gasoline. The disadvantage with gasoline fuel is that they smell bad when spilled and evaporate when stored for longer time. Secondly users have to always pre-mix oil for lubrication, which can harm the catalysts and as such emission levels may be bad toward the end of the life of the catalyst and or the engine. Thirdly, user may forget to mix oil with the gasoline which results in a scuffed engine.

The design described here has a gaseous fueled stratified two-stroke engine with a dual passage carburetor to lower the emissions and oil injection to lubricate the engine. The engine may further be fitted with catalysts to reduce the pollutants to even way below the legal limits. The gaseous fuel may be Butane, CNG, Methane, Hydrogen, or Propane or mixture of any gaseous fuels in any ratio. The engine can be used in many hand-held and lawn garden and mobile applications such as chainsaws, trimmers and scooters.

BRIEF SUMMARY

The new invention describes the designs of the new two-stroke engine and the carburetor for use with Gaseous fuel, like, H2, Methane, LPG, Pure propane, or Butane. The two-stroke engine is especially best for lawn and garden tools such as chainsaws, trimmers, blowers, pumps, and scooters.

The new invention reduces the emissions significantly with LPG or Butane as fuel and just water vapor and N2 and NOx when H2 is used.

Further, the inventions provide a new lubricating system where in the oil injection pump is driven by the crankshaft or belt or gear drive off of the crankshaft. Alternatively the oil pump may be a diaphragm pump with or without a plunger. The oil may be injected into the intake, particularly into the air-fuel mixture passage, or into the crankcase, and may also be injected into the transfer passage, particularly at the bottom of the passage in a stratified engine where air is drawn into the crankcase through the transfer passage. The gaseous fuel tank is attached to the bottom of the crankcase or at the top of the engine above the cylinder. The gaseous fuel tank may also be embedded inside the plastic housing on an engine, such as a chainsaw. There may be more than one fuel tank attached to the engine. The generator produced by Honda model EU9IGB has two LPG or Butane fuel canisters attached to the engine inside a plastic housing. A chainsaw which requires fuel to last longer, particularly when it is used on top of a tree, has advantage in having more than one fuel canister supplying fuel to the engine. Secondly an all attitude design for lubricating the engine would be advantageous, such having oil mixed in the air-fuel mixture.

Further the invention discloses a rotary valve controlled fuel injection system where the rotary valve opens and closes the crankcase port at the bottom end of the injection tube38. The rotary valve offers an un-symmetric port timings unlike a piston ported timing.

Further the invention discloses different dual passage gaseous fueled carburetors for independently regulating the air and air-fuel mixture. The secondary throttle body8902may be separate from the main throttle body401, while each of the bodies may have either rotary valve408or butter fly valve994bfor regulating the flow. Additionally the invention discloses where an external fuel tube220cconnects the metering chamber in the main body to the fuel orifice411bthrough a fuel passage220bin a secondary throttle body8902. Alternately the secondary throttle body8901may be integral part of the main throttle body401.

DETAILED DESCRIPTION

FIGS. 1, through6show new two-stroke gaseous fueled oil injected engines with special gaseous fueled carburetors having built in pressure regulator and metering chambers. The two-stroke engine are of stratified type having either a rich charge tube or air-head scavenging as described in U.S. Pat. Nos. 6,901,892, 4,253,433, and 6,273,037. The draw back in the prior arts are that the engines employ gasoline as fuel and oil has to be pre-mixed. The gaseous fuel two-stroke engine made by Mitsubishi as described in U.S. Pat. No. 5,918,574 is not a stratified engine, hence has significantly higher emission levels. The most commonly used gaseous fueled carburetors are not suitable for stratified engines. There are, however, gasoline fueled stratified carburetors, but they are not made to handle gaseous fuels. Therefore it is believed by the inventors that the inventions disclosed here would be beneficial to help the environment and reduce dependence on liquid fuels.

U.S. Pat. No. 6,901,892 for example describes a charge stratified engine inFIG. 1. The operating principle of the innovative engine100disclosed in this invention is similar to the engine10in the above reference. As such it will be understood by the person who has knowledge of engine will be in a position to execute the disclosed design. Engine100inFIG. 1consists of a cylinder12inside which is a reciprocating piston16connected to the crankshaft22through a connecting rod18, a crankpin20and a piston pin114. The crankshaft22has crank weight21and the crankshaft is supported by main bearings either on both ends of a full crank engine or just on one side in a half crank engine. The lower side of the piston has crankcase chamber26in the crank case28. The cylinder12has cylinder bore14having combustion chamber30on the upper side of the piston16. The crankcase chamber and combustion chamber are interconnected periodically through transfer passage11. The cylinder has at least one intake port84, exhaust port50, at least one transfer port33and an injection port40. The injection port40is connected intermittently to the crankcase chamber26. The lubricating system consists of a oil pump802driven by the crankshaft, typically mounted to the side of the crankcase wall. Oil pump802has an inlet oil line806and receives oil from oil tank808and has an outlet pipe803injecting oil into the intake passage310downstream of the lean valve80and possibly into the heat dam902.

The special gaseous carburetor400shown inFIGS. 2 and 3has at least two passages; a rich charge passage300and a lean charge passage310. The gaseous fuel carburetor has at least one pressure regulating chamber and a metering chamber317. The carburetor disclosed here has a high pressure fuel inlet620supplying fuel into a high pressure chamber517. In some embodiments, the construction of the high pressure chamber517receiving high pressure fuel at inlet620is to be constructed in accordance with the chamber shown inFIG. 5. High pressure chamber517has a diaphragm514and a high pressure needle valve513activated through a high pressure arm515. The diaphragm514has a spring542on the ambient side of the diaphragm and the spring and the diaphragm are held in place by the high pressure chamber cover540. The ambient side of the diaphragm is at ambient pressure. The high pressure chamber517is connected to a low pressure chamber417through a high pressure fuel passage520. Similar to the high pressure chamber517, the low pressure chamber has a low pressure needle valve413, diaphragm414, arm415, a spring442and a cover440. The low pressure chamber417is connected to a metering chamber317through a low pressure fuel passage420. The metering chamber also has a metering chamber needle valve313activated by the metering chamber arm315. The metering chamber diaphragm is pushed outward by a metering chamber spring342, which also acts against the metering chamber needle valve313to keep the fuel flowing from low pressure chamber417to the metering chamber317when the engine is not running and when the pressure across the metering chamber diaphragm314is same is zero, that is; the pressure in the metering chamber317is same as ambient. Fuel can flow into the metering chamber317only when the pressure in the chamber317is sub atmospheric and thus preventing any fuel leak into the intake passage when the engine is dead.

When the engine is running, the sub atmospheric pressure intake passages406and300is sub-atmospheric, the pressure in the metering chamber317also drops to sub atmospheric causing the diaphragm to move inward against the spring342, thus opening the needle valve313to open. The metering chamber has lean fuel passage320to the lean passage310opening at the fuel orifice410, preferably at the venture406and may have more than one orifice as described in gasoline carburetors in the prior arts. The metering chamber317also has a rich fuel passage220supplying fuel to the rich passage300through the fuel orifice411. The fuel flow to the fuel passages320and220are adjustable through the respective screws408and407.

As the pressure in the metering chamber317drops, the metering needle valve313is lifted off its seat letting the fuel to flow in from the low pressure chamber417through the passage420. In turn, when the pressure in the low pressure chamber417drops, the low pressure needle valve413is lifted off its seat, because the needle413is activated by the low pressure arm415attached to the low pressure diaphragm414, which is pushed downward by the low pressure spring442. The diaphragm414and the low pressure spring is held in place by the low pressure chamber cover440. When the pressure in the low pressure chamber417drops, the low pressure needle valve413opens and the fuel flows from the high pressure chamber517to the low pressure chamber417through the high pressure passage520. The drop in pressure in the high pressure chamber517causes the high pressure diaphragm514to move downward thus the high pressure needle valve513is lifted off its seat letting the high pressure fuel to flow from the high pressure fuel tank700through the fuel inlet620. As described, the pressure drops in stages from high pressure to the almost atmospheric in the metering chamber317. The gaseous fuel stored in a propane or butane tank700, for example in a Coleman's propane fuel tank is at about 100 psi or a Butane fuel tank commonly used by Mitsubishi's trimmer engine is at a lower pressure.

The gaseous carburetor400has a rich charge passage300supplying rich charge (rich fuel-air mixture) into the injection tube38, through a one way valve36in the intake heat dam902. As described in prior art, U.S. Pat. Nos. 6,901,892 and 6,293,235. The lean passage310supplies lean charge (lean fuel-air mixture) with oil into the crankcase chamber26. The intake and scavenging process is explained in detail in the prior arts U.S. Pat. No. 6,901,892 and others. It is to be known that person skilled in the art understands the operating principle by reading the prior arts U.S. Pat. Nos. 6,901,892 and 6,293,235 in its entirety. However, in this invention, the oil is injected into lean charge in the lean passage310, preferably at the intake heat dam902. The flow of rich and the lean charge into the engine are regulated by the respective control valves81and80. Both the valves81and80are mounted on to a common throttle shaft479. However, they may be mounted on separate throttle shafts linked to each other and may be at phase with each other. Also, in the disclosure, the undercut (or a through hole) in the throttle shaft479in the rich charge passage may act as a throttle valve81and not have a separate valve. It must be understood that the dual valves may be of any type; butterfly valve, rotary valve also known as barrel valves, or slide valve, which are commonly known to the person skilled in the art. The passages of the carburetors400and8400may be one piece or may be two separate bodies.

Further the invention discloses a dual passage carburetor8400for air-head stratified engines. Prior arts U.S. Pat. Nos. 6,901,892 and 6,112,708 describe in detail the operating principle of a air-head stratified engine. Engine200inFIG. 4consists of a cylinder2012inside which is a reciprocating piston2016connected to the crankshaft22through a connecting rod18, a crankpin20and a piston pin114. The crankshaft22has crank weight21and the crankshaft is supported by main bearings either on both ends of a full crank engine or just on one side in a half crank engine. The lower side of the piston has crankcase chamber26in the crank case28. The cylinder2012has cylinder bore14having combustion chamber30on the upper side of the piston2016. The crankcase chamber26and combustion chamber30are interconnected periodically through transfer passage11and transfer port33. The cylinder2012has at least one intake port84for air-fuel mixture, at least one air inlet port, exhaust port50, and at least one transfer port33. The engine operates like a conventional two-stroke engine. First and second piston ports99and101are disposed on the skirt2113of the piston2016and are connected to each other in gaseous communication by air channel96. The complete description of the air-head engine is described in entirety in the U.S. Pat. No. 6,901,892. The lubricating system consists of a oil pump802driven by the crankshaft, typically mounted to the side of the crankcase wall. Oil pump802has an inlet oil line806and receives oil from oil tank808and has outlet pipe803injecting oil into the intake passage310downstream of the lean valve80and possibly into the heat dam904. The engine200described is referred to as a piston ported air-head engine. It must be understood that the air-head stratified engine may also be a reed valve air-head stratified engine, where in the air is inducted into the transfer passage11through a reed valve (also known as one-way valve) as described in U.S. Pat. No. 6,901,892 inFIG. 31. However, it is optional to have rotary valve open and close the opening of the transfer passage in the crankcase chamber.

Further, the dual passage gaseous carburetor8400shown inFIGS. 5 and 6have common pressure regulating and metering parts as described with respect to carburetor400. As such description and operating principle will not be repeated. However, the main difference between the carburetor400and8400is that in carburetor8400, only the air-fuel passage8300is supplied with the gaseous fuel through a fuel passage8320from the fuel metering passage317, whereas, the air passage8310supplies only air into the transfer passages. Air-fuel mixture and air are regulated by the respective air-fuel valve881and air valve94respectively. Fuel is adjusted with the fuel adjusting screw408. The oil is injected into the air-fuel passage8300at downstream of the air-fuel valve881through an oil injector. The oil may also be injected directly into the crankcase chamber26through the side wall of the crankcase28or may also be injected through a central hole in the crankshaft22and through a cross drilled hole in the counter weight (not shown). When injected directly into crankcase chamber or through crankshaft, it eliminates the need for oil feed line803. Also, the oil tank may be attached to the side of the crankcase on the outside between the starter housing and the crankcase outer wall. It must be understood that the carburetors400and8400may be combined to form a three-way carburetor as described in U.S. Pat. No. 6,901,892 and shown inFIG. 7, however, it will be a gaseous fuel with oil injection into lean charge passage. Also, the control valves may be of any type; butterfly valve, barrel or rotary valve, or slide valve.

It is also possible for rich fuel to be inducted into the injection tube38and the opening into the crankcase chamber26be periodically opened and closed by the cut out on the counter weight21, as described in the prior art U.S. Pat. No. 6,901,892. Also, it is possible that the pure air with or without oil injected into the air be inducted into the crankcase chamber26through transfer ports33as in the air-head engine described in U.S. Pat. No. 6,901,892, where as the air inlet is through a one way valve or through the air channel in the piston as described in U.S. Pat. No. 6,901,892.

FurtherFIG. 7shows a three way carburetor9009, in which there are three barrel valves94,81, and80are respectively control only air, rich charge, and lean charge. The three valves are mounted on a rotatable barrel valve body803in a gaseous fuel carburetor body801. The operating principle of the gaseous carburetor8900is similar to the carburetor8800. The valve94regulates only the air, valve81regulates a rich air-fuel mixtures, and the valve80regulates lean air-fuel mixtures to the engine.

FIG. 8shows details of the fuel jet9423and the regulating fuel needle9407. It shows that the fuel needle9407having a tapered tip430. As the fuel needle9407slides upward the effective flow area for the fuel increases. The fuel jet9423also has lateral holes that supply fuel to the lean air-fuel mixture in passage406. U.S. Pat. No. 6,901,892 describes in details a three way liquid fuel carburetor which does not have pressure regulator as described in this embodiment.

The air fuel mixture (or air) could be regulated by a rotary valve. Alternatively, the air passage8310bcould be regulated by a butterfly valve, where the two valves are connected by some kind of linkage. Similarly, the air fuel mixture passage could be regulated by a butterfly valve, with the air passage regulated by a rotary valve. In this case too, the valves could be connected by a linkage.

The two-way carburetor8800is illustrated in more detail inFIG. 9and the engine is illustrated in detail inFIG. 4. As the piston2113ascends in the cylinder bore14of the engine, the pressure in the crankcase chamber26drops below ambient. The differential pressure between the crankcase chamber26and the ambient (outside of the carburetor) causes air to flow into the crankcase chamber26through the appropriate passages (transfer passages or charge passages). There are two flow transversely extending venturi passages in a longitudinally extending barrel423of a two-way carburetor. An air venturi passage404ballows only air, which is regulated by the air control barrel (rotary) valve94, to flow into the transfer passage11. A charge venturi passage405flows air-fuel mixture regulated by a charge barrel (rotary) valve81into the charge passage406directly into the crankcase chamber26. The air control and charge barrel valves are mounted on a rotatable barrel (rotary) valve body403in a gaseous carburetor body401having at least one pressure regulating chamber517and a metering chamber317, having a fuel passage320feeding fuel from metering chamber317into the passage9300(405).

Further, the dual passage gaseous carburetor8800shown inFIG. 9has a pressure regulating and metering parts as described with respect to carburetor8400, shown inFIG. 6. As such description and operating principle will not be repeated. However, the main difference between the carburetor8800and8400is that in carburetor8800, the regulating valves for only air and for air-fuel mixtures are the rotary barrel valves94and81respectively are on a single barrel valve body423. Also, it should further be noted that there is at least one pressure regulating chamber517connected to the metering chamber417through a passage527. The passage320is in the form of a tube extending through the barrel valve body (423) and opening into the air-fuel charge venture passage405(9300). The fuel tube320in this carburetor8800extends slightly into the metering chamber417. The amount of fuel is regulated by a needle valve9407having a tapered end430at the lower tip of the needle9407. Alternately, the fuel tube320may have a slot or opening at the upper tip in triangular shape, while the regulating needle is cylindrical in shape. As the needle9407is sliding up and down as the barrel valve body403is rotated, the amount of fuel is also varied. The barrel valve body403is resting on a wedge (ramp)425and the top of the barrel valve body403has a flat disc408having a ramp on the lower surface. Thus as the valve body403is rotated, the ramp on the wedge forces the valve body403to rise as well, which in turn rises the fuel control needle9407. The tapered shape of the needle in the fuel tube320varies the flow area for the fuel. Thus the fuel and air are concurrently varied.

The pressure regulating chamber517and metering chamber417are integral to the barrel valve carburetor body401.

FIG. 9bshows where the air throttle body801cand the air-fuel throttle body801(401) are two separate bodies stacked up such that the rotary barrel valves479aand barrel valve479bare concentric and one is on top of the other and the bodies801and801care fastened together with a gasket803sandwiched between the two bodies. The rotary valves for air479band479aare two separate pieces, but acting as a single piece because of the coupling805. However, the rotary valve can be a single piece as shown inFIG. 9. The advantage is that the air-fuel throttle body can be common to dual passage carburetor and also a single passage carburetor. As such no separate tooling is necessary to make two separate throttle bodies for the use of carburetors on conventional and stratified two-stroke engines.FIG. 9cshow cross sectional view of the air throttle body having a single inlet passage8310bfor air, but having dual outlets8310cand8310d. The advantage with dual outlet passage system is that the manifold904cused in stratified engine360can be exactly similar to the manifold of a conventional non-stratified two-stroke engine and does not have to be a complex type manifold as disclosed in a prior art, U.S. Pat. No. 6,112,708. The advantage of stacked up dual passage throttle bodies is that the air-fuel throttle body801may be used for both conventional and stratified two-stroke engines. With the dual outlet air throttle body, conventional manifold as used with a single passage carburetor may be used without having to retool for a new manifold.

FIG. 10shows the a dual passage gaseous fueled carburetor8900having a rotary barrel valve81for the regulation air-fuel mixture in a similar way explained for the dual passage gaseous carburetor8800shown inFIG. 9. However, valve for regulating the air only passage is now a butterfly valve994b, in a separate body8902, interconnected by a linkage9408bto the flat disc408on the barrel valve body403. The body8901of the butter fly valve994bcould be rigidly mounted to the gaseous fuel barrel valve carburetor body401through a rigid body9409b.FIGS. 10band10cshow two types of throttle bodies for the air control. InFIG. 10b, the air passage8310bin the body8902is divided into two separate passages8310cand8310d, each connected to the air pipe88to supply air into the transfer passages11on either side of the exhaust port50. Whereas, inFIG. 10c, the single air passage8310bis exiting the throttle body8902. Advantage with single exit air passage is that an integral air pipe87(shown inFIG. 21) can be used to supply air to the left and right transfer passages. Whereas with dual exits air throttle body, two separate air pipes (left and right) are used. Secondly a simple manifold904may is used in both the types of air throttle bodies disclosed inFIGS. 20 and 21. The manifold904shown inFIG. 20is similar to the type used in a conventional two-stroke engine, where the intake system does not have additional air supply system (commonly used in stratified engine). The manifold (suction fitting4) disclosed in the prior art U.S. Pat. No. 6,112,708, is a complex and larger in size. However, the functionality of the manifold (suction fitting) described in the prior art can easily be integral with the throttle body (8902) itself as disclosed in this new embodiment. The advantage is that the manifold need not be retooled nor be as complex, while the throttle body8902can be cast either as a single exit and dual exits for easy manufacturing and assembly.FIG. 11shows a dual passage carburetor8910having a separate secondary throttle body8902attached to the main throttle body by means of a member9409b. The secondary throttle body8902has a valve994b, which can be a butter fly valve, rotary valve, slide valve or a simple shaft (or tubular) valve having a slot as shown inFIG. 2. The secondary throttle body regulates either just the fuel only or air-fuel mixture into the injection tube38in a stratified charged engine. The secondary throttle body8902has a fuel passage220breceiving fuel from the metering chamber317in the main throttle body401through an external fuel tube220c. The main throttle body401(479) has a rotary valve81to regulate air-fuel mixture as shown inFIGS. 11andFIG. 12. Where as in aFIG. 13, the main throttle body has valve423to regulate only air and the main venture (passage)8310is not does not receive fuel. The regulating valve423may be of sliding valve as used in conventional gaseous fueled carburetors, or rotary barrel valve as shown inFIG. 13, or a butter fly valve as shown inFIG. 3.

FIG. 14shows top view of the dual passage carburetor, where the throttle actuating assembly9408consists of lever9408battached to the secondary valve994band a lever9408aattached to the throttle valve disk408in the main throttle body401. The throttle actuating levers9408band9408aare in contact with each other and have spring load on each to bring to the normally closed position. The two valves operate in conjunction with each other. A delay in actuating one or the other may be achieved by providing a gap between the two in valve closed position. That is; air control valve81may be opened later after the air-fuel valve994bis open from idle to say about 25% of throttle opening. The delay may be desirable for smoother starting and stable idle speed as well as acceleration.

FIG. 15shows a stratified engine150similar to the stratified engine100shown inFIG. 1. However, inFIG. 15, the lower end of the injection tube38is open directly into the crankcase chamber26through a crankcase port41, which is opened and closed by a cut on the crank web, which is a rotary valve, opening and closing the crankcase port41per pre-determined timing in respect to upward and downward stroke of the piston. The detailed description of the operation of the rotary shut off valve is explained in the prior art U.S. Pat. No. 6,901,892. The engine

FIG. 16shows a fuel system7000having a pressure regulating system6000consisting of multiple stage pressure regulating chambers, as shown inFIG. 2, but having an air only regulating valve81. The fuel system7000also has a separate fuel regulating system5000having air-fuel (or fuel only) regulating valve881b. The operating principle of the multiple stage pressure regulating body is similar to the carburetor shown inFIG. 2and explained earlier. However, it must be noted that the pressure regulating system6000does not supply fuel to the air passage8310in the pressure regulating body401, unlike the carburetor shown inFIG. 2. The embodiment clearly shows a separate fuel regulating system5000, detached from the pressure regulating system7000for regulating the fuel. However, the two systems may be attached to one another through a mounting bracket9409cand fasteners9409b. The fuel regulating system has a body8902having a regulating valve881b, which can be one of many types, such as rotary, butterfly or sliding valve. The body8902has fuel passage200bhaving at least one fuel orifice411bopening into the venture406. The air-fuel (or fuel only) is regulated by the regulating valve881bdepending on the operating condition of the engine. The pressure regulating6000system has a body401having a rotary valve423as shown inFIG. 16for regulating only the air, required for an air-head (stratified) engine. In theFIG. 16, the air regulating valve423is of a rotary valve type (it can be a butterfly or sliding valve type), having a ramp or a cam425to operate the valve881bthrough linkage9408. As such as the rotary valve rotates to regulate the flow of air through the passage8310, the valve881bis also rotated appropriately. The fuel regulating system5000has a venturi406having at least one fuel orifice411b. The fuel regulating body8902receives fuel from the pressure regulating body6000through at least one fuel passage220having a fuel adjusting valve407having a tapered end and the fuel tube220dhaving a tapered seat407b. The fuel tube220dis connected to the fuel regulating system5000through a flexible hose220cconnecting the internal fuel passage220bin the fuel regulating body8902. The air only regulating valve423in the pressure regulating body401has a ramp (cam)425which activates the valve881bas the regulating valve423is operated. Thus the air only valve423and air-fuel (or fuel only) valve881bare actuated simultaneously as the operator actuates the throttle to change engine speed.

The advantages of the separate systems6000and5000are that the two systems may be mounted part from each other that consistent with the engine architecture. Some two-stroke engines may have reed valved or rotary valved main intake port (not shown) for air-fuel charge located on the crankcase28, while the air only intake port may be on the cylinder block supplying air into the transfer passage, as shown inFIGS. 4 and 4b. Another advantage is that the air-fuel (or fuel only) regulating body8902may be completely isolated from a heavier pressure regulating body403, from the heat and vibration point of view, because the fuel supply line220cis a flexible pipe, when the system5000is not attached to the system6000.

FIG. 17shows a fuel regulating system7600without any flow controlling valve. As such the system6600which is identical to system6000and system shown inFIG. 2from the pressure regulating point of view is simply a body401bhaving multiple pressure regulating chambers, which can be mounted remotely away from the intake port of an engine. The air-fuel controlling system5600, however, has a flow controlling valve881cto meter the air and fuel mixture into the intake port of an engine. The air-fuel metering system5600has a body8902bwith the passage8300b, at least one fuel orifice411b. The fuel is supplied from the pressure regulating system6600to the system5600through a flexible fuel supply line220c, which again isolates the air-fuel regulating system5600from the pressure regulating body401b. Therefore, the pressure regulating system7600can be mounted remotely and separately from the system5600.

FIG. 18shows a system7000having a pressure regulating system6600and a separate dual passage for air only and air-fuel (or fuel only) metering system5700. The system5700has two separate valves94and881bin a single body8902b(or could be separate bodies, not shown) to regulate the air and air-fuel respectively. The systems600and5700are mounted separately to isolate any kind of vibration and heat or can be attached to each other as convenient. Again, the fuel supply from the pressure regulating body6000to the system5700is through a flexible fuel supply line200cand the fuel supply has a rich fuel adjusting screw407. The body8902bhas internal fuel passage220band at least one orifice411bin the venture8300b. The valve94for controlling the air and valve881bfor controlling air-fuel (or fuel only) are linked to each other so they are operated simultaneously (with some delay in opening the air-only valve, as necessary). It must be noted that the flow controlling valves may be a combination of any type of valves; rotary, butterfly, or sliding (barrel) valves. They may be interlinked directly or indirectly through linkages or cables, or gears. They could even be mounted on a common shaft as shown inFIG. 2andFIG. 9. The inter connecting passages between the chambers in a multi-stage (chambered) pressure regulating system shown in the embodiments disclosed here are only an example and may be inter connected through external pipes as well. Also, the pressure regulating springs, example542may be inside the body401, while the arm515, needle527may be on the chamber cover540. Also, the pressure regulating spring542may have a pressure adjusting screw to set the pressure, which is a common practice in any pressure regulating devices, commonly used in welding gases.

Another embodiment of this disclosure is that the pressure regulating system with or without the controlling valves, can be made of moldable material, such as delrin, which is cost effective to manufacture the body. Also, in order to improve the sealing between the needle513and the seat in the body, metal of appropriate material can be inserted later or insert molded for integrity. The needle, when long enough to be guided inside the valve seat, may account for any deformation due to heat of molding error. Another advantage of having a remote or separate pressure regulating body is that the body401can be integrally cast with the engine block or the crankcase28in an engine, while the flow regulating valves can be attached to the intake port/passages of an engine.

FIG. 19shows an air-head stratified engine350having air pipe88for supply of air from atmosphere into the transfer passages11through the reed valve (check valve or one-way valve). The air pipe is connected to the manifold904bhaving which is connected to the carburetor8400(7000), which has an air throttle body for regulating the air. As the piston2316moves upward, it closes the exhaust port50and then the transfer port33. Further upward stroke creates more vacuum forcing the check valve89to open and thus drawing atmospheric air into the transfer passage11. Further upward stroke of the piston2016causes the piston skirt2113to uncover the intake port84to open and thus air-fuel mixture is drawn into the crankcase. The oil may be injected into the intake passage8300for lubricating the internal parts of the engine. The oil pump802is driven by the crankshaft22. The operating principle of the air-head or the stratified engine is similar to the one described in prior arts. As the piston starts to move downward, the pressure in the crankcase chamber26exceeds the atmospheric pressure or the pressure in the manifold, thus forcing the reed valve89to close. Further downward stroke of the piston2016closes the intake port84. Thus the crankcase pressure increases. As the piston continues the downward stroke, it uncovers the exhaust port50first and followed by the transfer ports33. As the crankcase pressure is higher than the combustion chamber pressure, past the blow down phase, the air in the transfer passage11enters the combustion chamber first, followed by the air-fuel mixture. Thus the air that enters first is the one that gets short circuited and therefore emission is lower and fuel consumption is better than a conventional engine. Oil is injected in a non-pre-mixed fuel or in a gaseous fueled two-stroke engine.

Engine360shown inFIG. 20is identical to the engine350shown inFIG. 19, except that the intake manifold (or sometimes called heat dam) is different. InFIG. 20, the manifold904cis similar to the one used in a conventional two-stroke engines, unlike the one disclosed in prior art U.S. Pat. No. 6,112,708. That is, the manifold has only one passage for the air-fuel mixture. However, in this embodiment, the air pipe88is directly connected to the air-throttle body8902either having dual exit, as shown inFIG. 9candFIG. 10b. Alternatively the air throttle body may have a single exit air passage8310bas shown inFIG. 10, while the air pipe87will be a single piece pipe having a common inlet at86and diverging into two separate pipes89′ and89″ to supply air into transfer passages11on either side of the exhaust port50as shown inFIG. 21. The air-head stratified engine350shown inFIG. 21shows the reed assembly2089and reed valve89. The reed assembly is connected to the air pipe87and the common inlet at86is connected to the single exit air throttle body8902.

In various embodiments, pipe87is a single U-shaped unit. The pipe may receive inflow at the base of the ‘U’, and such flow may then branch off at86into the two sides of the ‘U’ at88. Embodiments where pipe87is a single unit provide advantages in construction and complexity over alternatives that would involve two or more separate components to accomplish the same function.

In various embodiments, pipe87has a generally rounded construction. Thus, flows are not required to turn around sharp corners, and smoother flow progression is accomplished.

The following are embodiments, not claims:A. A gaseous fueled dual passage carburetor400comprising:a. a lean passage310;b. a lean valve80;c. a rich charge passage300;d. a rich valve81;e. at least one pressure regulating chamber with a diaphragm, spring, and a needle valve;f. a first fuel passage320leading into the lean passage310; a second fuel passage220leading into the rich charge passage300;g. a fuel tank (850);h. a gaseous fuel inlet (620) receiving fuel from the fuel tank (850);i. a venture (406);j. a first fuel orifice (410) in the venture (406); andk. a second fuel orifice (411) in the rich charge passage (300).B. The carburetor (400) of embodiment A in which the both the lean valve80and rich valve81are control valves.C. The carburetor (400) of embodiment B in which control valves80and81are on one shaft (479).D. The carburetor (400) of embodiment C in which control valves80and81are each butterfly valves, and are each cut out on the shaft (479).E. The carburetor (400) of embodiment A in which the both the lean valve80and rich valve81are rotary valves.F. The carburetor (400) of embodiment A in which the lean valve80is a butterfly valve and the rich valve81is a rotary valve.G. The carburetor (400) of embodiment A further including three mounting holes402,403, and404.H. The carburetor400of embodiment A, in which the carburetor is embedded within an engine, the engine including a crankshaft106, an attached LPG or Butane fuel tank, and a separate oil tank140shaped such as to access oil at all engine attitudes, the carburetor400further comprising:a. an oil injector702for injecting oil into the passage310; andb. an oil injection pump138driven by the crankshaft106.I. The carburetor (400) of embodiment A further comprising an internal combustion engine.J. A gaseous fueled two-stroke engine100having a gaseous carburetor400with an oil injection pump138driven by a crankshaft106with an LPG or Butane fuel tank attached to the engine and a separate oil tank140shaped such as to access oil at all engine attitudes.K. The engine of embodiment10having a cylindrical fuel tank.L. The engine200of embodiment10having at least one air inlet port98, at least one air channel96, at least one first piston port99, at least one second piston port99, a transfer passage11, a transfer port33, an exhaust port50, and a piston2016reciprocating in the cylinder2012.M. An internal combustion engine comprising:i. a cylinder (12);ii. a cylinder bore (14);iii. a crankshaft (22);iv. a piston (16) connected to the crankshaft (22) having a counter weight (21);v. a crankcase chamber (26);vi. a combustion chamber (30);vii. at least one injection port (40) intermittently open to the combustion chamber (30);viii. an injection tube (38) intermittently filled with gaseous fuel, and intermittently connected to the crankcase chamber (26);ix. a oil injection pump (802) driven by the crankshaft (22);x. a oil tank (140);xi. at least one intake port (84);xii. at least one exhaust port (50); andxiii. an oil injector (702),xiv. in which the gaseous fuel is significantly free of oil.N. The engine of embodiment M further comprising an injection tube (38) intermittently filled with air and fuel.O. The engine of embodiment M in which the injection tube (38) is intermittently filled with fuel only.P. The engine of embodiment M, in which the piston makes repeated cycles, and in which, on each cycle the injection tube (38) is filled with gaseous fuel only, which is added to residual gas remaining from a previous cycle.Q. The engine of embodiment M further comprising an intake port (84) intermittently supplying only air into crankcase chamber (26).R. The engine of embodiment M in which oil is injected into intake air.S. The engine of embodiment M in which oil is injected into air-fuel mixture.T. The engine of embodiment M, further comprising a transfer passage, in which oil is injected into the transfer passage.U. The engine of embodiment M in which oil is injected into crankcase chamber (26) through a passage in crankshaft (22).V. The engine of embodiment M further comprising a heat dam (904) in which oil is injected into the heat dam (904).W. An internal combustion two-stroke engine (200) comprising:i. a cylinder (2012) and a cylinder bore (14);ii. a crankshaft (22) having a counter weight (21);iii. a piston (2016) connected to the crankshaft (22),iv. in which the piston has a piston skirt (2113) and at least one air channel (96) on the piston skirt (2113);v. at least one first port (99) and at least one second port (101), the first and second ports intermittently aligning with at least one air inlet port98and at least one transfer port33, respectively;vi. a crankcase chamber (26),vii. an oil injection pump (802) driven by the crankshaft (22);viii. an oil tank (140);ix. at least one exhaust port (50);x. an oil injector (702);xi. at least one intake port (84), in which a gaseous fuel is inducted through intake port (84) and oil is injected into crankcase chamber26through intake port84;xii. and a dual passage gaseous carburetor (8400).X. The engine of embodiment W further comprising a gaseous fuel tank (850).Y. The engine of embodiment W in which the oil tank is separated from the engine.Z. An internal combustion engine comprising:i. a cylinder (2012) and a cylinder bore (14);ii. a crankshaft (22) having a counter weight (21);iii. a piston (2016) connected to the crankshaft (22),iv. in which the piston (2016) has at least one air channel (96) on the piston skirt (2113);v. at least one air inlet port (98);vi. at least one transfer port (33);vii. at least one first port (99) and at least one second port (101), in which the first and second ports intermittently align with the at least one air inlet port (98) and the at least one transfer port (33), respectively;viii. a crankcase chamber (26) receiving intermittent injections of oil;ix. a combustion chamber (30);x. at least one injection port (40) intermittently open to the combustion chamber (30);xi. a injection tube (38), the injection tube (38) intermittently filled with gaseous fuel that is significantly free of oil; and intermittently connected to the crankcase chamber (26);xii. an oil injection pump (802) driven by the crankshaft (22);xiii. an oil tank (140);xiv. at least one first piston port (99);xv. at least one second port (101); andxvi. at least one exhaust port (50).AA. A gaseous fueled carburetor comprising:a. at least one pressure regulator;b. at least one metering chamber;c. a first valve for air-fuel regulation;d. a second valve for air only; ande. a linkage between the two valves.BB. The carburetor of embodiment AA in which the first valve is a rotary valve and the second valve is a butterfly valve.CC. The carburetor of embodiment AA in which the first valve is a butterfly valve and the second valve is a rotary valve.DD. A gaseous fueled dual passage carburetor8400comprising:a. an air passage8310and air-fuel passage8300, with each passage controlled by respective control valves94and881;b. at least one pressure regulating chamber which includes a diaphragm, spring, and needle valve;c. a fuel metering chamber317operable to supply fuel into the air-fuel passage8300at sub atmospheric pressure.EE. A gaseous fueled carburetor8900having:a barrel valve81for regulating the air-fuel mixture;at least one butter fly valve994bfor regulating the air,butterfly valve99band barrel valve81inter connected by means of a linkage9408b, having at least one pressure regulating chamber517,at least one metering chamber317FF. A gaseous fueled carburetor8900having:a barrel valve81for regulating the air-fuel mixture;at least one butter fly valve994bfor regulating the air,butterfly valve99band barrel valve81inter connected by means of a linkage9408b, having at least one pressure regulating chamber517,at least one metering chamber317,barrel valve body having at least one mounting hole402(and403), and;butterfly valve body8901having at least one mounting hole404.GG. A stratified engine having a check valve at the top of the transfer passage and having single air pipe87diverging into two air pipes89′ and89″ to supply air from a single exit air throttle body8902to the transfer passages11. Engine360having a simple manifold (heat dam) commonly used with catalyzed two-stroke engine and not being a stratified engine. Carburetor being either a gaseous fuel or liquid fuel.HH. A dual passage (gaseous or liquid) carburetor for a stratified engine having a air throttle body8902having dual exits for supply of air to the transfer passages11located on either sides of the exhaust port50.

Various embodiments include a carburetor that advantageously has a built-in pressure regulating chamber, because fuel supplied to carburetor is already under pressure. Various embodiments utilize a fuel compressing liquefied petroleum gas. In some embodiments, the fuel could be natural gas, hydrogen gas, or any type of fuel essentially free of oil.

Parts List

It is to be understood that other modifications of the invention shall be apparent to those skilled in the art from the teachings herein and, it is, therefore, desired to be secured in the appended claims all such modifications as fall within the true spirit and scope of the invention.