Patent Publication Number: US-6907850-B2

Title: Internal combustion engine and method of enhancing engine performance

Description:
This invention pertains to an apparatus and method to enhance the overall performance of engines (e.g., diesel and gasoline-fueled internal combustion engines) in one or more of the following ways: by reducing engine wear; by increasing the power output; or by reducing the level of unwanted atmospheric emissions. 
   Emission problems for engines (e.g., 2-stroke and 4-stroke internal combustion engines) are a major environmental and public health concern. For example, studies have shown that conventional marine engines (outboard and personal watercraft engines) contribute about 12% of the total hydrocarbon or atmospheric pollutants (“HC”) emitted into the atmosphere by mobile sources. In 1998, the Environmental Protection Agency (“EPA”) established stringent HC emission standards for marine engines to be implemented over a nine year period. The new standards require that all manufacturers of outboard and personal watercraft engines produce engines with 75% lower HC emissions by 2006. See United States Environmental Protection Agency—Air and Radiation—Office of Transportation and Air Quality, “Reducing Air Pollution from Non-road Vehicles,” EPA420-F-00-048, November 2000. 
   While 4-stroke internal-combustion engines (“4-stroke engines”) generally produce lower HC emissions than 2-stroke internal-combustion engines (“2-stroke engine”), conventional marine engines are preferably 2-stroke engines because of the reduced weight, construction simplicity, and higher power output. The functional difference between conventional 2-stroke and 4-stroke engines is in the number of piston strokes required to complete a power cycle, i.e., to intake a mixture of fuel and air (“intake stroke”), compress and ignite the mixture to produce a “power stroke,” then exhaust the combusted gases (“exhaust stroke”). Most engines have a crankshaft, combustion chamber, piston and connecting rod. In a conventional 2-stroke engine, significant quantities of unburned fuel (approximately 25-30%) bypass the combustion chamber and escape to the atmosphere, because a single stroke is used to exhaust combusted gases and recharge the combustion chamber for the next power stroke. More specifically, in 2-stroke engines, the air-fuel mixture enters the combustion chamber through inlet ports during the intake stroke. The piston then compresses the mixture until it is ignited by a spark plug, producing the power stroke. (In the case of a diesel-fueled internal combustion engine, ignition will occur when the diesel fuel is injected into the combustion chamber and comes into contact with superheated air.) As the piston retracts, an exhaust port is opened and combusted fuel exits the combustion chamber. While the combusted fuel exits the combustion chamber, a new air-fuel mixture is loaded into the combustion chamber through inlet ports. Each time a new air-fuel mixture is loaded, a portion of it exits with the combusted fuel. Furthermore, most 2-stroke marine engines use a scavenging system in which the air-fuel mixture is loaded into the crankcase, compressed in the crankcase, and then routed from the crankcase to the combustion chamber as the piston retracts into the crankcase. Mists of lubricating oil from the crankcase mix with the air-fuel mixture as it is loaded into the combustion chamber. This increases the amount of lubricating oil contained in the combustion chamber, which increases the amount of HC and other components that exit with the combusted fuel, including raw fuel. See U.S. Pat. No. 5,732,548; and European Patent Application No. 1,039,113. 
   U.S. Pat. No. 6,209,495 describes a compound two stroke engine that uses two straight-through connecting rods to tie together two pistons in horizontally-opposed cylinders. A a rotary drive is connected to an output shaft and to the two connecting rods to translate the linear motion produced by the pistons to rotary motion. 
   U.S. Pat. No. 6,170,443 describes a two-stroke internal combustion engine that uses a single crankshaft and two opposed cylinders having opposed inner and outer pistons reciprocally disposed to improve engine efficiency. 
   EPO. Pat. Application No. 1,039,113 describes a two-cycle internal combustion engine that uses a reciprocally movable scavenging pump to purify exhaust gas and enhance the output power and the specific fuel consumption. 
   U.S. Pat. No. 5,730,099 describes a two-stroke engine and method to promote reduction in engine exhaust emissions, comprising a combustion chamber, a fuel injector, an ignition system, an exhaust system, and a pump to periodically pump air unmixed with fuel into the combustion chamber. 
   U.S. Pat. No. 5,732,548 describes a method for reducing harmful emissions from two stroke engines while maintaining catalytic efficiency, comprising the steps of adding a platinum group metal compound to the cylinder of a two-stroke engine having a catalytic oxidizer; igniting fuel in a cylinder in the presence of the platinum group metal compound; and passing the exhaust gas containing the platinum group metal through an exhaust duct and the catalytic oxidizer. 
   U.S. Pat. Nos. 5,762,040 and 5,791,304 describe two-cycle internal combustion engines having low-pressure, cylinder wall fuel injection systems that reduce the potential of short circuiting unburned fuel through the engine exhaust port by optimizing the direction of fuel injection into the piston cavity. 
   An unfilled need exists for an apparatus and method to enhance the overall performance of engines (e.g., diesel or gasoline-fueled internal combustion engines) in one or more of the following ways: by reducing engine wear; by increasing the power output; or by reducing the level of unwanted atmospheric emissions. 
   I have discovered an apparatus and method to enhance the overall performance of engines by increasing the power output, reducing the amount of unwanted atmospheric emissions, or both. Compared to prior devices and methods that enhance the performance of engines, the novel apparatus and method also reduces engine wear. The apparatus is an engine (e.g., diesel or gasoline-fueled internal combustion engine) comprising a crankshaft, crankcase, oil pan, combustion chamber, piston, connecting rod, intake port, exhaust port, and scavenging pump assembly having an air cylinder and an air diaphragm. The connecting rod converts the reciprocal motion of the piston to rotational motion of the crankshaft. The scavenging pump assembly allows for the control of air and fuel intake port pressure by controllably boosting an intake mixture of air and fuel to a level sufficiently greater than ambient pressures, and loading the air-fuel mixture into the combustion chamber, while minimizing the potential for engine lubricating-oil to combine with the intake air-fuel mixture. Typically, the air-fuel mixture is loaded into the air cylinder using a carburetor system. However, air and fuel may be separately supplied to the combustion chamber using a fuel injector system. In this instance, air is supplied to the combustion chamber via the scavenging pump assembly, while fuel is supplied to the combustion chamber via the fuel injector system. 
   In a preferred embodiment, the scavenging pump assembly additionally allows for the reduction of engine wear as compared to that inherently caused by prior scavenging pumps actuated by the rotational movement of the crankshaft. This is achieved by relying on the reciprocal movement of the piston to colinearly actuate the air diaphragm. In this embodiment, the piston and air diaphragm are colinearly aligned and rigidly connected, using an air diaphragm connecting member that passes through the crankcase, such that as the piston compresses a loaded air-fuel mixture in the combustion chamber, it causes the air diaphragm to simultaneously draw an air-fuel mixture into the air cylinder without interfering with or relying on the rotation of the crankshaft. When the loaded mixture ignites, the piston reciprocally retracts from the combustion chamber, causing the air diaphragm to supply the new mixture to the combustion chamber through a routing assembly that routes the new mixture from the air cylinder directly to the combustion chamber, without exposing the new mixture to engine lubricating-oil contained in the crankcase and oil pan. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a cross-sectional, schematic diagram of some of the parts of one embodiment of the internal combustion engine. 
       FIG. 2  illustrates a schematic diagram of a side plan view of one embodiment of the air diaphragm driving assembly. 
       FIG. 3A  illustrates a cross-sectional, schematic diagram of some of the parts of one embodiment of the scavenging pump during the compression stroke. 
       FIG. 3B  illustrates a cross-sectional, schematic diagram of some of the parts of one embodiment of the scavenging pump during the power stroke. 
       FIG. 3C  illustrates a cross-sectional, schematic diagram of some of the parts of one embodiment of the scavenging pump during the intake stroke. 
       FIG. 3D  illustrates a cross-sectional, schematic diagram of some of the parts of one embodiment of the scavenging pump during the exhaust stroke. 
   

   The general purpose of this invention is to provide a reliable, inexpensive apparatus and method that enhances the overall performance of engines (e.g., 2-stroke and 4-stroke, diesel and gasoline-fueled internal combustion engines). The invention may be used to improve the performance of engines empowering various devices, including outboards, personal water craft, tillers, chainsaws, air blowers, weed-eaters, motorcycles, all-terrain vehicles, automobiles, trucks, etc. In a preferred embodiment, the basic design of the apparatus is that of a conventional, 2-stroke internal combustion engine (diesel or gasoline-fueled), having a crankshaft, crankcase, oil pan, combustion chamber, piston, intake port, exhaust port, and connecting rod. The mechanical components should be capable of withstanding the heat produced internally during the operation of the engine, and should have a relatively high mechanical strength, and a relatively high resistance to corrosion, friction, and wear, such as aluminum, cast iron, steel, titanium, polytetrafluoroethylene, and graphite composites. To enhance the overall engine performance, the basic design further comprises a scavenging pump assembly capable of controllably supplying the combustion chamber with an air-fuel mixture relatively free of lubricating-oil from the crankcase, and pressurizing the air-fuel mixture to a level sufficiently greater than ambient pressures without interfering with or directly relying on the rotation of the crankshaft. 
   There are several advantages to using the novel scavenging pump assembly to supply the combustion chamber with an air-fuel mixture. First, the number of components may be minimal. Fabrication may be simple and inexpensive. Second, the potential for mechanical failure of the crankshaft is reduced. The air diaphragm is colinearly aligned and rigidly fixed to the piston, and thus is actuated by movement of the piston rather than the crankshaft. Third, the design of the novel scavenging pump assembly allows for the increased power output of an engine without having to increase the overall size of the engine or any of its major components (e.g., the crankshaft, crankcase, combustion chamber, piston, or connecting rod). Fourth, the design of the novel scavenging pump assembly allows for the increased ability to maintain a sufficient level of lubricating-oil in the crankcase to lubricate meshing engine components. Fuel and air may be mixed in an air cylinder separate from the crankcase, and then routed to the combustion chamber, minimizing exposure to engine lubricating-oil contained in the crankcase. Finally, the potential for raw fuel to escape the combustion chamber during the exhaust stroke may be nearly eliminated. Air-fuel mixture loading can be delayed to provide sufficient time for the exhaust port to close. 
     FIG. 1  illustrates one embodiment of an internal combustion engine  2  in accordance with the present invention. This embodiment comprises a crankshaft  4 , a crankcase  6 , an oil pan  8  a combustion chamber  10  having a distal end  12  and a proximal end  14 , a piston  16  disposed in combustion chamber  10 , a connecting rod  18 , intake port  20 , exhaust port  22 , and a scavenging pump assembly. The scavenging pump assembly comprises an air cylinder  24  having a distal end  26  and a proximal end  28 , and an air diaphragm  30  disposed in air cylinder  24 , and a routing assembly (described below). To minimize mechanical wear caused by friction, the scavenging pump assembly additionally comprises an air diaphragm connecting member for colinearly and rigidly connecting piston  16  to air diaphragm  30 . (In this embodiment, crankcase  6  and oil pan  8  maintained a sufficient amount of lubricating-oil in engine  2  to keep all of the major components of engine  2  lubricated, including combustion chamber  10  and air cylinder  24 .) The air diaphragm connecting member comprised two pairs of stilts  32  that passed through crankcase  6 , near counterweight balancers  34 . See FIG.  2 . The dimensions and shape of stilts  32  were such that piston  16  was capable of driving air diaphragm  30  without directly relying on or interfering with the rotation of crankshaft  4  or counterweight balancers  34 . See FIG.  2 . Modifications to counterweight balancers  34  (e.g., reduction of the total width of counterweight balancers  34 ) may be required, so that stilts  32  can pass through crankcase  6  without interfering with the rotation of crankshaft  4  or movement of counterweight balancers  34 . Any adverse effects (e.g., crankshaft  4  balance offsets) caused by such modifications may be overcome by adding weights  56  onto the inside of counter-weight balancers  34  to rebalance crankshaft  4 . See FIG.  2 . 
   As illustrated in  FIG. 1 , air cylinder  24  was located opposite combustion chamber  10  and included a one-way valve assembly capable of restricting the flow of intake air-fuel mixture entering air cylinder  24  from a carburetor (not shown), such as an intake reed  36  (10202 FF series Lawn-Boy engine-Outboard Marine Corporation, Waukegan, Ill.). The dimensions and shape of the contact surface of air cylinder  24  complemented that of air diaphragm  30  such that when air diaphragm  30  was advanced towards proximal end  28  of air cylinder  24 , it compressed the intake air-fuel mixture to a level greater than ambient pressures, and prevented engine-lubricating oil contained in crankcase  6  from contaminating the air-fuel mixture in air cylinder  24 . In a preferred embodiment, air diaphragm  30  had a seal ring  38  centrally located to allow for a relatively air tight seal between air diaphragm  30  and air cylinder  24 . Seal ring  38  helped minimize the potential for lubricating-oil escaping into air cylinder  24 . Optionally, to further minimize the potential for lubricating-oil to escape into air cylinder  24 , the surface of air diaphragm  30 , adjacent to crankcase  6 , can be made concave to allow for the gathering of lubricating-oil away from seal ring  38 . To help minimize the potential for lubricating-oil to escape into combustion chamber  10 , a seal ring  40  may added to piston  16  to form a relatively tight seal between piston  16  and combustion chamber  10 . 
   As illustrated in  FIG. 1 , to further minimize the potential for contaminating the air-fuel mixture with engine lubricating-oil, the routing assembly comprised four externally-located routing pipes  42  (only one routing pipe  42  is shown) that routed the air-fuel mixture from air cylinder  24  directly to the combustion chamber  10 , without exposing the mixture to the lubricating-oil in the crankcase  6 . Optionally, a check valve  44  (Model No. 2-9280; Echlin, Inc., Branford, Conn.) may be used to maximize the flow of air-fuel mixture supplied to combustion chamber  10 , and to prevent any negative pressure formed by air cylinder  24  during the compression stroke from affecting the air-fuel mixture in routing pipe  46 . See FIG.  3 C. (Seal ring  40  also may help reduce the potential for negative pressure affecting the air-fuel mixture in routing pipes  42 .) Raw fuel emissions may be nearly eliminated by holding the air-fuel mixture in routing pipe  42  and releasing it when exhaust port  22  is closed. This may be accomplished using a solenoid valve (not shown) located in routing pipe  42  near intake port  20 , and capable of periodically allowing the air-fuel mixture in routing pipe  42  to enter combustion chamber  10  after piston  16  has reached proximal end  14  and exhaust port  22  has closed. In an alternative embodiment, a system comprising at least one intake valve (i.e., a valve located at intake port  20  and capable of inhibiting the flow of air-fuel mixture into combustion chamber  10 ; not shown), at least one exhaust valve (i.e., a valve located at exhaust port  20  and capable of inhibiting the flow of exhaust out of combustion chamber  10 ; not shown), and a camshaft (not shown) with lobes capable of periodically opening and closing the intake valve and exhaust valve, if present, as piston  16  is actuated may be used to minimize raw fuel emissions. 
   As illustrated in  FIG. 1 , routing pipe  42  extended from a point near proximal end  28  of air cylinder  24 , between check valve  44  and air diaphragm  30  (when air diaphragm  30  is farthest from distal end  26  of air cylinder  24 ), to intake port  20  located near proximal end  14  of combustion chamber  10 , between distal end  12  of combustion chamber  10  and piston  16  (when piston  16  is farthest from distal end  12  of combustion chamber  10 ). In an alternative embodiment, engine lubricating-oil contamination may be nearly avoided by routing the compressed mixture from air diaphragm  30  into combustion chamber  10  through hollow stilts  32  that form an isolated passageway from air cylinder  24  to combustion chamber  10  via crankcase  6 . To allow for a sufficient amount of lubricating-oil to remain in combustion chamber  10  and air cylinder  24  to reduce mechanical wear caused by friction, crankcase  6  should be exposed to the atmosphere using a vent  48  or vacuum (not shown). 
     FIGS. 3A-3D  illustrate schematic diagrams of one embodiment of the engine as air diaphragm  30  is actuated by piston  16 . As shown in  FIGS. 3A and 3B , as piston  16  advanced towards distal end  12  of combustion chamber  10  to compress and ignite a loaded air-fuel mixture  50 , it simultaneously pulled air diaphragm  30  towards distal end  26  of air cylinder  24 , drawing an intake air-fuel mixture  52  into air cylinder  24 . Optionally, fuel may be separately supplied to combustion chamber  10  via a fuel injection system (not shown). As shown in  FIG. 3C , when air diaphragm  30  advanced towards proximal end  28  of air cylinder  24 , it compressed intake air-fuel mixture  52  to a level sufficiently greater than ambient pressures, to begin loading combustion chamber  10 . As shown in  FIG. 3D , when loaded air-fuel mixture  50  ignited, piston  16  retracted from distal end  12  of combustion chamber  10  allowing an ignited air-fuel mixture  54  to exit exhaust port  22  just before air diaphragm  30  drove intake air-fuel mixture  52  into combustion chamber  10  through intake port  20 . 
   EXAMPLE 1 
   Construction of a Prototype 
   A 4.75 horsepower 10202 FF series Lawn-Boy engine  2  (engine specifications: 2-stroke, gasoline-fueled, internal combustion; 2.375 in bore size; 1.75 in stroke size; 121 cc displacement; 19 lb engine weight; Outboard Marine Corporation, Waukegan, Ill.) having a crankshaft  4 , crankcase  6 , oil pan  8 , combustion chamber  10 , piston  16 , and connecting rod  18  was removed from a lawmnower and modified by adding a scavenging pump assembly, as schematically illustrated in FIG.  1 . Most of the major engine components were made of aluminum, except crankshaft  4 , which was made of steel. Air diaphragm  30  was 2.371 in dia. and had a standard, combustion seal ring  38  for a 2.375 in dia. engine bore centrally located to allow for a relatively tight seal between air diaphragm  30  and air cylinder  24 . A standard, combustion seal ring  40  for a 2.375 in dia. bore was also added to piston  16  to allow for a relatively tight seal between combustion chamber  10  and piston  16 . 
   Air diaphragm  30  and piston  16  were reciprocally positioned and rigidly connected together with four, 6.0 inch long, 0.25 in dia. aluminum stilts  32 . Stilts  32  were placed at the edges of both air diaphragm  30  and piston  16 . Counter-weight balancers  34  on crankshaft  4  were modified by reducing the total width from 1.70 in to 1.30 in to provide a clearance of approximately 0.035 in between counter-weight balancers  34  and adjacent stilts  32 . 
   Air cylinder  24  had a diameter slightly greater (approximately 0.004 in) than air diaphragm  30  to allow for a relatively tight seal between air diaphragm  30  and air cylinder  24 . Intake reed  36  (Outboard Marine Corporation, Waukegan, Ill.) was placed near proximal end  28  of air cylinder  24  to prevent intake air-fuel mixture  52  entering air cylinder  24  through the carburetor from escaping back into the carburetor during the power stroke. 
   Routing pipes  42  were made of 0.375 in dia. stainless steel pipe. 
   In initial tests, the prototype was mounted on a lawnmower chassis and run for several hours. The prototype produced abnormal engine vibrations. After dismantling the prototype, it was determined that as air diaphragm  30  advanced towards distal end  26  of air cylinder  24 , a negative pressure was being generated in routing pipes  42 , which interrupted the flow of intake air-fuel mixture  52  to combustion chamber  10 . In addition, it was determined that intake port  20  over extended into crankcase  6  allowing for the generation of a negative pressure in the crankcase  6 . It was also determined that modifications to counter-weight balancers  34  offset the balance of crankshaft  4 . 
   To reduce the adverse effects of negative pressure, a check valve  44  (Model No. 2-9280; Echlin, Inc., Branford, Conn.) was inserted in routing pipes  42 , and crankcase  6  was exposed to the atmosphere using a vent  48  to prevent loaded air-fuel mixture  50  from being vacuumed out routing pipe  42  and lubricating-oil from being vacuumed out of crankcase  6 . Additionally, weights  56  were placed on the inside of counter-weight balancers  34  to balance crankshaft  4  and reduce engine vibrations. See FIG.  2 . 
   Preliminary observations suggest that the air diaphragm connecting member (i.e., stilts  32 ) effectively used the movement of piston  16  to colinearly actuate air diaphragm  30  without interfering with crankshaft  4  or counterweight balancers  34 . In addition, air diaphragm  30  and air cylinder  24  isolated the intake air-fuel mixture  52  from lubricating-oil contained in crankcase  6 , and pressurized intake air-fuel mixture  52  before driving it to combustion chamber  10  via routing pipes  42 . 
   In the future, additional tests will be conducted to confirm that the air diaphragm and air cylinder isolate the intake mixture of air and fuel from lubricating oil contained in the crankcase and reduce engine wear. Future tests will also determine alternative means for balancing the crankshaft, the effects of ambient pressure on the crankcase, and volumetric efficiency in the intake port(s) and air cylinder, in addition to determining how significant the scavenging pump assembly increases engine horsepower output, reduces unwanted atmospheric emissions, or both. 
   This scavenging pump assembly may be adapted to improve the performance of almost any internal combustion engine, including diesel and gasoline-fueled engines, by adjusting the shape and dimensions of the air cylinder, air diaphragm, air diaphragm driving assembly, and routing assembly, in addition to adjusting the supply timing of air and fuel into the combustion chamber. The scavenging pump assembly may also be used for multi-cylinder engines by adding additional air cylinders, air diaphragms, air diaphragm driving assemblies and routing assemblies. 
   The complete disclosures of all references cited in this specification are hereby incorporated by reference. In the event of an otherwise irreconcilable conflict, however, the present specification shall control.