Patent Document

BACKGROUND 
   1. Field 
   The present invention relates to two-stroke internal combustion engines and more particularly to such engines which incorporate a separate compressor. 
   2. Prior Art 
   In the vast majority of prior art two stroke engines, a mixture of air, fuel and oil is injected into the crankcase where the mixture is compressed before it is fed to the cylinder head.  FIGS. 1 through 3  are diagrams of a conventional two-stroke engine, showing various positions of the cylinder during the two-stroke cycle. The upper portion of the cylinder is referred to the cylinder head area while the lower portion is referred to as the crank case area. These Figures are identical except for the position of the piston within the cylinder. From these Figures, the engine can be seen to comprise a cylinder  1 , a spark plug  2 , a piston  3 , a connecting rod  4 , a flywheel  5 , a pin through the piston  6 , a crankshaft  7 , a bypass  8 , an exhaust port  9  and an air-fuel-oil input port  15 . 
   In the operation of this prior art engine, the piston moves up and down within the cylinder. The piston is attached to one end of the connecting rod by pin  6  while the opposite end of the connecting rod is rotatably attached to the crankshaft. The reciprocating motion of the piston is converted to rotational motion by way of the crankshaft. The crankshaft motion drives the flywheel  5 . The piston can be seen to be positioned at the beginning of the up-stroke in  FIG. 1 . In  FIG. 2 , the piston has progressed farther up the cylinder, but has not reached the top of its stroke. In  FIG. 3 , the piston has passed the top of its stroke and is on the down strokes. As the piston starts the up-stroke, it draws into the crankcase an air-fuel-oil mixture through the input port  15 . Above the piston in the cylinder area is an air-fuel-oil mixture which was forced into this area from the crankcase through the bypass during the previous cycle. The bypass is a passageway which connects the crankcase with the cylinder head. The piston can block the upper end of the bypass depending on its position within the cylinder. The position of the piston in  FIG. 1  leaves unblocked both ends of the bypass  8 , allowing the mixture to flow from the crankcase into the cylinder head area. 
   As the piston moves farther up in the cylinder, as shown in  FIG. 2 , the mixture in the cylinder head area is compressed. At the top of the stroke, the spark plug  2  ignites the mixture, forcing the piston down into a down or power stroke, as shown in  FIG. 3 . It can also be seen in  FIG. 3  that on the down stroke, the piston blocks the upper end of the bypass  8  and at the same time, compresses the mixture in the crankcase area. As the piston proceeds lower, it comes to the position shown in  FIG. 1  where the piston unblocks the upper end of the bypass, letting the mixture, which is now under pressure from the down stroke, flow through the bypass and enter the cylinder head area. 
   It can also be seen in  FIG. 1  that the burnt mixture from the power stroke can escape through the exhaust port while the cylinder head area is being supplied with a fresh air-fuel-oil mixture from the crankcase. The fresh mixture from the bypass is under pressure and it aids in forcing the burnt mixture out through the exhaust port. 
   The advantage of a two stroke engine is it produces two power strokes within four strokes which, considered by itself, would theoretically produce double the power output of a four cycle engine having the same piston displacement; however, there are several disadvantages to the two stroke engine. One is fuel laden air is used to help purge the cylinder of fumes which invariably loses fuel through the exhaust pipe and lowers efficiency. A second disadvantage is that the lubricating oil has to be mixed with the fuel because a conventional splash lubricating system cannot be placed in the crankcase area of the cylinder. If oil, which is typically available in abundance in the crankcase area, is splashed about as is normal in a conventional lubrication system, this abundance of oil would unbalance the air-fuel-oil mixture necessary for the two stroke operation. 
   A number of inventions have been made to improve two stroke engines, and some have been directed at improving the lubrication system, but none have been directed at eliminating in one engine all of the shortcomings noted above. The following patents illustrated some of the prior art inventions in this area. 
   U.S. Pat. No. 4,206,727 illustrates a two stroke engine which has a main piston, an auxiliary piston and transfer valve arrangement with its associated drive mechanism. 
   U.S. Pat. No. 4,579,093 illustrates a two stroke spark ignition engine designed to eliminate the need for the typical reed valve and carburetor, and also eliminate the carbon build up inherent in the mixing of the lubricant with the fuel mixture. 
   U.S. Pat. No. 5,638,779 illustrates an internal combustion engine of either two stroke or four stroke construction which includes a block having at least one cylinder bore therein, having sidewalls carrying a liner of a structural fiber reinforced ceramic matric. 
   U.S. Pat. No. 6,478,642 illustrates an oil system for a two stroke outboard marine engine. The oil system includes a housing for the oil system which contains an inlet, an outlet and an oil return. 
   U.S. Pat. No. 6,513,464 illustrates a stratified two cycle engine comprising a cylinder having an upper end and a lower end, a head at the upper end and fuel and air intake ports at the lower end. 
   Although the prior art patents provide some improvements over the disadvantages of a two stroke engine, they do not eliminate them entirely. The specific shortcomings noted above are eliminated in the present invention which is described below. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
       FIG. 1  is a schematic drawing of a prior art two stroke engine with the piston beginning the up stroke. 
       FIG. 2  shows a prior art two stroke engine with the piston further along in the up stroke with the piston covering the upper end of the bypass. 
       FIG. 3  shows a prior art two stroke engine with the piston at the beginning of the down or power stroke. 
       FIG. 4  is a cross sectional/schematic view of the invention showing the cylinder of the present invention connected to a fan. 
       FIG. 5  is a plan view of the rolling valves. 
       FIG. 6  is a plan view of the rolling valves with elongated valve ports. 
       FIG. 7  is a side cross sectional view of a rolling valve using a recess in the plate and extension plates about the lines to the rolling valves to reduce unwanted leakage about the valves. 
       FIG. 8  is a right side view of a rolling plate carrying a recess and containing an extension plate in the recess. 
   

   SUMMARY 
   It is an object of the present invention to provide a two stroke engine with a fan that is used to provide compressed air to the engine and which allows oil to be supplied directly to the crankcase and separate from the fuel. The engine cylinder is purged with air which is free of oil, improving efficiency, fuel consumption and extending engine life. 
   It is an object of the present invention to provide a two stroke engine with a rolling valve plate that contains the engine&#39;s main intake and exhaust valves. 
   It is an object of the present invention to provide valves in the intake and exhaust lines of a two-stroke engine to optimize its performance. 
   The separate fan or compressor in the present inventions eliminates the need for adding oil to the fuel, making lubrication less of a problem. The intake and exhaust gases are passed through a unique rolling valve plate, allowing custom valve opening to optimize the performance of the engine. 
   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 4  is a cross sectional/schematic invention which shows the basic engine parts including a cylinder  1 , a piston  3 , a connecting rod  4 , an engine flywheel  5 , a crankshaft  7 , a system air intake port  20 , a fan, blower or compressor  21 , a rolling valve plate  19  which includes the engine&#39;s intake valve  31  and exhaust valve  30 , (shown in  FIG. 5 ) a carburetor  22  and a system exhaust port  14 . The principal component differences between the present invention and the prior art, are the addition of the fan  21  and the elimination of the bypass and the air-fuel-oil input port. 
   A principal operating difference between the present invention and the prior art is the air-fuel mixture produced in the carburetor is injected under pressure from the fan directly into the cylinder head to eliminate the need to compress this mixture in the crank case or feed it through the bypass to the cylinder head. In the present invention, the fan  21  is added and is driven by a mechanical linkage to the engine crankshaft. The linkage comprises the fan shaft  35 , the fan gear  29 , the timing gear  17 , the bevel gears  16 . Fan  21  takes in outside air, through system intake port  20  compresses it and then supplies it through a line  23 , carburetor  22 , line  24  and rolling intake valve  31  to the cylinder head. The exhaust path from the engine is also through the rolling exhaust valve  30  to the systems exhaust port  14 . The rolling valves are a unique feature of this invention and are explained in more detail in connection with the description of  FIG. 5 . 
   As can be seen in  FIG. 5 , the rolling plate  19  contains the input port  31  and the exhaust port  30 . This plate is caused to rotate by way of a power take off from the drive shaft  13 . The drive shaft is connected to the flywheel and derives its rotative power from the engine. The power take off is shown in  FIG. 4  to be a set of bevel gears  16  connecting a timing gear shaft  18  to the drive shaft. The timing gear shaft  18  is connected at its upper end to the timing gear  17 . The rotation of the drive shaft causes the timing gear shaft and the timing gear to rotate. The outer edge of the timing gear contains gear teeth which mesh with mating gear teeth of the outer edge of the rolling valve plate  19 , causing it to rotate. 
   The timing gear is connected to the drive shaft  13  by way of shaft  18  and bevel gears  16 , causing the timing gear to rotate as a function of the engine speed. That arrangement forces the timing gear and the plate  19  to be at a known position with respect to the values at each point in the engines cycle, admitting purging air and the air fuel mixture when required and removing exhaust fumes when required. The time that these valve openings and closings as required are listed in Table I below: 
   
     
       
             
             
             
             
           
         
             
                 
             
             
               PISTON POSITION 
               PURGE 
               INTAKE 
               EXHAUST 
             
             
                 
             
           
           
             
               Beginning down stroke 
               CLOSED 
               CLOSED 
               CLOSED 
             
             
               End of down stroke 
               OPEN 
               CLOSED 
               OPEN 
             
             
               Beginning of upstroke 
               CLOSED 
               OPEN 
               CLOSED 
             
             
               End of upstroke 
               CLOSED 
               CLOSED 
               CLOSED 
             
             
                 
             
           
        
       
     
   
   The general timing for opening and closing these valves is shown in Table II. These time and the duration of opening are optimized for each engine. The optimum times referred to here in and in the claims as the selected time or a precise time. 
   The plate  19  as shown in  FIG. 5  can be seen to be a circular disc which has two holes,  30  and  31 , passing through the plate. Hole  30  forms the engine&#39;s first exhaust valve, while hole  31  forms the engine&#39;s first intake valve. Although a disc is one shape other shapes for plate  19  can be used and are considered equivalent. Plate  19  rotates about its center  32  while theses holes pass between the lines carrying the intake and exhaust gases allowing these gases to pass through the holes at appropriate time to permit the engine to function properly. 
   Note in  FIG. 4  that the intake line  24  carrying an air-fuel mixture from the carburetor is placed directly over the engine&#39;s input port  25  with only the plate  19  separating the input line and the engine&#39;s input port. The hole  31  in plate  19  is placed at a radial distance from plate nineteen&#39;s center  32  so that this hole will pass between line  24  and port  25 , and thereby provide a path for the air-fuel mixture to enter the engine&#39;s intake for as long as the hole  31  remains between line  24  and port  25 . The period of time that the air-fuel mixture is admitted to the engine is determined by the size of the hole and the speed of rotation of shaft  19 . 
   The holes in plate  19  can take on different shapes to achieve different operating times for the valves. For example,  FIG. 6  shows plate  19  again, only there is a second and elongated exhaust valve hole  34  and a second and elongated intake valve hole  33 . 
   To take greater advantage of such larger holes in plate  19  as is shown in  FIG. 6 , a line, such as line  24 , and a port, such as port  25 , may also be elongated to encompass the elongated holes in plate  19  for a longer period. The holes when elongated have a width  43  and a length  44 . The width is determined by the valve opening required to pass the gas. The length and the speed of rotation determine how long the valve is open. 
   The description above concerning the holes in plate  19  and their general operation for the intake line  24  and intake port  25  is generally applicable to the operation of the systems exhaust port  14 , and the engine&#39;s exhaust port  26 , only it is the engine&#39;s exhaust gas that is passing from the engine exhaust port to the system exhaust port  14 , rather than from intake line  24  to input port  25 . That is, the exhaust gases emanating from engine exhaust port  26  pass through hole  30  in plate  19  to system exhaust port  14  when hole  30  is positioned between port  26  and system exhaust port  14 . 
   The speed of rotation of plate  19  is determined by the speed of drive shaft  13  and the ratio of the diameters of timing gear  17  and plate  19 . The ratio of the diameters can be adjusted to have the holes in plate  19  in the appropriate location to cause the engine to perform properly as discussed in connection with Table II. For example, when the piston is about to begin the up stroke, hole  31  is positioned between line  34  and input port  25  to admit the air-fuel mixture from the carburetor to the engine&#39;s cylinder. Although plate  19  is shown in  FIG. 4  to be generally held in a horizontal plane for ease of description in these specifications and in the claims, it is understood that the plate may be oriented in any plane and function equally well. Orientation other than horizontal are considered equivalent and are included within the spirit and scope of the invention. 
   It should be noted that fan  21  is alternatively referred to as a fan or compressor because any similar device, including a turbine, which can compress air may be suitable for this function. The function of the fan is primarily to compress air which is fed through line  23  to the carburetor  22 . Carburetor  22  accepts the compressed air and mixes it with fuel. The fuel is delivered to the carburetor through fuel line  27 . The air-fuel mixture is then fed through line  24  through hole  31  in rotating valve plate  19  to the engine intake port  25  where the compressed air-fuel mixture, first purges the cylinder and then fills the cylinder with the air fuel mixture to charge the cylinder with an explosive air fuel mixture for the power stroke. 
   The compressor in the present invention may serve a second function as a supercharger which increases the horse power of the engine considerably. A supercharger for a gasoline engine is principally a turbine placed before the carburetor to force a larger charge of air and fuel into the cylinder than would ordinarily occur without the supercharger. The compressor in the present invention is already in a position in the air supply line to the engine that is before the carburetor. It merely has to be adjusted to optimizer the correct air pressure and volume of air to the engine to obtain the supercharger effect. 
   The linkage used to drive the fan is only one of many possible ways to drive the fan. An obvious alternative is to have the drive shaft drive an electric generator which is used to drive an electric motor which in turns drives the fan. The electric motor can be more easily varied in speed as is necessary to obtain optimum turbo-charged performance and it&#39;s speed may be computer controlled to provide optimum outputs which cannot be obtained from a fixed ratio gear train. 
   Many other variations of the basic invention will be obvious to those skilled in the art after reviewing this disclosure and therefore such variations are considered within the spirit and scope of the invention. For example, in a second embodiment, rather then using an air-fuel mixture to purge the cylinder, the cylinder can be purged with air only by using a line  36 , shown in  FIG. 4 , which goes directly from the output of the fan to plate  19 . Plate  19  includes another hole  41  shown in  FIG. 5  which allows only air into the cylinder to purge the cylinder before the air fuel mixture is fed into the cylinder. Line  36  is over hole  41  prior to the admittance of the air fuel mixture and accepts air under pressure to the engine inlet port to purge the cylinder of exhaust gases. This will improves efficiency by preventing fuel from being ejected from the cylinder during purging. Hole  41  in plate  19  constitutes an air purging valve with an inlet and outlet port. The inlet port is formed by the lower end of line  36  which is in contact with plate  19  and the outlet of the air purging valve is formed the upper end of line  42  which goes from the plate  19  to the engine&#39;s cylinder input. 
   The operation of the engine in the first embodiment of the present invention is in many ways similar to prior art two stroke-engines with the air-fuel mixture being used partially to purge exhaust fumes from the cylinder and also to supply an explosive mixture to the cylinder in preparation for the power stroke. The differences between prior art two stroke engines and the first embodiment of the present invention are the air fuel mixture is compressed in the compressor rather than in the crankcase and it is injected into the cylinder through conduit line  24  and the rolling plate  19 , eliminating the need for a bypass. 
   One of the principal advantage of the present invention is the elimination of the need to mix oil and fuel to lubricate the engine. This system allows the supplying of oil separately to the engine crank case which is a great convenience during fueling. Another advantage is the reduction in carbon build-up due to the elimination of the burning of lubricating oil. This latter advantage extends the life of the engine. Still another advantage is the fine tuning of the engine through the shaping of the intake and exhaust ports which can be elongated, tear shaped or shaped otherwise to control the timing, rate and amount passed to or from the engine. An elongated valve port in plate  19  is shown in  FIG. 6  where elongated ports  33  and  34  are shown. This is another feature which improves efficiency and is not easily obtained by conventional valves. 
   To reduce leakage about the rolling valves, greater contact area about the lines and the rolling plate can be achieved by the arrangement shown in  FIGS. 7 and 8 .  FIG. 7  is a side cross sectional view of a rolling valve using a circular recess  38  in the plate  19  about line  24  and an extension plate  37  which rides in the recess and is attached about line  24 . The extension plates are shaped to fit within the circular recess as shown. 
     FIG. 8  is a side view of the arrangement shown in  FIG. 8 . It can be seen that the extension plate extends the coverage by the line  24  over plate  19  and also aids in preventing leakage from elongated holes that are longer than the diameter of line  24 .

Technology Category: 2