Patent Publication Number: US-2003226524-A1

Title: Bazmi&#39;s six stroke engine

Description:
BACKGROUND OF THE INVENTION  
       [0001] The invention relates to reciprocating piston internal combustion engines and in particular to six-stroke type. Some of reciprocating internal combustion engines are of two-stroke type, but most of them are of four-stroke type. There are four strokes in one cycle in a four-stroke engine, namely an intake stroke, a compression stroke, a power stroke and an exhaust stroke respectively. There are various modes of cycling the intake and exhaust gases during the operation of six-stroke engines to improve energy efficiency.  
       [0002] There should be at least two valves in each cylinder. One valve is an intake valve that opens in intake strokes and the other is an exhaust valve that opens in exhaust strokes. In order to increase engine efficiency, the area of the intake and exhaust valves and ports should be increased so that more fuel-air mixture is introduced into the cylinder in the intake stroke and more exhaust gases are expelled from the cylinder in the exhaust stroke. That is why piston internal combustion engines with three, four or five valves per cylinder are manufactured. It is to be noted that in a five valve per cylinder engine the area of each valve is less than that of a two valve per cylinder engine providing the cylinders and displacement of both engines are considered the same.  
       SUMMARY OF THE INVENTION  
       [0003] The main object of the invention is to increase the area of the intake and exhaust valves and ports in order to generate a large power and torque and also improve engine efficiency. The novelty of the invention is that all combustion chamber valves function as both intake valves and exhaust valves; in other words, in the intake stroke fuel-air mixture goes into a cylinder via the intake ports and all of the four combustion chamber valves and in the exhaust stroke exhaust gases are expelled from the cylinder via the same combustion chamber valves. The intake ports and exhaust ports are connected to each other in the cylinder head. Therefore, in this engine the area of the intake and exhaust valves and ports increases up to one hundred percent with respect to the area of the intake and exhaust valves and ports in an ordinary four valve per cylinder engine. It should be noted that the name of said combustion chamber valves is intake-exhaust valves or (inlet-outlet valves).  
       [0004] In order to provide a one-way flow of fuel-air mixture sucked into the cylinder via the intake ports and the intake-exhaust valves in the intake stroke and exhaust gases expelled from the cylinder and cylinder head via the same intake-exhaust valves and the exhaust ports in the exhaust stroke, especial exhaust valves are installed in the cylinder head out of the combustion chamber. Said exhaust valves close in the intake stroke and open in the exhaust stroke. As a result, in the exhaust stroke, exhaust gases do not go into the intake ports in the cylinder head.  
       [0005] There is a need for an interval so as to expel exhaust gases completely from the cylinder head. There is also a need for a mechanism to close the combustion chamber valves (intake-exhaust valves) at the end of the exhaust stroke and open them at the beginning of the intake stroke of the next cycle within the interval. Therefore, the fifth stroke and the sixth stroke are considered for the engine related to the invention; in other words, the engine operates on a six-stroke cycle. The six-stroke cycle consists of an intake stroke, a compression stroke, a power stroke, an exhaust stroke, the fifth stroke and the sixth stroke respectively.  
       [0006] The invention is feasible in both gasoline engines and diesel engines. The invention is also practicable in multi-cylinder engines.  
       [0007] Especial cams are designed for the valves of the engine. The radius and circumference of said cams are fifty percent larger than the radius and circumference of the traditional ones used in a four-stroke engine in order to cover all of the six strokes. In that case, there is no need to change the camshaft-to-crankshaft gear ratio used in a traditional four-stroke engine. The cams of the combustion chamber valves (intake-exhaust valves) have at least two cam lobes. These two cam lobes are considered for the intake stroke and the exhaust stroke. Third cam lobe is considered for only two cams of two intake-exhaust valves. The third cam lobe opens said two valves of the combustion chamber valves (intake-exhaust valves) in the middle of the fifth stroke and closes them in the middle of the sixth stroke in order to prevent pressure inside the cylinder from reducing while a piston moves downward at the end of the fifth stroke and moves upward at the beginning of the sixth stroke.  
       [0008] Other especial cams are also designed for the exhaust valves, which are in the cylinder head out of the combustion chamber. These cams are designed in a manner that said exhaust valves open at the beginning of the exhaust stroke and close in the middle of the sixth stroke. Said exhaust valves close in the middle of the sixth stroke so that the exhaust gases are expelled completely from the cylinder head within the fifth stroke and the first half of the sixth stroke. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0009]FIG. 1 is a vertical cross-sectional view of the cylinder and cylinder head related to the invention.  
     [0010]FIG. 2 is a horizontal cross-sectional view showing the ports and valve seats of the cylinder head.  
     [0011]FIG. 3 is a view of the cam exclusive for the combustion chamber valves (intake-exhaust valves) A, B, C and D. Said cam is shown by  24  in FIG. 1.  
     [0012]FIG. 4 is a view of the cam exclusive for the exhaust valves E and F, which are in the cylinder head out of the combustion chamber. Said cam is marked with  23  in FIG. 1.  
     [0013]FIG. 5 is a view of a traditional cam used in a four-stroke engine.  
     [0014]FIG. 6 is a front view of a crankshaft especially designed for a six-stroke four-cylinder engine related to the invention.  
     [0015]FIG. 7 is a right view of the FIG. 6.  
     [0016]FIG. 8 is a  3 D perspective view of the FIG. 7.  
     [0017]FIG. 9 is an exploded view of the FIG. 8.  
     [0018]FIG. 10 shows a rocker arm with a ratio of 1 to 1.8 marked with G to H. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0019] In the drawings, reference characters referring to combustion chamber valves (intake-exhaust valves) are A, B, C and D for clarity. In addition, reference characters used for exhaust valves, which are in a cylinder head out of the combustion chamber, are E and F.  
     [0020] Referring to FIGS. 1 and 2, in an intake stroke the four combustion chamber valves (intake-exhaust valves) A, B, C and D are open and the exhaust valves E and F are closed. As a result, in the intake stroke, fuel-air mixture is drawn into a cylinder  21  via intake ports  1 ,  2 ,  3  and  4  and the intake-exhaust valves A, B, C and D. In a compression stroke and a power stroke, all of the intake-exhaust valves A, B, C and D are closed and also the exhaust valves E and F remain closed. In an exhaust stroke, the intake-exhaust valves A, B, C and D open again. The exhaust valves E and F also open in the exhaust stroke. As a result, in the exhaust stroke, the exhaust gases are expelled from the cylinder  21  and the cylinder head  22  via the same valves A, B, C and D and exhaust ports  5 ,  6 ,  7  and  8  and the exhaust valves E and F. The exhaust ports  5  and  7  are connected to the exhaust valve E, and the exhaust ports  6  and  8  are connected to the exhaust valve F in the cylinder head  22 .  
     [0021] Closing of the exhaust valves E and F and opening of the intake-exhaust valves A, B, C and D in the intake stroke and opening of the exhaust valves E and F and also opening of the intake-exhaust valves A, B, C and D in the exhaust stroke effect a one-way flow of fuel-air mixture drawn into the cylinder head  22  and the cylinder  21  via the intake ports  1 ,  2 ,  3  and  4  in the intake stroke and exhaust gases expelled from the cylinder and cylinder head via the exhaust ports  5 ,  6 ,  7  and  8  and exhaust valves E and F in the exhaust stroke. Therefore, in the exhaust stroke exhaust gases do not go into the intake ports in the cylinder head. Of course, one-way valves like Reeds (not shown) can be utilized in the intake ports  1 ,  2 ,  3  and  4  to improve the continuity of said one-way flow.  
     [0022] There is a need for an interval so that the exhaust gases are expelled completely from the cylinder head and are not sucked into the cylinder in the intake stroke of the next cycle. There is also a need for a mechanism to close the intake-exhaust valves A, B, C and D at the end of the exhaust stroke and open them at the beginning of the intake stroke of the next cycle within the interval. Thus, the fifth stroke and the sixth stroke are considered for the engine. Therefore, the engine operates on a six-stroke cycle. On the fifth stroke, a piston  20  moves downward from a top dead center to a bottom dead center, and on the sixth stroke the piston moves upward from the bottom dead center to the top dead center.  
     [0023]FIG. 3 shows a cam exclusive for the intake-exhaust valves A, B, C and D. There are three cam lobes on the cam. The cam lobe  9  is designed to open the intake-exhaust valves A, B, C and D in the intake stroke. The cam lobe  10  is designed to open the same valves in the exhaust stroke. The cam lobe  11  is designed only for two cams of two intake-exhaust valves A and D. The cam lobe  11  is designed to open the valves A and D approximately in the middle of the fifth stroke and close them in the middle of the sixth stroke. It should be noted that the intake-exhaust valves B and C are closed during the fifth and the sixth strokes.  
     [0024]FIG. 4 shows a cam exclusive for the exhaust valves E and F. There is a cam lobe  12  on the cam. The cam lobe  12  is designed to open the exhaust valves E and F at the beginning of the exhaust stroke. The cam lobe  12  causes said valves to begin closing in the middle of the exhaust stroke and close them completely in the middle of the sixth stroke.  
     [0025] The intake-exhaust valves A, B, C and D close at the end of the exhaust stroke, but the exhaust valves E and F stay open. The fresh air going into the cylinder head via the intake ports  1 ,  2 ,  3  and  4  expels remained exhaust gases in the exhaust ports  5 ,  6 ,  7  and  8  completely from the cylinder head within the fifth stroke and the first half of the sixth stroke.  
     [0026] In order to prevent the pressure inside the cylinder  21  from reducing while the piston  20  moves downward in the second half of the fifth stroke and moves upward in the first half of the sixth stroke, the two intake-exhaust valves A and D open in the middle of the fifth stroke and close in the middle of the sixth stroke. The fresh air is drawn into the cylinder during the second half of the fifth stroke and expelled from the cylinder during the first half of the sixth stroke along with the exhaust gases remained in the combustion chamber from the exhaust stroke of the previous cycle. It causes the exhaust gases, which are remained in the combustion chamber from the previous exhaust stroke, to be expelled from the cylinder. This improves the engine efficiency and also reduces the proportion of unbumt fractions in the exhaust gases.  
     [0027] Due to the suction caused by the previous intake stroke, even in the exhaust stroke, fresh air is introduced into the cylinder head via the intake ports  1 ,  2 ,  3  and  4  and is expelled from the cylinder head via the exhaust ports  5 ,  6 ,  7  and  8  along with the exhaust gases expelled from the cylinder. The fast movement of the fresh air and exhaust gases through the intake and exhaust ports reduces the pressure of the gases in the ports of the cylinder head in the exhaust stroke. The low pressure of the gases inside the ports expedites the exhaustion. In order to further improve the exhaustion, the cam lobe  12  of the cams exclusive for the exhaust valves E and F can be designed in a way that said valves open some degrees of crankshaft angle before the beginning of the exhaust stroke. The mixing of the fresh air and the exhaust gases in the exhaust ports  5 ,  6 ,  7  and  8  also reduces the pollution products of the exhaust. When the exhaust valves E and F close in the middle of the sixth stroke, the pressure inside the ports of the cylinder head increases before the intake stroke of the next cycle.  
     [0028]FIG. 5 shows a traditional cam used in a four-stroke engine. The distance that a valve is lifted (valve lift) is marked with 14. The distance that a valve stays up (valve duration) is marked with 13.  
     [0029] As it was aforementioned, the engine is a six-stroke engine. Therefore, a working cycle does not correspond to 720 DEG but 1080 DEG crankshaft angle. In order not to change the camshaft-to-crankshaft ratio used in a four-stroke engine, the radius and circumference of the cams of the valves A, B, C, D, E and F are designed fifty percent larger than the radius and circumference of the traditional ones. So the larger cams cover the six strokes. As a result, the valve duration of the valves A, B, C and D,  15  (FIG. 3) designed for the six stroke engine equals the valve duration of an ordinary valve  13  (FIG. 5) used in a four-stroke engine, (Arc length 15=Arc length 13). As it was aforesaid, the arc length 15 equals the arc length 13 and the circumference of the cams of the valves A, B, C and D are larger than the circumference of the ordinary ones, so the valve lift of the valves A, B, C and D,  16  (FIG. 3) should be reduced with respect to the valve lift of the ordinary one  14  (FIG. 5) so that the cams and rocker arms function together smoothly and efficiently, (length of line  14 &gt;length of line  16 ). The reduction in valve lift of the valves A, B, C and D can be compensated by rocker arms with an approximate ratio of 1 to 1.8 marked with G to H in FIG. 10. The two rocker arms of the four rocker arms allocated for the valves A, B, C and D are marked with  18  and  19  in FIG. 1.  
     [0030] Because of the pressure of the exhaust gases and the same size of the valves A, B, C and D in area, the valve lift of the valves A, B, C and D,  17  (FIG. 3) in the exhaust stroke can be less than the valve lift of the same valves in the intake stroke  16  (FIG. 3) in order to improve energy efficiency, as the area of the intake valves are larger than that of the exhaust valves in an ordinary engine.  
     [0031] In order to prevent fuel-air mixture from wasting in a gasoline engine with a carburetor when the exhaust valves E and F are open, one of the valves A, B, C or D can be assigned as an intake valve and the other three valves can be assigned as intake-exhaust valves. In that case, the intake valve only is connected to the carburetor. Therefore, four valves are open in the intake stroke, but only three valves are open in the exhaust stroke. In that case, the length of the line  14  (FIG. 5) can be equal to the length of the line  16  (FIG. 3) that means all combustion chamber valves in the intake stroke and three combustion chamber valves in the exhaust stroke are open and lifted completely and equally.  
     [0032] Although exhaust gases expelled from the cylinder  21  are expelled from the cylinder head  22  via the exhaust valves E and F in the exhaust stroke, the fifth stroke and the first half of the six stroke, the area of the exhaust valves E and F should be designed proportionately to cover the exhaust gases expelled from cylinder  21  via the intake-exhaust valves A, B, C and/or D completely and efficiently within said strokes.  
     [0033] The cam lobe  9  (FIG. 3) can be designed in a manner that the valves A, B, C and D open earlier for the intake stroke, namely at the end of the sixth stroke. By the same token, the cam lobe  10  can also be designed in a manner that the valves A, B, C and D close later for the exhaust stroke, namely at the beginning of the fifth stroke. Unlike the traditional engine, the problem of overlapping of the combustion chamber valves will not occur in this engine especially at low engine speeds.  
     [0034] Because the valves A, B, C and D open and close rapidly at higher RPMs, there is a very short time for the intake charge to go into the cylinder in the intake stroke. As it was mentioned, the valves E and F close in the middle of the sixth stroke. Of course, with a valve variable timing device, at higher RPMs, the valves E and F can be closed at the end of the sixth stroke. It causes that the fresh air does not stagnate inside the cylinder head in the intake ports  1 ,  2 ,  3  and  4  onto the backside of the valves A, B, C and D at higher RPMs. As soon as, the valves A, B, C and D are open at the beginning of the intake stroke, the fresh air goes into the cylinder rapidly. Therefore, more fresh air is rapidly available to the cylinders. This improves the suction especially at higher RPMs.  
     [0035] There are six valves per cylinder in this engine, the four combustion chamber valves (intake-exhaust valves) A, B, C and D and the two exhaust valves E and F in the cylinder head out of the combustion chamber. Four rocker arms are installed for the intake-exhaust valves. The two rocker arms  18  and  19  can be shown in FIG. 1.  
     [0036] Because a working cycle consisting of an intake stroke, a compression stroke, a power stroke, an exhaust stroke, the fifth stroke and the sixth stroke corresponds to 1080 DEG of crankshaft angle in this engine, two pistons of the two cylinders, having subsequent firing order, are 270 DEG apart on the crankshaft in a six-stroke four-cylinder engine. FIGS. 6, 7,  8  and  9  show different views of a crankshaft especially designed for the six-stroke four-cylinder engine. FIG. 6 shows symmetrical position of the journals designed for the six-stroke four-cylinder engine. In FIGS. 6, 7,  8  and  9 , journals  25 ,  26 ,  27 ,  28  (firing order  1 - 3 - 4 - 2 ) are related to the first cylinder, the third cylinder, the fourth cylinder and the second cylinder respectively in the six-stroke and four-cylinder engine (not shown). The vibration of the six-stroke four-cylinder engine utilizing said crankshaft is less than that of a four-stroke four-cylinder engine with a traditional crankshaft.  
     [0037] Two pistons of the two cylinders, having subsequent firing order, are 180 DEG apart on the crankshaft in a six-stroke six-cylinder engine related to the invention (not shown). Therefore, the form of the crankshaft used in the six-stroke six-cylinder engine is like the form of the crankshaft used in a four-stroke four-cylinder engine with two more journals. About other multi-cylinder engines, you divide the number 1080 by the number of cylinders, for example 6 or 8, in order to find the interval between power strokes.