Patent Publication Number: US-2009217903-A1

Title: Rotary internal combustion engine

Description:
TECHNICAL FIELD  
     The present invention relates to an internal combustion engine, and particularly to a rotary internal combustion engine. 
     BACKGROUND ART  
     Prior two-stroke reciprocation internal combustion engines have disadvantages of large fuel consumption, low thermal efficiency and great pollution. A four-stroke internal combustion engine have intake and exhaust valve systems which are complicated and consume a large amount of power. In such a four-stroke internal combustion engine, pistons, piston rings and cylinders are always in a friction state on the side, such that the cylinders will lose their roundness and the friction is increased, with an increased power loss and an increased difficulty in sealing. Sizes and numbers of the intake and exhaust valves, as well as the numbers of the spark plugs and fuel injectors, are limited due to the area of the top potion of a combustion chamber, thus the improvement on performance of the engine is limited. At the same time, the complicated reciprocating movement of the crankshaft connecting rod mechanism and the pistons consumes a large amount of power, and the dynamic load of individual loaded members and the wearing of the bears are increased due to the inertia of the complicated movement. Additionally, the vibration of the engine is increased, greatly influencing the increasing of the rotating speed. The mechanical power loss is up to 74%-80% (see “constitution of mechanical loss”, on page 38, section 1, chapter 2 of the book titled “Technologies for Improving the Performance of an Internal Combustion Engine”). A prior rotary polygonal piston engine can not achieve the effect of the reciprocation engine due to the difficulty of machining, problems of seal flakes (corresponding to piston rings of a reciprocation engine) and lubricating thereof and problems of fuel consumption and exhaust emission (see “rotary polygonal piston engine”, 3.3.2, on page 171, book titled “Principles and Constructions of Special Type Engines”). In conventional double rotation non-linear transmission piston internal combustion engine (disclosed in CN2313052Y) and alternate rotation piston engine (disclosed in CN1564906A), there is a problem in sealing between two pairs of pistons of the engines which are nested one another and between barrel type (cylindrical shape or circular truncated cone shape) cylinders of the engines, which problem cannot be solved. The double rotation non-linear transmission piston internal combustion engine has two groups of non-circular gears which have a limited power output and are unable to do work effectively. In the alternate rotation piston engine, gears are arranged in a manner which is not in accordance with principles of mechanics concerning inertia of high speed rotation and is unable to do work effectively. 
     CONTENTS OF THE INVENTION  
     The object of the present invention is to provide a new rotary internal combustion engine by modifying the cylinder-piston mechanism, valve mechanism and crankshaft connecting rod mechanism of the prior reciprocation internal combustion engine to solve the problems that it is difficult to seal between piston and cylinder and that the gears are not arranged in a rational and appropriate manner in the prior rotary internal combustion engines. 
     The rotary internal combustion engine of the present invention comprises a fuel supply system, a lubricating system, an ignition or fuel injection system, a cylinder-piston system and so on, and is characterized in comprising an annular cylinder with a circular section, which consists of two identical cylinder blocks  2  and  12  with a semi-circular section; two rotors  4  and  5  are installed within the cylinder block; four pistons  3  are fixed to both ends of the rotors  4  and  5  respectively; two rotor shafts  6  and  7  are vertically fixed on the two rotors  4  and  5  respectively; two non-circular gears  8  and  9  are installed on the two rotor shafts  6  and  7  respectively, and engage with two eccentric gears  10  and  11 , respectively, which are attached to the same power output shaft  13  in opposite directions, so as to constitute two gear pairs; and a spark plug or injector  25 , an intake port  20  and an exhaust port  21  are provided in required positions. 
     Comparing with the prior art, the present rotary internal combustion engine has the following advantages: 
     (1) The present structure has no dedicated valve system, so a certain amount of power can be saved.
         (2) The rotors do work four times every revolution, which equals to the amount of work done by a 4-cylinder four-stroke reciprocation internal combustion engine every two revolutions of the crankshaft. That is, the work done by one annular cylinder block of the present structure is equal to that of a 4-cylinder four-stroke reciprocation internal combustion engine.   (3) Having no complicated and bulky crankshaft connecting rod mechanism and valve system, the rotary internal combustion engine has a more simple structure, less components, a smaller volume, a lighter weight, a higher performance per liter and a smaller weight-power ratio; comparing with a  4 -cylinder four-stroke reciprocation engine with the same cylinder bore, the number, weight and volume of components in the characterized portion of the rotary internal combustion engine are reduced by about 30%, resulting in a much simpler process and a much lower cost in manufacture.   (4) The present rotary engine has no vibration due to the disadvantageous inertia of reciprocating movements of the crankshaft connecting rod mechanism, valve system and pistons; the inertia brought by the engine is well used; good balancing can be achieved at any rotating speed, making it possible to significantly increase the rotating speed.   (5) There is no friction at all between the piston and the cylinder of the present rotary internal combustion engine, and the friction phenomenon of the piston and piston rings with the side of the cylinder is avoided; the friction loss will not increase due to the side wear and tear, and the sealing will not be difficult due to the losing of roundness of the cylinder body caused by side friction; and the joint having one or two piston rings of the piston may be disposed inside the piston ring joint place  26  in the end of the rotor, as shown in  FIG. 2 , so as to resolve the problem of leakage at the joints of piston rings.   (6) Each piston of the present rotary internal combustion engine can carry out two strokes for doing work at the same time, namely, expansion stroke and exhaust stroke; and the intake stroke and compression stroke are carried out simultaneously by the same piston, as shown in  FIGS. 11-13 . Consequently, the friction between the piston rings and the cylinder is reduced by 50%, saving a large amount of power.   (7) More intake and exhaust ports can be provided in the intake and exhaust position of the present structure. The total area of the intake or exhaust ports can be larger than the area of the cylinder bore, such that the pumping loss is greatly reduced. The intake charging amount is increased. The exhaust gas can be discharged more quickly and more completely. The power is saved.   (8) Since there is no air valve in the intake port of the present structure, the intake port can be easily designed into a shape, which facilitates the formation of whirlpool of the mixture gas, such that the fuel oil is better atomized and the combustion of mixture gas is better facilitated.   (9) More spark plugs or fuel injectors can be provided in the present structure, such that the combustion is faster and has a better effect, and it facilitates to apply the lean-burn technology and the quick-burn technology.   (10) The intake and compression strokes are always carried out always in a special potion of the cylinder block, which is not heated by the combustion gas. Therefore, the fresh air intaken has a low temperature and a large density, facilitating to increase the compression ratio and the combustion efficiency.   (11) There is no disadvantageous phenomenon caused by carbon deposition in the combustion chamber, because no special combustion chamber is provided in the present structure.       

    
    
     
       DESCRIPTION OF FIGURES  
         FIG. 1  is a side view of the rotor; 
         FIG. 2  is a plan view of  FIG. 1 ; 
         FIG. 3  is a side view of  FIG. 4  in direction F; 
         FIG. 4  is a side view of a piston; 
         FIG. 5  is a plan view of  FIG. 4 ; 
         FIG. 6  is a plan view of an annular cylinder block; 
         FIG. 7  is a section view taken along the line E-E in  FIG. 6 ; 
         FIG. 8  is a schematic assembly plan view of non-circular gears and eccentric gears and the cylinder block; 
         FIG. 9  is section view of general assembly taken along the line M-M in  FIG. 8 ; 
         FIG. 10  is a schematic assembly view of the piston, non-circular gears and eccentric gears, with the cylinder block partly removed; 
         FIG. 11-13  are schematic views showing the pistons performing strokes in the cylinder. 
     
    
    
     MODE OF CARRYING OUT THE INVENTION  
     The mode of carrying out the invention will be described in detail with reference to the drawings. 
     An annular cylinder with a circular section consists of two identical cylinder blocks  2  and  12  (as shown in  FIG. 6 ) with semi-circular sections, as shown in  FIGS. 6 ,  7  and  9 . Two identical rotors  4  and  5  are installed within the cylinder block, as shown in  FIGS. 1 ,  2  and  9 . Grooves  28  for seal rings are provided on both sides of the rotors  4  and  5  and on a corresponding portion of the cylinder block, as shown in  FIGS. 2 ,  6 ,  7  and  9 , and seal rings (not shown) are provided in the grooves. Four identical pistons  3  are fixed to both ends of the rotors  4  and  5  respectively. The piston has a hole  24  which is mounted to an end of the rotor and has a piston pin hole  23  which is concentric with a piston pin hole  22  in the end of the rotor, as shown in  FIGS. 2 ,  3 ,  4  and  5 . The piston is fixed to the end of the rotor by the same piston pin or bolt as that of the reciprocation engine and the four pistons are mounted on the same level. One or more piston rings (not shown) that is the same as those of the reciprocation engine are mounted on the piston. A ring joint with one or two rings therein may be disposed inside a place  26  of a piston ring joint in the end of the rotor, as shown in  FIG. 2 . The upper and lower faces of the piston are both solid. The lubrication between the piston rings and the cylinder block and the two rotors can be performed by rotor shaft and rotor in a forced pressure discontinuous lubrication manner, namely, the pressure is not supplied when the piston passing the intake and exhaust ports. The piston can be formed into a sector shape, as shown in  FIG. 4 , or into other shapes. Two rotor shafts  6  and  7  are vertically fixed in shaft holes  27  of the two rotors  4  and  5  respectively. Two non-circular gears  8  and  9  are installed on the two rotor shafts  6  and  7  respectively, as shown in  FIGS. 8 ,  9  and  10 . A schematic assembling view of the non-circular gears, the eccentric gears and the piston, with the cylinder block partly removed is shown in  FIG. 10 . Further, an power output shaft  13  is provided, on which two identical eccentric gears  10  and  11  are mounted and are oriented in opposite directions, as shown in  FIGS. 8 ,  9  and  10 . The two eccentric gears  10  and  11  are balanced with the prior art. Two gear pairs are formed by the eccentric gears  10 ,  11  and the non-circular gears  8 ,  9 , which are engaged with each other respectively, as shown in  FIGS. 8 ,  10 . The circumference of the non-circular gear is twice as long as that of the eccentric gear. Two bears  14  and  15  are mounted on the power output shaft  13 . Four bears  16 ,  17 ,  18  and  19  fixed to the engine body are mounted on the rotor shafts  6  and  7  respectively, as shown in  FIG. 9 . A spark plug or fuel injector  25  is provided at a location on the cylinder block where the rotation angle difference between the two pistons is minimum, namely, at a center location when the volume between the two pistons is minimum. An intake port  20  and an exhaust port  21  are provided in the location corresponding to the spark plug  25 , as shown in  FIG. 8 . In addition, a fuel supply system, lubrication system, cooling system and ignition system are provided, which are substantially same as those of the prior reciprocation internal combustion engine. 
     The operating principle of the present structure is as follow: the volume between the pistons are varied by means of the rotation speed difference between the two rotors under the effect of rotation angle difference between the two groups of non-circular gear and eccentric gear, so as to successively carry out a series of working processes of intaking, compression, expansion and exhaust strokes. The processes are shown in  FIG. 11 , in which the combustible gas between the pistons A and B has been compressed and the ignition is started and the expansion stroke is started. At that time, the pistons B and D on the same rotor rotate clockwise and accelerate and power is outputted via the output shaft by the rotor shafts, non-circular gears and eccentric gears. The pistons A and C on the same rotor rotate and decelerate and at the same time the volume between the pistons A and D is in a compression stroke, the volume between the pistons D and C is in an intake stroke, and the volume between the pistons B and C is in an exhaust stroke. When the pistons reach the position shown in  FIG. 12 , the pistons A and C are slowest, the pistons B and D are the fastest, and the rotation speed difference between the two rotors is maximum. At this time, the pistons A and C begin to accelerate, and the pistons B and D begin to decelerate. When the pistons reach the position shown in  FIG. 13 , an expansion stroke is completed between the pistons A and B, a compression stroke is completed between the pistons A and D, an intaking stroke is completed between the pistons D and C, and an exhaust stroke is completed between the pistons B and C. Accordingly, the exhaust, intaking, compression and expansion strokes are completed once simultaneously between every two of the pistons respectively. Thus, when the piston complete every revolution, as shown in  FIG. 11 , when the piston A rotates back to the same position, four working strokes are completed, which corresponds to the cycle of two revolutions of the crank shaft in a  4 -cylinder four-stroke reciprocation internal combustion engine. 
     The better performance can be achieved with the larger rotation speed difference between the pistons within a preferable range. The rotation speed difference between the pistons is determined by the design of the eccentric gears and the non-circular gears. Also, the rotation speed difference can be increased by changing and adding the groups of the non-circular gears and the eccentric gears, for improving the performance. A plurality of groups of cylinder blocks with matching transmission shafts and gears can be combined to provide a larger power output. Two or more intake/exhaust ports can be provided in the present structure to reduce the pumping loss and increase the intake charging. Two or more spark plugs or fuel injectors can be provided to make the combustion more quickly and more completely. 
     Exemplary descriptions of the present invention have been made. It should be understood that, any variations, modifications or equivalents are within the protective scope of the present invention, without departing from the spirit and the scope defined by the accompanying claims.