Patent Publication Number: US-6334423-B1

Title: Reciprocating piston engine and its link mechanism

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a reciprocating piston engine and its link mechanism, which is adapted for various types of engines, compressors, pumps, press machines and like machines. 
     2. Description of the Related Art 
     In general, a conventional reciprocating piston engine comprises a slider-crank mechanism, which is constructed of: a piston rectilinearly reciprocating in a cylinder; a connecting rod, which has one of its opposite ends rotatably connected with the piston through a piston pin and the other rotatably connected with a crankshaft. In this construction, the piston has its rectilinear reciprocating motion transmitted to the crankshaft through the connecting rod to convert such reciprocating motion into motion of rotation. 
     In moving the piston up and down in the conventional reciprocating piston engine, the connecting rod is tilted from the direction in which the piston moves. Due to this tilt of the connecting rod, a so-called piston slapping occurs, which is a big factor in producing vibration, noise and frictional loss in the conventional reciprocating piston engine. 
     Further, in operation, reciprocating masses in the piston and the connecting rod produce unbalanced motion. Due to such unbalanced motion, vibration and noise occur in the reciprocating piston engine. In case that the engine is of a multiple-cylinder type, unbalance couples of forces in the engine also produce vibration and noise. 
     As described above, the conventional types of reciprocating piston engines, reciprocating piston compressors, reciprocating piston pumps and the conventional crank mechanisms of press machines and like machines suffer from the above-mentioned problems. 
     SUMMARY OF THE INVENTION 
     Consequently, it is an object of the present invention to provide a link mechanism adapted for reciprocating piston engines, reciprocating piston compressors, reciprocating piston pumps and press machines and like machines, which mechanism is substantially free from any of the above problems of vibration, noise and friction loss, and is excellent in mechanical efficiency, small in size and light in weight. 
     According to a first aspect of the present invention, the above object of the present invention is accomplished by providing: 
     A link mechanism for a reciprocating piston engine and the like, characterized in that: 
     motions of a pair of cylinder-type pistons moving in opposite directions relative to each other are converted into an oscillating-type rotary motion through an oscillating arm provided with a right and a left portion, which portions are equal in mass and in turning radius of their oscillating-type rotary motions; and 
     the oscillating-type rotary motion is divided into two equal parts by connecting rod means and transmitted to the link mechanism in which the two equal parts of the oscillating-type rotary motion are converted into a rotary motion of a rotary shaft incorporated in the link mechanism. In this link mechanism, the piston path in operation may be rectilinear or circularly-curved. 
     According to a second aspect of the present invention, the above object of the present invention is accomplished by providing: 
     A link mechanism for a reciprocating piston engine and the like, characterized in that: 
     motions of a pair of circularly-curved-type pistons moving in opposite directions relative to each other are converted into an oscillating-type rotary motion through an oscillating arm provided with a right and a left portion, which portions are equal in mass and in turning radius of their oscillating-type rotary motions; and 
     the oscillating-type rotary motion is divided into two equal parts by connecting rod means and transmitted to the link mechanism in which the two equal parts of the oscillating-type rotary motion are converted into a rotary motion of a rotary shaft incorporated in the link mechanism. According to a third aspect of the present invention, the above object of the present invention is accomplished by providing: 
     A link mechanism for a reciprocating piston engine and the like, characterized in that: 
     motions of a pair of vane-type pistons moving in opposite directions relative to each other are converted into an oscillating-type rotary motion through an oscillating arm provided with a right and a left portion, which portions are equal in mass and in turning radius of their oscillating-type rotary motions; and 
     the oscillating-type rotary motion is divided into two equal parts by connecting rod means and transmitted to the link mechanism in which the two equal parts of the oscillating-type rotary motion are converted into a rotary motion of a rotary shaft incorporated in the link mechanism. 
     According to a fourth aspect of the present invention, the above object of the present invention is accomplished by providing: 
     A link mechanism characterized in that: 
     an oscillating-type rotary motion of an oscillating-type rotary shaft is divided into two equal parts by connecting rod means and transmitted to the link mechanism in which the two equal parts of the oscillating-type rotary motion are converted into a rotary motion of a rotary shaft incorporated in the link mechanism. 
     In the link mechanism of the present invention described above, in case that the piston path is rectilinear, the tilt of the connecting rod means from the direction in which the piston rectilinearly reciprocates is very small, so that a lateral pressure imposed on the piston is very small. Further, in case that the piston path is circularly-curved, substantially no lateral pressure is imposed on the piston. In any case, vibration and mechanical noise are negligible in the link mechanism of the present invention. 
     Further, in the link mechanism of the present invention, torque of the oscillating-type rotary shaft is bisected by the connecting rod means and transmitted to the rotary shaft, i.e., crank shaft, so that any unbalanced motion is completely eliminated. Furthermore, in the link mechanism of the present invention, both the connnecting rod means and the crank shaft are reduced in turning radius, and, therefore improved in rigidity, which reduces vibration and noise. Since a crank pin and the crank shaft are reduced in diameter, frictional loss is also reduced. These reductions in vibration, noise and frictional loss realize the link mechanism of the present invention for converting a reciprocating motion into a rotary motion or vice versa with a high degree of efficiency. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partially broken front view of the cylinder-type piston engine according to the present invention, illustrating the longitudianl section of the piston portion of the engine; 
     FIG. 2 is a plan view of the cylinder-type piston engine according to the present invention; 
     FIG. 3 is a sectional view of the piston portion of the circularly-curved-type piston engine according to the present invention; 
     FIG. 4 is a front view of the circularly-curved-type piston engine according to the present invention; 
     FIG. 5 is a plan view of the circularly-curved-type piston engine according to the present invention; 
     FIG. 6 is a sectional view of the piston portion of the vane-type piston engine according to the present invention; 
     FIG. 7 is a front view of the vane-type piston engine according to the present invention; 
     FIG. 8 is a plan view of the vane-type piston engine according to the present invention; 
     FIG. 9 is a front view of the link mechanism according the present invention; and 
     FIG. 10 is a plan view of the link mechanism according to the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinbelow, the present invention will be described in detail with reference to the accompanying drawings. 
     Referring now to FIGS. 1 and 2, there is shown a first embodiment of the present invention, i.e., a cylinder-type piston engine, in which a pair of cylinder-type pistons  11  and  11   a  rectilinearly reciprocate in their corresponding cyliner cases  1  and  1   a,  respectively. The cylinder cases  1  and  1   a  are provided with valve mechanisms  2  and  2   a,  respectively. 
     The cylinder-type pistons  11  and  11   a  are connected with connecting rods  13  and  13   a  through piston pins  12  and  12   a,  respectively. These two cylinder-type pistons  11  and  11   a  are equal in mass and size. The same is true between the connecting rods  13  and  13   a.  As will be hereinafter more fully described, in following each of the cylinder-type pistons  11 ,  11   a  in operation, each of the connecting rods  13 ,  13   a  is slightly tilted from a direction in which each of the cylinder-type pistons  11 ,  11   a  moves. 
     The connecting rods  13  and  13   a  have their remaining end portions rotatably connected with opposite end portions of an oscillating arm  15  through oscillating arm pins  14  and  14   a,  respectively. The oscillating arm  15  has its central portion fixedly mounted on an oscillating-type rotary shaft  40 , and is supported thereby. Consequently, in operation, the oscillating-type rotary shaft  40  is driven in an oscillating manner through the oscillating arm  15  as the cylinder-type pistons  11 ,  11   a  move up and down. The oscillating arm  15  is provided with a left and a right portion with respect to the oscillating-type rotary shaft  40 , which portions are equal in mass and in turning radius in their oscillating motions. Incidentally, though there are provided a pair of the cylinder-type pistons  11 ,  11   a  in the first embodiment of the present invention shown in FIG. 1, the number of the pistons is not limited to two only. In other words, a plurality of pairs of the pistons may be installed in the engine of the present invention. Further, a plurality of the link mechanisms of the present invention may be combined in use. 
     An oscillating-type rotary arm  41  is fixedly mounted on the oscillating-type rotary shaft  40 , and has its opposite end portions rotatably connected with connecting rods  43  and  43   a  through oscillating-type rotary arm pins  42  and  42   a,  respectively. The oscillating-type rotary arm  41  is provided with opposite end arms which are equal in turning radius in their oscillating-type rotary motions. Further, the connecting rods  43 ,  43   a  are equal in mass and size. The connecting rods  43  and  43   a  has their remaining end portions rotatably connected with crank pins  44  and  44   a,  respectively. These crank pins  44  and  44   a  are eccentrically connected with disc cranks  45  and  45   a,  respectively. 
     The disc cranks  45  and  45   a  are supported by crank rotary shafts  46  and  46   a,  respectively. These crank rotary shafts  46  and  46   a  are fixedly mounted on central portions of the disc cranks  45  and  45   a,  respectively. In operation, equally divided torque is applied to each of the disc cranks  45  and  45   a,  which rotatably drive the crank rotary shafts  46  and  46   a,  respectively. Drive gears  47  and  47   a  are fixedly mounted on the corresponding end portions of the crank rotary shafts  46  and  46   a,  respectively. These drive gears  47 ,  47   a  are meshed with a driven gear  48  fixedly mounted on a rotary shaft  49 , which forms a power output shaft. Consequently, in operation, the driven gear  48  is rotatably driven by the drive gears  47 ,  47   a.    
     The link mechanism of the present invention having the above construction operates as follows: namely, when the cylinder-type pistons  11 ,  11   a  moves up and down in opposite directions relative to each other, the oscillating arm  15  is oscillated or swung on a longitudinal center axis of the oscillating-type rotary shaft  40  as if it were a seesaw. As a result, the oscillating-type rotary shaft  40  sets up an oscillating-type rotary motion. This motion is equally divided and transmitted to each of the connecting rods  43 ,  43   a  through the oscillating-type rotary arm  41 , and further transmitted to each of the disc cranks  45 ,  45   a  in which the thus equally divided motion is converted into a rotary motion. After that, the thus converted rotary motion of each of the disc cranks  45 ,  45   a  is transmitted to each of the drive gears  47 ,  47   a,  and summed up by the driven gear  48  to rotatably drive the rotary shaft  49  on which the driven gear  48  is fixedly mounted. 
     In the above operation, the amount of tilt in each of the connecting rods  13 ,  13   a  when the cylinder-type pistons  11 ,  11   a  move up and down is very small since such tilt remains in a range of the path of each of the oscillating arm pins  14 ,  14   a.  Consequently, the lateral pressure in each of the pistons  11 ,  11   a  caused by the tilt of each of the connecting rods  13 ,  13   a  is very small. Due to this, any of vibration, noise and frictional loss caused by a large lateral pressure of the piston, is remarkably reduced, which improves the link mechanism of the present invention in mechanical efficiency to a large extent. 
     As is clear from FIG. 1, since the piston engine shown here has a right and a left half portion thereof be substantially equal in reciprocating mass, there is substantially no unbalanced motion in the piston portion of the engine. Incidentally, each of the right and the left half portion of the engine shown in FIG. 1 comprises: the cylinder-type piston  11  or  11   a ; piston pin  1  or  12   a;  connecting rod  13  or  13   a ; oscillating arm pin  14  or  14   a ; and, a left or a right half portion of the oscillating arm  15 . Further, in operation of the mechanism for converting the oscillating-type rotary motion into the rotary motion, the power of the oscillating-type rotary shaft  40  is equally divided and transmitted to the crank rotary shafts  46 ,  46   a  through the connecting rods  43 ,  43   a,  so that the rotary shaft  49  is rotatably driven through the drive gears  47 ,  47   a  and the driven gear  48 . Consequently, there is no unbalanced motion in the above mechanism. Further, transmission of the power through the connecting rods  43 ,  43   a  is performed in the same plane so that any couple of forces are not produced therein. 
     Due to the above operation in the mechanism of the present invention, frictional loss caused by the lateral pressure of the piston is reduced, which improves the mechanism of the present invention in mechanical efficiency. Further, in the mechanism of the present invention, vibration and noise both caused by inertia forces are substantially eliminated. As for vibration and noise both caused by the couple of forces, they are also substantially eliminated. 
     Now, a second embodiment of the present invention will be described with reference to FIGS. 3 to  5 . This second embodiment is an engine in which each of circularly-curved-type pistons  21 ,  21   a  performs a circularly-curved-type reciprocating motion. In the drawings: the reference numerals  1 ,  1   a  denote cylinder cases; and, the reference numerals  2 ,  2   a  denote valve mechanisms. 
     Fixedly mounted on the circularly-curved-type pistons  21 ,  21   a  are the oscillating arm  22  and a counter weight  23 . The oscillating-type rotary shaft  40  is mounted on a center of oscillating motion, i.e., fixedly mounted on a central portion of the counter weight  23 , so that both the oscillating arm  22  and the counter weight  23  are rotatably supported by the oscillating-type rotary shaft  40 . When the circularly-curved-type pistons  21 ,  21   a  move in their circularly-curved directions, the oscillating-type rotary shaft  40  is driven by the oscillating arm  22  to perform its oscillating-type rotary motion. A right and a left half portion of the oscillating arm  22  with respect to a center axis of the oscillating-type rotary shaft  40  are equal in mass and shape. Incidentally, in the second embodiment of the present invention shown in FIGS. 3 to  5 , there are provided a pair of the circularly-curved-type pistons  21 ,  21   a.  However, the number of the pistons  21 ,  21   a  is not limited thereto. A plurality of pairs of the pistons may be used. Further, a plurality of the mechanisms of the present invention may be combined with each other in the present invention. 
     In construction, the oscillating-type rotary arm  41  is fixedly mounted on the oscillating-type rotary shaft  40 , and has its opposite end portions rotatably connected with the connecting rods  43  and  43   a  through the oscillating-type rotary arm pins  42  and  42   a,  respectively. The opposite arm portions of the oscillating-type rotary arm  41  are equal in turning radius in their oscillating-type rotary motions. Further, the connecting rods  43 ,  43   a  are equal in mass and shape. The connecting rods  43  and  43   a  have their remaining end portions rotatably connected with the crank pins  44  and  44   a,  respectively. These crank pins  44  and  44   a  are eccentrically mounted on the disc cranks  45  and  45   a,  respectively. 
     The disc cranks  45  and  45   a  are supported by the crank rotary shafts  46  and  46   a,  respectively. Theses crank rotary shafts  46  and  46   a  are mounted on central portions of the disc cranks  45  and  45   a,  respectively. In operation, the disc cranks  45  and  45   a  rotatably drive the crank rotary shafts  46  and  46   a  with equal torque, respectively. The crank rotary shafts  46  and  46   a  have their end portions fixedly connected with the drive gears  47  and  47   a,  respectively. These drive gears  47 ,  47   a  are meshed with the driven gear  48  fixedly mounted on the rotary shaft  49 , which forms a power output shaft, so that the driven gear  48  is rotatably driven by the drive gears  47 ,  47   a  in operation. 
     The link mechanism of the present invention having the above construction operates as follows: namely, when the circularly-curved-type pistons  21 ,  21   a  moves in opposite directions relative to each other to perform their circularly-curved-type motions, the oscillating arm  22  is oscillated or swung on a longitudinal center axis of the oscillating-type rotary shaft  40  as if it were a seesaw. As a result, the oscillating-type rotary shaft  40  sets up an oscillating-type rotary motion. This motion is equally divided and transmitted to each of the connecting rods  43 ,  43   a  through the oscillating-type rotary arm  41 , and further transmitted to each of the disc cranks  45 ,  45   a  in which the thus equally divided motion is converted into a rotary motion. After that, the thus converted rotary motion of each of the disc cranks  45 ,  45   a  is transmitted to each of the drive gears  47 ,  47   a,  and summed up in the driven gear  48  to rotatably drive the rotary shaft  49  on which the driven gear  48  is fixedly mounted. 
     In the above operation, any lateral pressure in each of the pistons  21 ,  21   a  in their circularly-curved-type motions is eliminated, and, therefore any of vibration, noise and frictional loss caused by a large lateral pressure of each of the pistons is also eliminated, which improves the link mechanism of the present invention in mechanical efficiency to a large extent. 
     Further, there is no unbalanced motion as to the right and the left circularly-curved-type pistons  21  and  21   a,  oscillating arm  22  and the counter weight  23 . Furthermore, in operation of the mechanism for converting the oscillating-type rotary motion into a rotary motion, the power of the oscillating-type rotary shaft  40  is equally divided and transmitted to the crank rotary shafts  46 ,  46   a  through the connecting rods  43 ,  43   a,  so that the rotary shaft  49  is rotatably driven through the drive gears  47 ,  47   a  and the driven gear  48 . Consequently, there is no unbalanced motion in the above mechanism. Further, transmission of the power through the connecting rods  43 ,  43   a  is performed in the same plane so that any couple of forces are not produced therein. 
     Due to the above operation in the mechanism of the present invention, frictional loss caused by the lateral pressure of the piston is eliminated, which improves the mechanism of the present invention in mechanical efficiency Further, in the mechanism of the present invention, vibration and noise both caused by inertia forces are substantially eliminated. Furthermore, in the second embodiment of the present invention shown in FIG. 3, it is possible to reduce the reciprocating mass of the circularly-curved-type pistons  21 ,  21   a  to at least a half of that of the corresponding conventional reciprocating piston, which improves the engine in power output performance to a large extent. 
     Now, a third embodiment of the present invention will be described with reference to FIGS. 6 to  8 . This third embodiment of the present invention is a double-acting engine in which each of a pair of vane-type pistons  31 ,  31   a  performs a circularly-curved-type reciprocating motion. The engine shown in FIG. 6 may be called the displacement-type turbine engine. In the drawings: the reference numerals  1 ,  1   a  denote cylinder cases; and, the reference numerals  2 ,  2   a,    2   b,    2   c  denote valve mechanisms. 
     Fixedly mounted on the vane-type pistons  31 ,  31   a  is the oscillating arm  32 . The oscillating-type rotary shaft  40  is mounted on a center of oscillating motion performed by the oscillating arm  32 , and rotatably supports the vane-type pistons  31 ,  31   a  thereon. In operation, When the vane-type pistons  31 ,  31   a  move in their circularly-curved directions, the oscillating-type rotary shaft  40  is driven by the oscillating arm  32  to perform its oscillating-type rotary motion. A right and a left half portion of the oscillating arm  32  with respect to a center axis of the oscillating-type rotary shaft  40  are equal in mass and shape. Incidentally, in the third embodiment of the present invention shown in FIGS. 6 to  8 , there are provided a pair of the vane-type pistons  31 ,  31   a.  However, the number of the pistons  31 ,  31   a  is not limited thereto. A plurality of pairs of the pistons may be used. Further, a plurality of the mechanisms of the present invention may be combined with each other in the present invention. 
     In construction, the oscillating-type rotary arm  41  is fixedly mounted on the oscillating-type rotary shaft  40 , and has its opposite end portions rotatably connected with the connecting rods  43  and  43   a  through the oscillating-type rotary arm pins  42  and  42   a,  respectively. The opposite arm portions of the oscillating-type rotary arm  41  are equal in turning radius in their oscillating-type rotary motions. Further, the connecting rods  43 ,  43   a  are equal in mass and shape. The connecting rods  43  and  43   a  have their remaining end portions rotatably connected with the crank pins  44  and  44   a,  respectively. These crank pins  44  and  44   a  are eccentrically mounted on the disc cranks  45  and  45   a,  respectively. 
     The disc cranks  45  and  45   a  are supported by the crank rotary shafts  46  and  46   a,  respectively. Theses crank rotary shafts  46  and  46   a  are mounted on central portions of the disc cranks  45  and  45   a,  respectively. In operation, the disc cranks  45  and  45   a  rotatably drive the crank rotary shafts  46  and  46   a  with equal torque, respectively. The crank rotary shafts  46  and  46   a  have their end portions fixedly connected with the drive gears  47  and  47   a,  respectively. These drive gears  47 ,  47   a  are meshed with the driven gear  48  fixedly mounted on the rotary shaft  49 , which forms a power output shaft, so that the driven gear  48  is rotatably driven by the drive gears  47 ,  47   a  in operation. 
     The link mechanism of the present invention having the above construction operates as follows: namely, when the vane-type pistons  31 ,  31   a  moves in opposite directions relative to each other to perform their circularly-curved-type motions, the oscillating arm  32  is oscillated or swung on a longitudinal center axis of the oscillating-type rotary shaft  40  as if it were a seesaw. As a result, the oscillating-type rotary shaft  40  sets up an oscillating-type rotary motion. This motion is equally divided and transmitted to each of the connecting rods  43 ,  43   a  through the oscillating-type rotary arm  41 , and further transmitted to each of the disc cranks  45 ,  45   a  in which the thus equally divided motion is converted into a rotary motion. After that, the thus converted rotary motion of each of the disc cranks  45 ,  45   a  is transmitted to each of the drive gears  47 ,  47   a,  and summed up in the driven gear  48  to rotatably drive the rotary shaft  49  on which the driven gear  48  is fixedly mounted. 
     In the above operation, any lateral pressure in each of the pistons  31 ,  31   a  in their circularly-curved-type motions is eliminated, and, therefore any of vibration, noise and frictional loss caused by a large lateral pressure of each of the pistons is also eliminated, which improves the link mechanism of the present invention in mechanical efficiency to a large extent. 
     Further, there is substantially no unbalanced motion as to the right and the left circularly-curved-type pistons  21  and  21   a,  and the oscillating arm  32 . Furthermore, in operation of the mechanism for converting the oscillating-type rotary motion into a rotary motion, the power of the oscillating-type rotary shaft  40  is equally divided and transmitted to the crank rotary shafts  46 ,  46   a  through the connecting rods  43 ,  43   a,  so that the rotary shaft  49  is rotatably driven through the drive gears  47 ,  47   a  and the driven gear  48 . Consequently, there is substantially no unbalanced motion in the above mechanism. Further, transmission of the power through the connecting rods  43 ,  43   a  is performed in the same plane so that any couple of forces are not produced therein. 
     Due to the above operation in the mechanism of the present invention, frictional loss caused by the lateral pressure of the piston is eliminated, which improves the mechanism of the present invention in mechanical efficiency. Further, in the mechanism of the present invention, vibration and noise both caused by inertia forces are substantially eliminated. Furthermore, in the third embodiment of the present invention shown in FIGS. 6 to  8 , it is possible to reduce the reciprocating masses of the vane-type pistons  31 ,  31   a  to at least a quarter of that of the corresponding conventional reciprocating piston, which improves the engine in its power output performance to a large extent. Further, when the engine of the present invention is of a double-acting type, it is possible for the engine of the present invention to reduce its volume to one thirds of that of the corresponding conventional reciprocating piston engine, which enables the mechanism of the present invention to be small in size, light in weight and low in cost. 
     Finally, a fifth embodiment of the present invention will be described with reference to FIGS. 9 and 10. This fifth embodiment of the present invention is a link mechanism for converting a reciprocating motion into a rotary motion or vice versa. 
     In the link mechanism shown in FIGS. 9 and 10, the oscillating-type rotary arm  41  is fixedly mounted on the oscillating-type rotary shaft  40 , and has its opposite end portions rotatably connected with the connecting rods  43  and  43   a  through the oscillating-type rotary arm pins  42  and  42   a,  respectively. The opposite arm portions of the oscillating-type rotary arm  41  are equal in turning radius in their oscillating-type rotary motions. Further, the connecting rods  43 ,  43   a  are equal in mass and shape. The connecting rods  43  and  43   a  have their remaining end portions rotatably connected with the crank pins  44  and  44   a,  respectively. These crank pins  44  and  44   a  are eccentrically mounted on the disc cranks  45  and  45   a,  respectively. 
     The disc cranks  45  and  45   a  are supported by the crank rotary shafts  46  and  46   a,  respectively. Theses crank rotary shafts  46  and  46   a  are mounted on central portions of the disc crank s  45  and  45   a,  respectively. In operation, the disc cranks  45  and  45   a  rotatably drive the crank rotary shafts  46  and  46   a  with equal torque, respectively. The crank rotary shafts  46  and  46   a  have their end portions fixedly connected with the drive gears  47  and  47   a,  respectively. These drive gears  47 ,  47   a  are meshed with the driven gear  48  fixedly mounted on the rotary shaft  49 , which forms a power output shaft, so that the driven gear  48  is rotatably driven by the drive gears  47 ,  47   a  in operation. 
     The link mechanism of the present invention having the above construction operates as follows: namely, when the oscillating-type rotary shaft  40  sets up an oscillating-type rotary motion. This motion is equally divided and transmitted to each of the connecting rods  43 ,  43   a  through the oscillating-type rotary arm  41 , and further transmitted to each of the disc cranks  45 ,  45   a  in which the thus equally divided motion is converted into a rotary motion. After that, the thus converted rotary motion of each of the disc cranks  45 ,  45   a  is transmitted to each of the drive gears  47 ,  47   a,  and summed up in the driven gear  48  to rotatably drive the rotary shaft  49  on which the driven gear  48  is fixedly mounted. 
     In the above operation, the power of the oscillating-type rotary shaft  40  is equally divided and transmitted to the crank rotary shafts  46 ,  46   a  through the connecting rods  43 ,  43   a,  so that the rotary shaft  49  is rotatably driven through the drive gears  47 ,  47   a  and the driven gear  48 . Consequently, there is no unbalanced motion in the above mechanism. Further, transmission of the power through the connecting rods  43 ,  43   a  is performed in the same plane so that any couple of forces are not produced therein. 
     Due to the above operation in the mechanism of the present invention, vibration and noise both caused by inertia forces are substantially eliminated. The same is true as to vibration and noise both caused by the couple of forces. Further, since each of the connecting rods and the crank shaft may reduce its turning radius in the link mechanism of the present invention, it is possible to improve the link mechanism of the present invention in rigidity, and, therefore to reduce its vibration and noise in operation. Further, in the link mechanism of the present invention, each of the crank pin and the crank rotary shaft may reduce its diameter, which enables the link mechanism to reduce its frictional loss. Consequently, it is possible for the present invention to produce the link mechanism which is small in vibration and noise, and excellent in efficiency for converting a reciprocating motion into a rotary motion or vice versa. 
     As described above, in the reciprocating piston engine or link mechanism according to the present invention, there is substantially no vibration and noise caused by the so-called piston slapping and also caused by the couple of forces. Further, in the link mechanism of the present invention, there is substantially no lateral pressure of the pistons, and each of the crank pin and the crank rotary shaft is reduced in diameter while the link mechanism itself is of the double-acting type, so that the link mechanism of the present invention is remarkably reduced in frictional loss and remarkably improved in mechanical efficiency. Further, the link mechanism or reciprocating piston engine of the present invention is remarkably reduced in weight relative to the conventional reciprocating piston engine, which improves the engine of the present invention in power output performance while permitting the engine to be reduced in volume to at least one thirds of the volume of the conventional reciprocating piston engine. Consequently, it is possible for the link mechanism of the present invention to be small in size, light in weight, and low in cost. 
     The above construction of the present invention remarkably improves its engine in fuel consumption, electric power consumption, and in reduction of carbon dioxide discharge.