WO2008013415A1

WO2008013415A1 - Mechanism for converting motions and inner combustion engine comprising thereof

Info

Publication number: WO2008013415A1
Application number: PCT/KR2007/003595
Authority: WO
Inventors: Seiji Ishibe; Chong Kun Lee
Original assignee: Seiji Ishibe; Chong Kun Lee
Priority date: 2006-07-28
Filing date: 2007-07-26
Publication date: 2008-01-31
Also published as: KR20080010950A

Abstract

The present invention relates to a mechanism for converting motions and an inner combustion engine comprising thereof, and more specifically, to a mechanism for converting straight reciprocating motions into rotating motions and an inner combustion engine comprising thereof, in which when reciprocating motions of a piston are converted into rotating motions of crankshafts, torque can be more effectively transmitted to the crankshafts at a point of time where the piston is descended from a top dead center. The mechanism for converting motions includes a connecting rod disposed on a first axis and reciprocating along the first axis; a plurality of crankshafts disposed in such a manner that the respective axis centers thereof deviate from the first axis; a plurality of rotating members coupled to the plurality of crankshafts, respectively, so as to rotate the crankshafts; and a plurality of link rods of which one ends are rotatably are coupled to the rotating members, respectively, and the other ends are rotatably coupled to the connecting rod.

Description

MECHANISM FOR CONVERTING MOTIONS AND INNER COMBUSTION ENGINE COMPRISING THEREOF

Technical Field

[1] The present invention relates to a mechanism for converting motions and an inner combustion engine comprising thereof, and more specifically, to a mechanism for converting straight reciprocating motions into rotating motions and an inner combustion engine comprising thereof, in which when reciprocating motions of a piston are converted into rotating motions of crankshafts, torque can be more effectively transmitted to the crankshafts at a point of time where the piston is descended from a top dead center. Background Art

[2] Hereinafter, among conventional mechanisms for converting motions, a structure for converting straight reciprocating motions of a piston into rotating motions of a crankshaft, which is widely known as a structure for converting straight reciprocating motions into rotating motions, will be described. Specifically, a coupling structure of piston and crankshaft will be exemplified, which is disposed in an inner combustion engine. FIG. 1 is a diagram showing a conventional inner combustion engine having a mechanism for converting straight reciprocating motions into rotating motions. As shown in FIG. 1, the conventional inner combustion engine includes a cylinder 101 having a cylindrical hollow portion formed therein, a piston 102 reciprocating inside the cylinder 101, a connecting rod 104 of which one end is coupled to the piston, a crankshaft 103 connected to a driven shaft of a power mechanism such as a vehicle or the like, and a rotating member 105 coupled to rotate the crankshaft 103, the rotating member 105 having one side hinge-coupled to the connecting rod 104. In such a conventional inner combustion engine, the connecting rod 104 is displaced by the movement of the piston 102. Further, while the rotating member 105 is rotated by the displacement of the connecting rod 104, the crankshaft 103 is rotated so as to convert the straight reciprocating motion of the piston 102 into the rotating motion of the crankshaft 103. In the conventional inner combustion engine, a predetermined chamber C is formed between the piston 102 and a cylinder head 106 inside the cylinder 101, as shown in FIG. 1. After combustion gas and air are compressed in the chamber C, a combustion reaction is generated by ignition of an ignition plug I. Then, the piston 102 is reciprocated by the pressure of gas expanded by the combustion reaction and the rotational inertia of a fly wheel (not shown) which is rotated with the crankshaft 103. At this time, for the injection of combustion gas and air into the chamber C and the discharge of exhaust gas after the combustion reaction, a combustion gas injection valve Vl and an exhaust gas discharge valve V2 are further provided in the conventional inner combustion engine shown in FIG. 1.

[3] FIG. 2 is a schematic view for explaining the power transmission mechanism of the conventional inner combustion engine. In the conventional inner combustion engine which converts the combustion energy of combustion gas having expansion pressure caused by a combustion reaction into torque, the expansion pressure F of the combustion gas momentarily rotates the connecting rod 104 connected to the piston 102 in a direction of an arrow Q with respect to a rotation center M, as shown in FIG. 2. The momentary rotation of the connecting rod 104 is transmitted as torque which rotates the rotating member 105 connected to the other end of the connecting rod 104 so as to finally drive the crankshaft. At this time, power which rotates the connecting rod is torque (torsional moment). When a force F acts on a point of application, which is spaced at a distance r from the center of a rotating body, at a tilted angle a with respect to the center of the rotating body, and when an expansion force of expansion gas applied to the piston from the inner combustion engine is transmitted as torque for rotating the crankshaft, torque caused by the piston 102 rotating the connecting rod 104 is calculated by an outer product of a distance vector r directed from the rotation center M of the connecting rod 104 to a coupling position P3 of the connecting rod 104 and the piston 102 and the pressing force F of the piston which is transmitted to the point of application. Therefore, the magnitude of torque generated in the rotating body by the force F is calculated by the following equation: T=IFIIrlsinq.

[4] Therefore, in the conventional inner combustion engine shown in FIG. 1, the magnitude of torque applied to the connecting rod by the pressing force F of the piston can be expressed by IFIIrlsinq, when the rotation center of the crankshaft 103 is represented by Pl, the coupling position between the rotating member 105 and the connecting rod 104 is represented by P2, the coupling position between the connecting rod 104 and the piston 102 is represented by P3, an extended line connecting the positions P2 and P3 is represented by Al, an extended line connecting the positions Pl and P3 is represented by A2, and an angle between the extended lines Al and A2 is set to q.

[5] In the conventional inner combustion engine, the piston 102 compresses combustion gas and air within the chamber C at the maximum level, and then induces a combustion reaction of combustion gas. When the piston approaches a position where the combustion gas within the cylinder is compressed at the maximum level, the position is referred to as a top dead center. FIG. 3 is a schematic view showing the respective components of the conventional combustion engine when the piston approaches the top dead center. As shown in FIG. 3, when the piston approaches the top dead center, an application point of a pressing force of the piston 102 and the connecting rod 104 are positioned on the same straight line. In this case, an angle q is set to 180 degrees in the above-described equation. Therefore, when the pressing force applied to the piston around the top dead center is converted into torque and the converted torque is then transmitted to the crankshaft, the angle q is set to about 0 degrees, as described in the equation. Accordingly, the torque inevitably has a value of 0 or a value close to 0. That is, although the combustion reaction is induced in a state where the air and combustion gas are compressed at the maximum level for the enhancement of heat efficiency, the force transmitted to the crankshaft at the initial stage of the combustion reaction is 0 or close to 0, because of the limit of the transmission mechanism. Therefore, the torque generation efficiency of the inner combustion engine decreases. Although the motion conversion mechanism of piston and crankshaft, which is disposed in inner combustion engines to convert straight reciprocating motions into rotating motions, has been described so far, other motion conversion mechanisms also have such a structure that converts straight motions into rotating motions by using the piston, the crankshaft, the connecting rod, and the rotating member, as described above. Further, the construction and problem thereof are similar. Disclosure of Invention Technical Problem

[6] To solve such a problem that torque generation efficiency decreases around a top dead center where a reciprocating crankshaft approaches the highest point, the present invention provides a mechanism for converting motions and an inner combustion engine comprising thereof, in which torque has a value of more than 0 immediately after a force for descending the crankshaft is applied to the crankshaft at the top dead center. Then, when the crankshaft approaches the top dead center, torque obtained by applying a momentary force to the crankshaft has a larger value than in the conventional mechanism for converting straight reciprocating motions into rotating motions. Technical Solution

[7] According to an aspect of the invention, a mechanism for converting motions comprises a connecting rod disposed on a first axis and reciprocating along the first axis; a plurality of crankshafts disposed in such a manner that the respective axis centers thereof deviate from the first axis; a plurality of rotating members coupled to the plurality of crankshafts, respectively, so as to rotate the crankshafts; and a plurality of link rods of which one ends are rotatably coupled to the rotating members, respectively, and the other ends are rotatably coupled to the connecting rod.

[8] The connecting rod is connected to a motion generating portion which reciprocates the connecting rod. In a case of an inner combustion engine, a piston connected to a connecting rod serves as the motion generating portion. In other mechanisms for converting motions, another component serves to generate a force for vertically reciprocating a connecting rod. In an inner combustion engine according to this aspect, the piston serves as the motion generating portion and the connecting rod is reciprocated by the reciprocating motion of the piston coupled to the connected rod. Further, since the axis centers of the crankshafts are disposed to deviate from the first axis, a pressing force vector of the piston acting on the connecting rod is tilted at a predetermined angle with respect to the axis centers of the crankshafts at a top dead center where the piston approaches the highest position on the first axis. Therefore, when the pressing force of the piston is converted into torque for rotating the crankshafts, the magnitude of the torque is larger than that of the conventional mechanism for converting reciprocating motions into rotating motions. Accordingly, energy conversion efficiency increases, compared with the conventional mechanism.

[9] Preferably, the plurality of rotating members are two rotating members which are disposed symmetrically with each other with respect to the first axis, and the plurality of link rods are two link rods which are disposed symmetrically with each other with respect to the first axis.

[10] In such a structure, the plurality of link rods coupled to the rotating members are symmetrically disposed with respect to the connecting rod. Therefore, although a reaction force having a vertical directional component with respect to the motion direction of the motion generating portion such as the connecting rod and/or the piston is generated at a coupling position of one link rod and the connecting rod, a reverse reaction force is generated at a coupling position of the other link rod and the connecting rod such that the connecting rod can sufficiently support the reciprocating motions of the piston.

[11] Preferably, the rotating members are formed in a disk shape. However, the rotating members may be constructed in a shape where one ends thereof are shaft-coupled to the crankshaft, like the conventional inner combustion engine shown in FIG. 1.

[12] Preferably, the rotating members have gear portions formed on the outer peripheries thereof, respectively, so as to be geared with each other.

[13] In this structure, the rotating members are relatively moved by the gear coupling.

Therefore, the link rods coupled to the respective rotating members can be restricted in such a manner that the motions of the link rods are symmetrically performed. Therefore, it is possible to maximize such an effect that the connecting rod supports the reciprocating motions of the piston.

[14] According to another aspect of the invention, an inner combustion engine having a mechanism for converting motions comprises a cylinder having a cylindrical hollow portion formed therein, with a first axis being set to the center thereof; a piston reciprocating inside the cylinder along the first axis; a connecting rod disposed on the first axis and having one end coupled to the piston; a plurality of crankshafts disposed in such a manner that the respective axis centers thereof deviate from the first axis; a plurality of rotating members coupled to the plurality of crankshafts, respectively, so as to rotate the crankshafts; and a plurality of link rods of which one ends are rotatably coupled to the rotating members, respectively, and the other ends are rotatably coupled to the connecting rod.

[15] In this structure, motion conversion efficiency which can be obtained at the top dead center increases, compared with the conventional inner combustion engine. Therefore, it is possible to increase the efficiency of the inner combustion engine.

[16] Meanwhile, a driven shaft, which receives power from the crankshafts while being rotated with the rotation of the crankshafts, is constructed so as to be connected to any one of the crankshafts. Alternately, the driven shaft may be coupled to all the crankshafts such that the power from the crankshafts can be transmitted. For example, when one driven shaft is provided like a vehicle, the plurality of crankshafts have gear portions formed on one ends thereof, and the driven shaft has a gear portion formed on one end thereof, the gear portion corresponding to the gear portions of the crankshafts. In this case, power is transmitted from the crankshafts. However, the driven shaft does not need to receive power from all the plurality of crankshafts. When the plurality of crankshafts are geared with each other so as to be driven, the driven shaft may be connected to any one of the crankshafts. In this case, the one crankshaft connected to the driven shaft may serve as a driving shaft, and the other crankshaft may restrict a relative position between the link rods such that a power transmission loss can be prevented.

Advantageous Effects

[17] According to the present invention, when the straight reciprocating motions of the motion generating portion such as the piston is converted into rotating motions, the problem of the convention mechanism can be solved, where the connecting rod and the axis center of the crankshaft are disposed on the same axis at the top dead center of the connecting rod and/or the motion generating portion such that the torque convention efficiency decreases. Therefore, it is possible to increase the conversion efficiency of the mechanism for converting motions according to the present invention.

[18] Further, when the piston approaches the top dead center such that a combustion reaction occurs, an angle between torque, obtained by converting a pressing force generated in the piston by the expansion force of combustion gas, and vectors directed to the application point of the pressing force from the rotation center increases. Therefore, the torque has a larger magnitude than in the conventional mechanism. Accordingly, when the expansion force of compression gas is converted into the torque of the crankshafts, it is possible to obtain larger torque than in the conventional mechanism, thereby increasing the power conversion efficiency of the inner combustion engine.

[19] Furthermore, although the rotation centers of the crankshafts are disposed so as to deviate from the extended line of the movement center of the connecting rod, it is possible to prevent the deviation of the connecting rod caused by a mechanical reaction force which can be generated at this time, thereby maintaining the force transmission path of the connecting rod. Brief Description of the Drawings

[20] FIG. 1 is a diagram showing a conventional inner combustion engine.

[21] FIG. 2 is a schematic view for explaining a power transmission mechanism of the conventional inner combustion engine.

[22] FIG. 3 is a schematic view of the conventional combustion engine when a piston approaches a top dead center.

[23] FIG. 4 is a cross-sectional view of an inner combustion engine having a mechanism for converting motions according to the present invention.

[24] FIG. 5 is a schematic view for explaining a mechanical reaction force applied to the mechanism for converting motions according to the invention. Best Mode for Carrying Out the Invention

[25] Hereinafter, a mechanism for converting motions according to the present invention will be described in detail with reference to the accompanying drawings. In the following descriptions, a mechanism for converting straight reciprocating motions into rotating motions, which is disposed in an inner combustion engine, will be exemplified. However, the mechanism for converting straight reciprocating motions into rotating motions according to the invention may be applied to other apparatuses except for the inner combustion engine. In this case, the structure and effect of the mechanism are similar to those of the mechanism which is disposed in an inner combustion engine. Therefore, the detailed descriptions thereof will be omitted.

[26] FIG. 4 is a cross-sectional view of an inner combustion engine having a plurality of crankshafts according to the invention.

[27] As shown in FIG. 4, the inner combustion engine according to the invention includes a cylinder 10, a piston 20, a connecting rod 30, a plurality of crankshafts 50A and 50B, a plurality of rotating members 6OA and 6OB, and a plurality of link rods 4OA and 4OB. The cylinder 10 includes a cylinder block 105 having a hollow portion formed therein, the hollow portion having a circular cross-section about an axis Xl. The piston 20 reciprocates from a top dead center S 1 to a bottom dead center S2 inside the cylinder 10. The connecting rod 30 is coupled to one side of the piston 20 so as to extend downward along the axis Xl. The plurality of crankshafts 50A and 50B are disposed so as to be spaced from the axis Xl. The plurality of rotating members 6OA and 6OB are shaft-coupled to the crankshafts 50A and 50B so as to rotate the crankshafts 50A and 50B. One ends of the plurality of link rods 4OA and 4OB are rotatably coupled to the rotating members 6OA and 6OB, respectively, and the other ends thereof are rotatably coupled to an end of the connecting rod 30. Preferably, a cylinder head 101 of the cylinder 10 has an intake port 103 A for supplying combustion gas and an exhaust port 103B for discharging exhaust gas. Further, the piston 20 has grooves 201 and 203, which are formed on the outer periphery thereof and into which an oil ring and a sealing ring are respectively inserted.

[28] FIG. 5 is a schematic view showing the inner structure of the inner combustion engine according to the invention. Referring to FIG. 5 and the above description about the power transfer mechanism of the inner combustion engine, an expansion force of combustion gas applied to the piston 20 is converted into a torque which presses a connecting position P2 of the connecting rod 30 with the piston 20 so as to momentarily rotate the connecting rod 30. The torque is transmitted to the crankshafts through the rotating members 6OA and 6OB. In the present invention, since the axis centers of the crankshafts 50A and 50B are spaced from the axis Xl of the cylinder, a distance/direction vector r directed from the gravity center of the connecting rod 30 to an extended point of the piston 20 and a pressing force vector F of the piston 20, which is applied to the connecting rod 30, form an acute angle of more than 0 degrees, even though the piston 20 approaches the top dead center. Therefore, torque transmitted to the crankshafts through the connecting rod 30 and the rotating members 6OA and 6OB is larger than 0 at the top dead center, where a combustion reaction starts so that the expansion pressure of combustion gas is applied to the piston 20, and around the top dead center, which means the torque is larger than in the conventional mechanism. Therefore, power which can be secured at an initial stroke of the combustion reaction, in which a large amount of energy is generated, increases. Further, the mechanism can quickly reach a point of time where power is most effectively transmitted to the crankshafts, that is, a point of time where the link rods 4OA and 4OB form an angle of 90 degrees with the rotating members 6OA and 6OB, respectively, compared with the conventional mechanism. Accordingly, it is possible to increase energy conversion efficiency of the inner combustion engine and to obtain a larger amount of power than in the conventional inner combustion engine.

[29] Although not shown in FIG. 4, other components mounted on a typical inner combustion engine, for example, a fly wheel, a driving shaft connecting member of a locomotion mechanism, an adjusting unit for intake/exhaust valves and so on can be constructed and mounted in a similar manner to those of a typical inner combustion engine.

[30] As shown in FIG. 4, the plurality of crankshafts 50A and 50B (specifically, two crankshafts) are disposed symmetrically with each other with respect to the axis Xl. The link rods 4OA and 4OB for connecting the connecting rod 30 to the rotating members 6OA and 6OB are also disposed symmetrically with each other with respect to the axis Xl. Preferably, the rotating members 6OA and 6OB are constructed in a disk shape where gear portions 60 IA and 60 IB are formed along the outer periphery thereof such that the rotating members 6OA and 6OB are geared with each other.

[31] FIG. 5 is a schematic view showing a reaction force of the connecting rod which is applied to any one of the link rods. The piston 20 should be vertically reciprocated by an expansion force of combustion gas applied to the piston 20 and a force which returns the piston 20 through a fly wheel. However, a connecting member of the connecting rod 30 and the link rod 4OA is rotatably connected, and a mechanical reaction force Fr acts between the respective components of the inner combustion engine. Therefore, when a force for restricting the connecting rod 30 so as to extend along the axis Xl is not provided, the connecting rod 30' is not displaced in a direction where the piston is lifted, but is displaced by the reaction force Fr in a direction which deviates from the axis Xl, as indicated by a dashed line of FIG. 5. In the present invention, since the axis centers of the crankshafts are spaced from the axis Xl, such a problem can occur. To solve such a problem, a connecting rod guide unit for restricting the reciprocating translation motion of the connecting rod, for example, a connecting rod supporting member having a through-hole, which is formed on the axis Xl and through which the connecting rod can pass, can be additionally disposed inside the cylinder. Alternately, as shown in FIG. 4, two of the crankshafts 50A and 50B are provided, and two of the link rods 4OA and 4OB for connecting the rotating members 6OA and 6OB to the connecting rod 30 are provided. Further, the crankshafts and the rotating members are respectively disposed symmetrically with each other with respect to the axis Xl. In this structure, the reaction forces Fr act on the respective link rods, which are disposed symmetrically with each other, in opposite directions. Accordingly, the reaction forces Fr are offset, thereby preventing the connecting rod 30 from deviating from the axis Xl.

[32] In particular, when the rotating members 6OA and 6OB having the gear portions

60 IA and 60 IB formed on the peripheries thereof are rotated in a state where they are geared to each other, the link rods 4OA and 4OB can be forced to symmetrically move. Therefore, it is possible to more effectively prevent the deviation of the connecting rod 30 caused by the reaction force. [33] As such, the inner combustion engine having the mechanism for converting straight reciprocating motions into rotating motions according to the invention has been described with reference to FIGS. 4 to 5. As described above, however, in the scope of the mechanism for converting motions, a motion generating part for reciprocating the connecting rod is not limited to the piston. Further, the mechanism for converting motions can be not only applied to the structure for converting straight reciprocating motions of the connecting rod into rotating motions of the crankshafts, but also applied to a structure for converting rotating motions of crankshafts into straight reciprocating motions of a connecting rod, for example, a compressor and so on. There is no difference between the motion conversion mechanisms thereof.

[34] While the present invention has been described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications in form and detail may be made therein without departing from the scope of the present invention as defined by the following claims. Industrial Applicability

[35] According to the present invention, the mechanism for converting motions can applied to motion conversion mechanisms for converting straight reciprocating motions and rotating motions. In particular, the mechanism for converting motions can be applied to an inner combustion engine.

Claims

[1] A mechanism for converting motions comprising: a connecting rod disposed on a first axis and reciprocating along the first axis; a plurality of crankshafts disposed in such a manner that the respective axis centers thereof deviate from the first axis; a plurality of rotating members coupled to the plurality of crankshafts, respectively, so as to rotate the crankshafts; and a plurality of link rods of which one ends are rotatably coupled to the rotating members, respectively, and the other ends are rotatably coupled to the connecting rod.

[2] The mechanism according to claim 1, wherein the plurality of rotating members are two rotating members which are disposed symmetrically with each other with respect to the first axis, and the plurality of link rods are two link rods which are disposed symmetrically with each other with respect to the first axis.

[3] The mechanism according to claim 2, wherein the rotating members are formed in a disk shape.

[4] The mechanism according to claim 3, wherein the rotating members have gear portions formed on the outer peripheries thereof, respectively, so as to be geared with each other.

[5] An inner combustion engine having a mechanism for converting motions, the inner combustion engine comprising: a cylinder having a cylindrical hollow portion formed therein, with a first axis being set to the center thereof; a piston reciprocating inside the cylinder along the first axis; a connecting rod disposed on the first axis and having one end coupled to the piston; a plurality of crankshafts disposed in such a manner that the respective axis centers thereof deviate from the first axis; a plurality of rotating members coupled to the plurality of crankshafts, respectively, so as to rotate the crankshafts; and a plurality of link rods of which one ends are rotatably coupled to the rotating members, respectively, and the other ends are rotatably coupled to the connecting rod.

[6] The inner combustion engine according to claim 5, wherein the plurality of rotating members are two rotating members which are disposed symmetrically with each other with respect to the first axis, and the plurality of link rods are two link rods which are disposed symmetrically with each other with respect to the first axis. [7] The inner combustion engine according to claim 6, wherein the rotating members are formed in a disk shape. [8] The inner combustion engine according to claim 7, wherein the rotating members have gear portions formed on the outer peripheries thereof, respectively, so as to be geared with each other.