Description ROTARY ENGINE

Technical Field

[1] The present invention relates to rotary engines. More particularly, the present invention relates to a rotary engine that performs all operations of intake, compression, expansion by combustion and exhaust only by a circular motion in place of a linear motion, and that produces power via generation of an expansion force by burning a compressed fuel-air gas mixture, which is formed by mixing clean air introduced into a rotary cylinder while forcing the gas mixture having completed work to be pushed out of the cylinder, and a fuel injected into the cylinder while the interior space of the cylinder is shrunk and compressed. Background Art

[2] Conventional piston engines suffer from problems as follows. The conventional engine is heavy and large due to a number of components, such as valves and a connecting rod to convert linear reciprocation into a circular movement. Furthermore, the conventional engine often suffers from difficulty in removal of vibration occurring upon conversion of the linear reciprocation into the circular movement, discordance of opening and closing of the valves with an increasing reciprocation speed of a piston, low efficiency due to heavy intake and exhaust burdens related to small intake and exhaust ports, and easy abrasion of a piston ring and a cylinder wall due to great force and friction of the piston exerted on the cylinder wall. Such problems are caused by the basic construction of the piston engine. These problems cause the engine to suffer from great loss of energy which is not converted to power.

[3] On the other hand, a rotary engine has the construction of directly converting an expansion force of gas into the circular movement and thus does not experience anywhere near the problems of the conventional piston engine. Since the rotary engine neither performs the linear reciprocation nor has the valves, it has merits such as a small number of components, low noise, small size and light weight. Such merits of the rotary engine have promoted development of various rotary engines. However, since only the rotary engine invented by German engineer Wankel among various rotary engines has been put into practical use, the rotary engine generally refers to a "Wankel rotary engine."

[4] In the Wankel rotary engine, a roughly triangular rotor both rotates once about its axis and makes three orbital revolutions about a spinning shaft during three rotations of the spinning shaft, for which three corners of the rotor meanderingly rotate along an inner wall of an oval-like epitrochoid- shaped housing to change the sizes of three

spaces inside the housing, performing operations of intake, compression, expansion by combustion, and exhaust.

[5] The Wankel rotary engine has merits as follows. Since all the gravity centers of the components make the circular movement, it is possible to easily remove vibration only with a balancing weight, which lowers the mechanical loss. In addition, the Wankel rotary engine provides a uniform torque by a single combustion for each rotation of the spinning shaft, has a small number of components due to no need of the valves and connecting rods for converting the linear reciprocation into the circular movement, and experiences low friction-related energy loss. As a result, the Wankel rotary engine can be operated quietly at very high speed, and produces as much power as the piston engine about twice the size of the piston engine.

[6] However, the Wankel rotary engine suffers from problems as follows. Since a corner-gap sealing pad is disposed on each triangular corner of the rotor and directly contacts flame, it becomes lowered in endurance and suffers from great friction. In addition, while the corner-gap sealing pad passes through a connection hole between an igniter and a combustion chamber, there is leakage of gas due to failure of sealing the corner gap by the corner-gap sealing pad. Furthermore, every point of side sealing pads moves along their epitrochoids different from each other and scratches a lateral side of the housing with non-uniform friction. Moreover, since processes of sucking a fuel- air gas mixture and discharging the gas mixture having completed work outside the engine are simultaneously performed in a space where an intake port is connected to an exhaust port, the engine experiences an overlap phenomenon, which is severe in the case where the intake and exhaust ports are positioned around the housing. When the intake and exhaust ports are positioned on the lateral side of the housing, it is possible to prevent the overlap phenomenon, whereas the gas mixture makes whirlpool, making it difficult to perform intake of air and provide non-uniform flame when the whirlpool rotates at high speed. As a result, the Wankel rotary engine is lowered in efficiency and causes severe air pollution. Moreover, the Wankel rotary engine is difficult to manufacture due to the epitrochoid inner surface of the housing, to increase a compression ratio, and to manipulate and repair the components thereof due to different thermal expansion coefficients of the components.

[7] A rotary engine disclosed in Korean Patent No. 0109268 filed on 1993 by the inventor of the present invention does not suffer from the aforementioned problems of the Wankel rotary engine. The rotary engine of the inventor comprises two rotary devices, each of which has a rotary cylinder making a single rotation to suck and supply gas while a spinning shaft rotates twice, and discharges the gas after performing combustion and expansion of the gas to produce power while the gas sucked and compressed into the one rotary device is moved to another rotary device. However,

such a rotary engine has a problem in that two or three rotary devices are required to constitute the rotary engine. Disclosure of Invention

Technical Problem

[8] It is an object of the present invention to provide a rotary engine that can exhibit all functions as an engine only with a single rotary device of the rotary engine disclosed in Korean Patent No. 0109268 designed to solve the problems of the conventional rotary engines. Therefore, the present invention has technical problems in view of operation for introducing clean air while discharging gas having completed work to the outside of the engine, proper locations of intake and exhaust ports for that operation, and configuration for sufficient mixture of fuel and air through uniform injection of the fuel. Technical Solution

[9] In accordance with one aspect of the present invention, a rotary engine comprises: a housing having a cylindrical interior space, an intake port through which air is introduced into the housing, and an exhaust port through which a gas having completed work is exhausted to an outside of the housing; a pair of disc-shaped housing cover plates, each including a smaller disc attached to an inner center of the cover plate and having a spinning shaft-hole formed at a location deviated from a center of the smaller disc; a rotary cylinder having inner walls facing each other, and an outer surface rounded to allow idling of the rotary cylinder and having a size corresponding to that of an inner surface of the housing; a rotary piston interposed between the inner walls of the rotary cylinder to divide a space of the rotary cylinder into two spaces and reciprocate along the inner walls of the rotary cylinder, the rotary piston having a cylindrical shaft-hole formed through a center of the rotary piston; a revolving shaft rotatably fitted into the shaft-hole formed through the center of the rotary piston; and a spinning shaft fixed at a location deviated from a center of the revolving shaft and fitted into the holes of the housing cover plates facing each other.

[10] At this time, intake and exhaust ports are opened or closed in association with a circular movement of the rotary engine such that the exhaust port can be opened earlier than the intake port. Preferably, the rotary piston further includes recessed combustion chambers defined on both faces of the rotary piston facing the opposite spaces inside the cylinder, respectively. The housing may further include an igniter or a fuel injection device to inject a fuel.

[11] With such a very simple construction as described above, the rotary engine according to the present invention can remove vibration only with a balancing weight and produce a greater output than expected in view of its size because the spinning shaft produces power by generation of an expansion force in each rotation.

Brief Description of the Drawings

[12] Fig. 1 is a cross-sectional view of a rotary engine according to one embodiment of the present invention;

[13] Fig. 2 is an exploded view of the rotary engine according to the embodiment of the present invention;

[14] Figs. 3 to 5 are cross-sectional views of a rotary engine according to another embodiment of the present invention; and

[15] Fig. 6 is a flow diagram of an operation of a rotary engine according to the present invention. Best Mode for Carrying Out the Invention

[16] Exemplary embodiments of the present invention will be described hereinafter with reference to the accompanying drawings.

[17] Fig. 1 is a cross-sectional view of a rotary engine according to one embodiment of the present invention, Fig. 2 is an exploded view of the rotary engine according to the embodiment, and Figs. 3 to 5 are cross-sectional views of a rotary engine according to another embodiment of the invention.

[18] Referring to Figs. 1 to 5, the rotary engine of the invention comprises a housing 5, a rotary cylinder 4, and a rotary piston 3, into which a revolving shaft 2 having a spinning shaft 1 eccentrically secured therein is fitted into the rotary piston 3. The housing 5 has a cylindrical interior space and is formed with an intake port 6 and an exhaust port 7. A pair of housing cover plates 11 is firmly secured to opposite sides of the cylindrical housing 5 to close the housing 5 and serves to support the spinning shaft 1 and rotors thereof. Each of the housing cover plates 11 includes a disc plate and a smaller disc plate attached to an inner center of the disc plate to form a stepped portion, and has a spinning shaft hole 12 formed at a location deviated from the center on top of the stepped portion. At either side of the rotary cylinder 4, the stepped portion is fitted into a cover plate for the rotary cylinder 4 and serves as a shaft of the rotary cylinder 4.

[19] Expansion force remaining after having completed work causes some gas mixture to burst out through the exhaust port 7 which is opened prior to the intake port 6. A blower or an air pump forces clean air to be introduced into the intake port 6 opened immediately after the exhaust port. To allow the clean air to sufficiently push the gas having completed work to the outside in a short period of time, it is desirable that the rotary engine employs the air pump, which is more powerful than the blower.

[20] The rotary engine may further comprise an injection device 9 at a suitable location around the housing 5 to inject a fuel. Since a conventional diesel engine ignites by injecting a diesel fuel in a short period of time, during which the gas mixture is

compressed, time for mixing the fuel with air is insufficient. For the rotary engine of the invention, however, the fuel can be injected into the air for a long period of time from a starting point to an ending point of a compression cycle and over a wide space in the rotary cylinder 4 which rotates, so that the fuel can be uniformly mixed with the air. It can also be contemplated that the fuel- air gas mixture is introduced into the rotary cylinder using a blower or an air pump (not shown) in place of the injection device 9. An igniter 8 is further provided to the housing 5 to ignite the compressed gas mixture by creating a spark near the time of completing the compression. This construction is better shown in Fig. 3. As in the conventional diesel engine, the rotary engine of the invention may employ the injection device 9 to cause spontaneous ignition by injecting the fuel to sufficiently compressed air without using a separate igniter 8. This construction is shown in Fig. 4.

[21] The rotary cylinder 4 has a rounded outer surface corresponding to a rounded inner surface of the housing 5, and planar inner surfaces facing each other. The rotary cylinder 4 is precisely fitted into the housing 5 to cause orbital revolution. The rotary piston 3 is reciprocably disposed between the inner planes of the rotary cylinder 4 facing each other to divide the interior space of the rotary cylinder into two spaces and has a cylindrical hole formed through the center of the rotary piston 3. Preferably, recessed combustion chambers 10 are defined on two faces of the rotary piston 3 facing the interior spaces of the rotary cylinder 4, respectively. As shown in Fig.5, spaces may be defined between the rotary piston 3 and the housing 4 so as to serve as the combustion chambers 10.

[22] The revolving shaft 2 is fitted into the hole formed through the center of the rotary piston 3 and has the spinning shaft 1 secured at a location deviated from the center of the revolving shaft 2. When the spinning shaft 1 starts spinning, the revolving shaft 2 causes the spinning shaft 1 to revolve.

[23] Hereinafter, operation of the rotary engine according to the present invention is described in detail with reference to Fig. 6. Fig. 6 shows the operation of the rotary engine according to the exemplary embodiment of the invention in sequence of a- b-c-d-e-f-a.

[24] Description of the rotary cylinder 4 will be focused on only one of the two spaces of the rotary cylinder 4 divided by the rotary piston 3. An operation "a" shows a compressed state of a gas mixture in a small combustion chamber 10. The compressed gas mixture is ignited and expands to generate an expansion force with the igniter 8. The rotary piston 3 is pushed by the expansion force in sequence of b-c-d-e to rotate the spinning shaft 1, thereby generating power. Between operations "e" and "f," the exhaust port 6 is opened to allow the gas having completed work to be discharged quickly therethrough by virtue of the remaining expansion force. In operations of f-

a-b-c, since both the intake and exhaust ports 6 and 7 are opened, clean air is introduced into the intake port 6 by the blower or the air pump while forcing the gas having completed the work to be pushed to the outside through the exhaust port 6. In operations of c-d-e-f, both the intake and exhaust ports 6 and 7 are closed and the air is mixed with a fuel injected by the injection device 9 while the air is compressed. At this time, since the fuel is injected for a relatively long period of time in a wide space inside the rotary cylinder 4 during half rotation of the spinning shaft 1, it can be uniformly mixed with the air.

[25] Here, if it is considered that input of air can produce high pressure as in the air pump, it is desirable that the intake port 6 be formed to have a larger space (not shown) to allow the intake port 6 to be somewhat opened even after the exhaust port 7 is closed by the rotary cylinder 4. This can be achieved by forming the intake and exhaust ports 6 and 7 to have the same size while arranging the intake port 6 to be located slightly behind the exhaust port 7 in the rotational direction of the rotary cylinder 4 rather than arranging the intake and exhaust ports 6 and 7 in a line. That is to say, the intake and exhaust ports 6 and 7 are located in a line around the housing such that the exhaust port 7 is opened and closed earlier than the intake port 6 by rotation of the rotary cylinder 4. With this configuration, while only the intake port 6 is opened with the exhaust port 7 closed, it is possible to further increase a compression ratio by forcibly providing air into the cylinder by means of the air pump.

[26] As described above, in the rotary engine according to the invention, a single cycle of three operations, that is, an operation of intake and exhaust, an operation of compression and fuel-air mixing, and an operation of combustion and expansion, is performed in one space of the rotary cylinder 4 for two rotations of the spinning shaft 1 and one rotation of the rotary cylinder 4. On the other hand, since such a cycle is also performed in another space of the rotary cylinder 4 in an alternating manner, it can be understood that the rotary engine produces power through the three operations described above during one rotation of the spinning shaft 1 and half rotation of the rotary cylinder 4.

[27] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Industrial Applicability

[28] The rotary engine according to the present invention has advantageous effects as follows.

[29] With a simple construction of allowing intake and exhaust ports to be opened and

closed by a circular movement of a rotary cylinder, the rotary engine is light and has a reduced size due to a small number of components. In the rotary engine, the center of gravity of all components makes only the circular movement, enabling complete prevention of vibration. Furthermore, even though the rotary engine rotates faster and faster, the rotary engine does not experience interference caused by inertia of machines unlike a piston engine. Therefore, since the rotary engine according to the invention can rotate at very high speed, it produces an increased output.