WO2005083255A1

WO2005083255A1 - Rotary type stirling engine

Info

Publication number: WO2005083255A1
Application number: PCT/KR2005/000516
Authority: WO
Inventors: Jong-Yub Sa
Original assignee: Jong-Yub Sa
Priority date: 2004-02-26
Filing date: 2005-02-25
Publication date: 2005-09-09
Also published as: KR20050087380A

Abstract

The present invention relates to a Stirling engine, and more particularly, to a Stirling engine that has a rotary displacer and a piston reciprocating a cooperation with a rotatable shaft of the displacer. The rotary type Stirling engine of the present invention comprises a hollow cylindrical housing that has a compressible working fluid hermetically contained therein and includes a hot heating portion for heating the working fluid and a cold cooling portion for cooling the working fluid in contact with the working fluid; a rotatable shaft rotatably supported by the housing while a portion thereof is accommodated within the housing; a displacer that has one end secured on the rotatable shaft and has an insulation surface placed in close proximity to the heating or cooling portion so as to block heat transfer from the heating portion to the working fluid or from the working fluid to the cooling portion upon rotation of the displacer; a volume-changing means communicating with the housing so that the working fluid flows therebetween, and having a volume varying in response to changes in the pressure of the working fluid; and a power-transmitting means for transmitting power, which is generated through repeated expansion and contraction of the volume-changing means in response to the changes in the pressure of the working fluid upon rotation of the displacer, to the rotatable shaft.

Description

ROTARY TYPE STIRLING ENGINE

Technical Field The present invention relates to a Stirling engine, and more particularly, to a

Stirling engine that has a rotary displacer and a piston reciprocating coupled with a rotatable shaft ofthe displacer.

Background Art Fig. 8 shows air-standard Stirling cycle diagrams. Generally, a Stirling engine is an engine in which heat is transferred from the surroundings to a compressible working fluid contained in a closed space during isochoric process 2-3 and isothermal expansion process 3-4 and is discharged to the surroundings during isochoric process 4-1 and isothermal compression process 1-2, as shown in the diagrams of Fig. 8. The Stirling engine repeats these processes to convert thermal energy transferred from the surroundings into mechanical energy such as a rotating motion, or to convert mechanical energy provided from the surroundings into thermal energy. An ideal Stirling engine has an advantage in that it can perform energy conversion with efficiency proximate to that of a Carnot cycle and thus has high thermal efficiency. Fig. 9 schematically shows the structure of a conventional simple Stirling engine for converting thermal energy into mechanical energy. The conventional Stirling engine shown in Fig. 9 is a type of Sterling engine with a displacer 40 reciprocating within a closed reservoir and a power piston 80. The displacer 40 takes the form of a disk and is installed to vertically move within a cylindrical closed reservoir 30 with a compressible working fluid contained therein, and the power piston 80 is installed to vertically move within a cylinder 70 that is placed outside of and communicates with the reservoir. Further, an upper side plate 20 of the closed reservoir 30 is maintained at low temperature to cool the working fluid, and a lower side plate 10 thereof is maintained at high temperature to heat the working fluid. The displacer 40 is made of an insulation material to block heat transfer between the upper and lower side plates. When the displacer 40 is positioned at a high level, it blocks the cooling function of the upper side plate 20 so that the lower side plate 10 can heat the working fluid within the closed reservoir 30. When the displacer 40 is placed at a low level, it blocks the heating function of the lower side plate 10 so that the upper side plate 20 can cool the working fluid within the closed reservoir 30. The displacer 40 and the power piston 80 are connected to a crankshaft 60 via connecting rods 50 and 51, respectively. To ensure a smooth rotating motion of the crankshaft 60, a flywheel 90 is installed at an end of the crankshaft 60. The Stirling engine constructed as above converts thermal energy of a hot portion into mechanical energy by repeatedly performing compression cooling and expansion heating according to the reciprocating motions of the displacer 40 and the power piston 80 that are connected to the crankshaft 60 with a phase difference of 90 degrees, respectively. However, the Stirling engine with the conventional structure has problems in that the structure of the crankshaft is complicated to establish the phase difference of 90 degrees between the displacer and the power piston, and the reciprocating displacer should be accelerated or decelerated at top and bottom dead points, which result in inertial energy loss and low efficiency. Further, since the displacer is constructed to reciprocate, the displacer and the connecting rod slidably move relative to the closed reservoir in contact with walls of the closed reservoir. Thus, there is a problem in that energy loss due to friction generated by the sliding movement lowers efficiency.

Disclosure of Invention The present invention is conceived to solve the aforementioned problems. An object of the present invention is to provide a novel rotary type Stirling engine having a displacer that rotates instead of reciprocating to reduce inertial energy loss due to the reciprocating motion and energy loss due to friction of the reciprocating displacer in the conventional Stirling engine, thereby improving efficiency. Another object of the present invention is to provide a rotary type Stirling engine capable of continuously converting thermal energy into mechanical energy, wherein a cylindrical closed space in which a displacer is rotated is divided into a plurality of heating and cooling spaces, and a power piston is connected to repeat compression and expansion as many times as the numbers ofthe heating and cooling spaces. According to the present invention for achieving these objects, there is provided a rotary type Stirling engine, comprising a hollow cylindrical housing that has a compressible working fluid hermetically contained therein and includes a hot heating portion for heating the working fluid and a cold cooling portion for cooling the working fluid; a rotatable shaft rotatably supported by the housing while a portion thereof is accommodated within the housing; a displacer secured on the portion of the rotatable shaft accommodated within the housing so as to block heat transfer from the heating portion to the working fluid or from the working fluid to the cooling portion upon rotation of the displacer; a volume-changing means communicating with the housing so that the working fluid flows therebetween, and having a volume varying in response to changes in the pressure of the working fluid; and a power-transmitting means for transmitting power, which is generated through repeated expansion and contraction of the volume-changing means in response to the changes in the pressure of the working fluid upon rotation of the displacer, to the rotatable shaft. With the present invention, the displacer secured on the rotatable shaft blocks both heat transfer from the heating portion of the housing to the working fluid and heat transfer from the working fluid to the cooling portion in response to rotation of the rotatable shaft. When the displacer made of an insulation material approaches the cooling portion and blocks the heat transfer from the working fluid to the cooling portion, the heating portion heats the working fluid to cause the volume-varying means to expand. Further, when the displacer approaches the heating portion and blocks the heat transfer from the heating portion to the working fluid, the cooling portion cools the working fluid within the housing to cause the volume-varying means to contract. As the rotatable shaft continuously rotates, the expansion and contraction of the volume-changing means are repeated, and the power-transmitting means transmits mechanical energy, which is generated through the repeated expansion and contraction of the volume-changing means, to the rotatable shaft of the displacer. Therefore, it is possible to continuously obtain rotating power, which is converted from themial energy, from the rotatable shaft. Particularly, since the displacer is rotated in the Stirling engine of the present invention, energy loss due to friction is low and thus efficiency is high as compared with a conventional reciprocating displacer. In the rotary type Stirling engine of the present invention, there may be a plurality of heating and cooling portions, and a plurality of displaces. The number of heating portions may equal to the number of cooling portions and the number of displaces. In this case, the heating and cooling portions may be alternately arranged circumferentially in the housing, so that the displacers secured on the rotatable shaft are rotated and sequentially shield the heating and cooling portions, thereby repeating heat transfer from the heating portions to the working fluid and heat transfer from the working fluid to the cooling portions. Preferably, the rotational shaft is rotatably supported at the center of the housing, the plurality of heating and cooling portions are arranged at an equal interval to be symmetric with one another with respect to a point on a central axis of the rotational shaft, respectively, and the plurality of displacers are arranged at an equal interval to be symmetric with one another with respect to the point on the central axis of the rotational shaft. More preferably, the plurality of heating portions are arranged at a predetermined interval on a side surface of the housing, and the plurality of cooling portions are arranged at a predetermined interval on the other opposite side surface of the housing to be staggered such that the cooling portions do not face the heating portions. Keeping the heating and cooling portions relatively away from each other is advantageous to blocking heat transfer between the heating and cooling portions. It will also be apparent that the heating and cooling portions are not positioned on two side surfaces but may be positioned on a cylindrical surface of the housing or both the two side surfaces and the cylindrical surface. In the rotary type Stirling engine of the present invention, the volume-changing means may comprise a hollow cylinder communicating with the housing, and a power piston installed to reciprocate within the cylinder; and the power-transmitting means may comprise a crank mechanism for transmitting a reciprocating motion of the power piston to the rotational shaft of the displacer while converting the reciprocating motion into a rotating motion. Particularly, if the housing with the working fluid hermetically contained therein has a plurality of circumferentially arranged heating and cooling portions, the working fluid repeats compression and expansion as many times as the number of heating or cooling portions as the displacer is rotated. Therefore, the power piston reciprocates as many times as the number of heating portions when the rotatable shaft makes one revolution, and the power-transmitting means transmits power, which results from the reciprocating motions of the power piston, to the rotatable shaft. The power- transmitting may means comprises a first gear secured on the rotatable shaft, a second gear installed to be rotatable in cooperation with the first gear, and a connecting rod of which one end is pivotably connected to the second gear at a position offset by a predetermined distance from the center of the second gear and the other end is pivotably connected to the power piston. At this time, the ratio of rotation of the second gear to the first gear is set such that the second gear rotates as many revolutions as the number of heating portions when the first gear makes one revolution. According to the present invention, since the plurality of heating and cooling spaces are alternately defined by circumferentially dividing the interior of the housing, the heating and cooling of the working fluid are repeated as many times as the numbers of divided heating and cooling portions as the displacer is rotated. The reciprocating motions of the power piston are continuously converted into rotating motions and transmitted to the rotatable shaft by the power- transmitting means. In particular, if the numbers of circumferentially arranged heating and cooling portions are increased in the Stirling engine of the present invention, it is possible to obtain effects similar to those of a case where mechanical energy converted from a plurality of Stirling engines is simply synchronized and then continuously transmitted to a rotational shaft by using a single power-transmitting means.

Brief Description of Drawings Fig. 1 is a perspective view of a rotary type Stirling engine according to an embodiment ofthe present invention. Fig. 2 is a sectional view ofthe Stirling engine taken along line A- A of Fig. 1. Fig. 3 is an exploded perspective view ofthe Stirling engine shown in Fig. 2. Fig. 4 is a sectional view of a rotary type Stirling engine with heat-radiating fins disposed on a housing thereof according to another embodiment ofthe present invention. Fig. 5 is an exploded perspective view ofthe Stirling engine shown in Fig. 4. Fig. 6 shows schematic views illustrating the operation of the rotary type Stirling engine according to the present invention. Fig. 7 is an exemplary view illustrating how to divide the rotary type Stirling engine according to the present invention. Fig. 8 shows cycle diagrams of a general Stirling engine. Fig. 9 is a schematic view of a conventional Stirling engine.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments of a rotary type Stirling engine according to the present invention will be described in detail. Fig. 1 is a perspective view of a rotary type Stirling engine according to an embodiment of the present invention; Fig. 2 is a sectional view of the Stirling engine taken along line A- A of Fig. 1; and Fig. 3 is an exploded perspective view of the Stirling engine shown in Fig. 2. As shown in Fig. 1, the Stirling engine 100 of this embodiment comprises a hollow cylindrical housing 110 with a working fluid hermetically contained therein; and a rotatable shaft 130 rotatably supported by the housing while penetrating therethrough. Further, the Stirling engine comprises a volume-changing means 120 which communicates with the housing 110 so that the working fluid flows therebetween and of which the volume varies in response to changes in the pressure of the working fluid; and a power- transmitting means 140 for transmitting power generated by expansion and contraction of the volume-changing means 120 to the rotatable shaft 130. Moreover, as shown in Fig. 2, a displacer 150 is fixed to a portion of the rotatable shaft 130 within the housing 110 so that it can be rotated integrally with the rotatable shaft 130 within the housing. As shown in Fig. 3, the housing 110 comprises circular upper and lower side plates 111 and 113, and a hollow cylindrical part 112 coupled to peripheries of the upper and lower side plates 111 and 113 to define a closed space therein. In this embodiment, the interior of the housing 110 is divided into heating zones and cooling zones by quartering the upper and lower side plates 111 and 113 and the cylindrical part 112 so that heating spaces and cooling spaces are alternately arranged adjacent to one another. Thus, the interior of the housing is divided into a pair of heating spaces and a pair of cooling spaces. Particularly, in this embodiment, the upper and lower side plates 111 and 113 and the cylindrical part 112 are quartered circumferentially at an interval of 90 degrees about a central axis, respectively. A first heating space 181 of the housing 110 is defined by an upper plate Ilia, a cylindrical part 112a and a lower plate 113a; and a second heating space 183 is defined by an upper plate 111c, a cylindrical part 112a and a lower plate 113c. Further, a first cooling space 182 of the housing 110 is defined by an upper plate 111b, a cylindrical part 112b and a lower plate 113b; and a second cooling space 184 is defined by an upper plate Hid, a cylindrical part 112d and a lower plate 113d. The lower plates 113a and 113c defining the heating spaces become heating portions by being in contact with external hot portions or including heat sources. The upper plates 111b and Hid defining the cooling spaces become cooling portions by being in contact with external cold portions or including cold sources. Further, the housing 110 has insulation portions 160 disposed at dividing regions on the housing 110 to block heat transfer between the heating portions 113a and 113c and the cooling portions 111b and Hid. Alternatively, remaining portions I lia, 111c, 112a and 112c except for the heating portions 113a and 113c in the heating spaces, and remaining portions 112b, 112d, 113b and 113d except for the cooling portions 111b and 11 Id in the cooling spaces are made of an insulation material. Referring to Fig. 2, the rotatable shaft 130 is rotatably supported by a pair of bearings 131 and 132 in a through-hole llle of the upper plate 111 and a through-hole 113e of the lower plate 113 of the housing 110. Although an end of the rotatable shaft 130 is supported by the bearing in the lower plate 113 while penetrating through the housing 110 in this embodiment, a portion of the rotatable shaft 113 may be accommodated in the housing and the rotatable shaft 113 may be rotatably supported only by the through-hole llle of the upper plate 111 so that the displacer 150 can be disposed and rotated in place. In addition, a flywheel 170 is secured on the rotatable shaft 130 to ensure the stability of rotation of the rotatable shaft. Although the flywheel 170 is secured on the rotatable shaft 130 outside the housing 110 in this embodiment, it may be secured on a proper portion ofthe rotatable shaft 130 within the housing 110, if necessary. Since trie Stirling engine 100 has the two heating regions (heating portions) and the two cooling regions (cooling portions) in this embodiment, two displacers 151 and 152 are provided to block heat transfer between the working fluid and the respective heating and cooling portions upon rotation thereof. Referring to Figs. 2 and 3, each of the displacer 151 and 152 in this embodiment takes the shape of a quartered disk (sector), and an end of the displacer corresponding to an apex of the sector is secured on the rotatable shaft. Although the entire displacers 151 and 152 can be made of an insulation material to block heat transfer to the heating and cooling portions, insulation materials may be attached only to insulation surfaces of the displacers that are in close proximity to the heating portions 113a and 113c and the cooling portions 111b and Hid upon rotation thereof. Further, the displacers are not necessarily a solid type as shown in the figures. Alternatively, the displaces may be constructed such that the working fluid can be accommodated therein so far as they have the insulation surfaces facing the heating and cooling portions. Meanwhile, as for the heating and cooling spaces of the Stirling engine, the same arbitrary numbers of heating spaces H and cooling spaces C are provided and arranged alternately, as shown in Fig. 7. In this embodiment, the interior of the housing 110 is divided to the two heating spaces and the two cooling spaces. However, assuming that the number of divided heating spaces is n, the value of n may be arbitrary determined, if necessary. If the number of heating spaces, n, is 1, a heating space and a cooling space are arranged in the foπn of a semicircle, respectively. If the number of heating spaces, n, is 3, three heating spaces and three cooling spaces are arranged alternately in the housing as shown in the figure. In such cases, the number of displacers also equals to the number of heating spaces. As shown in Fig. 2, the volume-changing means 120 comprises a cylinder 121 communicating with the housing so that the working fluid flows therebetween, and a power piston 122 disposed within the cylinder 121 to reciprocate therein. One side of the cylinder 121 communicates with a through-hole 11 If formed in the upper plate of the housing 110. The power-transmitting means 140 comprises a first gear 141 secured on the rotatable shaft 130, a second gear 142 engaged with the first gear and installed to be rotatable, and a connecting rod 144 of which one end is pivotably connected to the second gear 142 and the other end is pivotably connected to the power piston 121. The end of the connecting rod 144 is pivotably connected through a connection pin 143 to the second gear at a position offset by a predetemiined distance from the center of the second gear. Further, the ratio of rotation of the second gear 142 to the first gear 141 is set such that the second gear makes two revolutions as the first gear makes one revolution. Fig. 4 is a sectional view of a rotary type Stirling engine with heat-radiating fins disposed on a housing thereof according to another embodiment of the present invention; and Fig. 5 is an exploded perspective view ofthe Stirling engine shown in Fig. 4. The Stirling engine of this embodiment is different from the Stirling engine shown in Figs. 2 and 3 in that the heating portions 113a and 113c and the cooling portions 113b and 113d are arranged alternately on the lower plate, and a plurality of heat-radiating fins 114 are fixed to protrude upward in order to improve the efficiency of heat transfer of the heating portions 113a and 113c and the cooling portions 113b and 113d. The heat- radiating fins 114 are arranged to define concentric circles about the center of the housing. Further, the displacer 150 is formed with receiving recesses 153 for receiving the heat- radiating fins 114 to block heat transfer by the heat-radiating fins. The receiving recesses 153 are arranged in the displacer 150 to define concentric circles at the same intervals as the heat-radiating fins so that they cannot interfere with the heat-radiating fins upon rotation ofthe displacer. h a case where the heating portions and the cooling portions are separately formed in the upper and lower plates, the respective heat-radiating fins can also be separately airanged depending on the positions ofthe heating and cooling portions. The operation of the Stirling engine of this embodiment will be described below with reference to Fig. 6. When the displacer 150 is positioned between the heating spaces and the cooling spaces, the power piston is positioned at the bottom dead point B, as shown in Fig. 6 (a). However, when the displacer is slightly rotated in a direction designated by an arrow, the area of the heating portions becomes larger than that of the cooling portions, thereby heating the working fluid. The pressure of the heated working fluid increases and is exerted on the power piston 122 to raise the power piston, thereby maintaining an equilibrium state. The raise of the power piston 122 is converted through the power- transmitting means 140 into rotating power that in turn is transmitted to the rotatable shaft 130. When the displacer 150 is further rotated and positioned in the cooling spaces as shown in Fig. 6 (b), the displacer 150 fully shields the cooling portions so that heating performed by the heating portions is maximized. The working fluid continuously expands and raises the power piston 122. Therefore, the rotating power is continuously transmitted through the power- transmitting means 140 to the rotational shaft. The process from the state of Fig. 6 (a) to the state of Fig. 6 (b) becomes a heating process. When the displacer 150 is further rotated in the direction designated by the arrow so that it is moved from the state of Fig. 6 (b) to the state of Fig. 6 (c), the area of the heating portions is still larger than that of the cooling portions but continuously decreases. Thus, the working fluid is continuously heated and expands and the power piston 122 reaches the top dead point U. The process from the state of Fig. 6 (b) to the state of Fig. 6 (c) becomes an expansion process. When the displacer 150 is in the state shown in Fig. 6 (c), the area of the cooling portions equals to that of the heating portions. Since the displacer 150 shields the heating portions and reveals the cooling portions until it is further rotated in the direction designated by the arrow from the state of Fig. 6 (c) and is in the state of Fig. 6 (d), the working fluid is cooled. The pressure of the cooled working fluid drops to maintain an equilibrium state, and the power piston 122 is lowered from the top dead point in response to the pressure drop. The process from the state of Fig. 6 (c) to the state of Fig. 6 (d) becomes a cooling process. In the state of Fig. 6 (d), the heating portions are fully shielded so that the working fluid is cooled and compressed. The working fluid is continuously compressed until the area of the heating portions equals to that of the cooling portions as the displacer 150 is continuously rotated, and the power piston reaches the bottom dead point. The process from the state of Fig. 6 (d) to the state of Fig. 6 (a) (actually, the orientation ofthe displacer 150 in this state is different from that shown in Fig. 6 (a) since the displacer has been rotated by 180 degrees) becomes a compression process. As described above, the Stirling engine of this embodiment performs the cycle, which consists of the heating-expansion-cooling-compression processes, twice while the displacer 150 secured on the rotatable shaft 130 makes one revolution. Therefore, the power piston 122 reciprocates twice within the cylinder 121. The reciprocating motion of the power piston 122 is converted into the rotating motion of the rotatable shaft 130 through a crank mechanism comprising the first gear 141 secured on the rotational shaft, the second gear 142 installed to be rotatable in cooperation with the first gear, and the connecting rod 144 of which one end is pivotably connected to the second gear 142 and the other end is pivotably connected to the power piston 121. Particularly, the two reciprocating passes of the power piston 122 are accurately converted into the rotating power so that the rotatable shaft makes one revolution by means of the ratio of rotation of the first gear to the second gear, which is set such that the first gear makes one revolution as the second gear makes two revolutions. According to the present invention, there is provided a rotary type Stirling engine with a rotating displacer, wherein energy loss due to inertia and friction of a displacer is reduced as compared with a conventional reciprocating type Stirling engine, and high power can be output even with a small difference in temperature. According to the present invention, there is provided a rotary type Stirling engine with a plurality of heating and cooling spaces defined by circumferentially dividing the interior of a housing of the Stirling engine. The Stirling engine comprises a power- transmitting means for transmitting power, which is generated through heating and cooling processes of a working fluid repeated as many times as the number of divided heating spaces as a displacer makes one revolution, to a rotational shaft while continuously converting the power into a rotating motion. Thus, with the Stirling engine of the present invention, it is possible to obtain effects similar to those of a case where mechanical energy converted from a plurality of Stirling engines is simply synchronized and then continuously transmitted to a single rotational shaft by using a single power-transmitting means. It is intended that the embodiments of the present invention described above and illustrated in the drawings should not be construed as limiting the technical spirit of the present invention. The scope of the present invention is defined only by the appended claims. Those skilled in the art can make various changes and modifications thereto without departing from the spirit. Therefore, various changes and modifications obvious to those skilled in the art will fall within the scope ofthe present invention.

Claims

1. A rotary type Stirling engine, comprising: a hollow cylindrical housing with a compressible working fluid hermetically contained therein, the housing having a hot heating portion for heating the working fluid and a cold cooling portion for cooling the working fluid; a rotatable shaft rotatably supported by the housing while a portion thereof is accommodated within the housing; a displacer secured on the portion of the rotatable shaft accommodated within the housing so as to block heat transfer from the heating portion to the working fluid or from the working fluid to the cooling portion upon rotation ofthe displacer; a volume-changing means communicating with the housing so that the working fluid flows therebetween, and having a volume varying in response to changes in the pressure ofthe working fluid; and a power-transmitting means for transmitting power to the rotatable shaft, the power being generated through repeated expansion and contraction of the volume- changing means in response to the changes in the pressure of the working fluid upon rotation ofthe displacer.

2. The rotary type Stirling engine according to Claim 1, wherein the housing has a plurality of heating and cooling portions, the number of heating portions equals to the number of cooling portions, and the heating and cooling portions are alternately arranged circumferentially; and the displacer comprises a plurality of displaces, the number of displaces equals to the number of heating portions, and the displacers are secured circumferentially on the rotational shaft at intervals corresponding to those of the plurality of heating portions.

3. The rotary type Stirling engine according to Claim 2, wherein the rotational shaft is rotatably supported at the center ofthe housing, the plurality of heating and cooling portions are arranged at an equal interval to be symmetric with one another with respect to a point on a central axis of the rotational shaft, respectively, and the plurality of displacers are arranged at an equal interval to be symmetric with one another with respect to the point on the central axis ofthe rotational shaft.

4. The rotary type Stirling engine according to Claim 3, wherein the plurality of heating portions are arranged at a predetermined interval on a side surface of the housing, and the plurality of cooling portions are arranged at a predetermined interval on the other opposite side surface of the housing to be staggered such that the cooling portions do not face the heating portions.

5. The rotary type Stirling engine according to any one of Claims 1 to 4, wherein the volume-changing means comprises a hollow cylinder communicating with the housing, and a power piston installed to reciprocate within the cylinder; and the power-transmitting means comprises a crank mechanism for transmitting a reciprocating motion of the power piston to the rotational shaft of the displacer while converting the reciprocating motion into a rotating motion.

6. The rotary type Stirling engine according to Claim 5, wherein if there are a plurality of heating and cooling portions, the power- transmitting means transmits the power to the rotational shaft in such a manner that the power piston reciprocates as many times as the number of heating portions when the rotational shaft makes one revolution.

7. The rotary type Stirling engine according to any one of Claims 1 to 4, wherein the volume-changing means comprises a hollow cylinder communicating with the housing, and a power piston installed to reciprocate within the cylinder; and the power-transmitting means comprises a first gear secured on the rotatable shaft, a second gear installed to be rotatable in cooperation with the first gear, and a connecting rod of which one end is pivotably connected to the second gear at a position offset by a predetermined distance from the center of the second gear and the other end is pivotably connected to the power piston.

8. The rotary type Stirling engine according to Claim 7, wherein if there are a plurality of heating and cooling portions, the ratio of rotation of the second gear to the first gear is set such that the second gear rotates as many revolutions as the number of heating portions when the first gear makes one revolution.