Patent Grant
8938942
This application is the U.S. National Phase under 35 U.S.C. §371 of International Application PCT/JP2010/059228, filed Jun. 1, 2010. The International Application was published under PCT Article 21(2) in a language other than English.
The present invention relates to an external-combustion, closed-cycle thermal engine having a simple structure and allowing for easy operation and maintenance.
The Stirling engine, which is quiet and low-pollution and allows for effective utilization of otherwise wasted energy regardless of the type of heat source, is an external-combustion thermal engine which is recognized as a prominent thermal engine for the future, and under which category various types of engines are being researched and developed.
The Stirling engine obtains motive power by heating and cooling the working gas filled in the gas chamber to cause the gas to expand and contract.
The conventional displacer-type Stirling engine obtains motive power by heating and cooling the working gas moved back and forth between the heating part and cooling part by means of the displacer, to cause the gas to expand and contract, and thereby operate a power piston. The displacer is constituted to operate in conjunction with the power piston with a phase.
The conventional Stirling engines are classified into three types—α, β, and γ—depending on the layout of pistons, cylinders, etc. Operations of these three types of engines are described in detail in Patent Literature 1.
With the aforementioned conventional Stirling engines, however, working gas is simultaneously compressed and decompressed in the gas chamber, heater and cooler. To be specific, working gas in the cooler must also be compressed to compress the gas chamber in the heating period, and working gas in the heater must also be decompressed to decompress the gas chamber in the cooling period. For this reason, the volume of the heater or cooler becomes larger relative to the volume of the gas chamber, which reduces the engine efficiency. Accordingly, the heater and cooler must be made smaller to raise the engine efficiency.
However, operating the engine requires that the necessary amount of heat be taken in and exhausted, for which the heater and cooler must have sufficient capacities. To make the heater smaller but still provide sufficient capacity, the thickness can be reduced or the heating temperature can be raised to increase the amount of heat conducted per unit area. However, these measures require precision work and adoption of expensive heat-resistant metal and present a problem of promoted corrosion of the heater due to high temperature.
In addition, the heater is not used in the cooling period, which results in a lower heater efficiency over the entire period, and because the external heat added to the heater is wasted, the utilization efficiency drops. The same goes with the cooler in the heating period.
Patent Literature 1: Japanese Patent Laid-open No. 2006-275018
In light of the conventional technology mentioned above, the object of the present invention is to provide an external-combustion, closed-cycle thermal engine whose heater or cooler volume does not affect engine efficiency and which can be designed and produced under various conditions.
The invention according to Embodiment 1 realizes an external-combustion, closed-cycle thermal engine whose heater or cooler volume does not affect engine efficiency and which can be designed and produced under various conditions, wherein such engine comprises:
The invention according to Embodiment 2 is an external-combustion, closed-cycle thermal engine according to Embodiment 1, characterized in that the on-off valves are three-way valves. A three-way valve is defined as a switching valve having three branched flow paths to allow for selective connection of a fluid body entering from one branch to one of the remaining two branched flow paths, or selection of one of two branched flow paths to be connected to the remaining flow path.
The invention according to Embodiment 3 is an external-combustion, closed-cycle thermal engine according to Embodiment 1, characterized in that the on-off valves provided in the flow path connecting the gas chamber to the inlet side of the heater and flow path connecting the outlet side of the cooler to the gas chamber, are check valves.
The invention according to Embodiment 4 is an external-combustion, closed-cycle thermal engine according to any one of Embodiments 1 to 3, characterized in that the operation body is a piston. If the operation body is a piston, the gas chamber is defined as a cylinder and multiple gas chambers as multiple cylinders.
The invention according to Embodiment 5 is an external-combustion, closed-cycle thermal engine according to any one of Embodiments 1 to 3, characterized in that the operation body is a reciprocal flow turbine. A reciprocal flow turbine is a device that generates rotational torque in the same direction even when the flow direction of working gas reverses.
The invention according to Embodiment 6 is an external-combustion, closed-cycle thermal engine according to any one of Embodiments 1 to 5, characterized in that multiple sealed gas chambers and operation bodies are provided to share the heater and cooler.
The invention according to Embodiment 7 is an external-combustion, closed-cycle thermal engine according to any one of Embodiments 1 to 4 and 6, characterized in that the pistons provided in the multiple sealed gas chambers (multiple cylinders) have a shared crank chamber.
The invention according to Embodiment 8 is an external-combustion, closed-cycle thermal engine according to any one of Embodiments 1 to 4, 6 and 7, characterized in that flow paths that connect the inlet side and outlet side of the heater, respectively, and flow paths that connect the inlet side and outlet side of the cooler, respectively, are provided to a chamber A and a chamber B created by dividing the gas chamber by the piston.
The invention according to Embodiment 9 is an external-combustion, closed-cycle thermal engine according to any one of Embodiments 1 to 3, 5 and 6, characterized in that flow paths that connect the inlet side and outlet side of the heater and flow paths that connect the inlet side and outlet side of the cooler are provided to each chamber created by dividing the gas chamber by one or multiple reciprocal flow turbines, respectively.
With the external-combustion, closed-cycle thermal engine proposed by the present invention, the cooler is sealed by the on-off valves and therefore working gas in the cooler is not compressed and remains at low temperature and low pressure when the gas chamber is heated, while the heater is sealed by the on-off valves and therefore working gas in the heater is not decompressed and remains at high temperature and high pressure when the gas chamber is cooled, and temperature/pressure changes only occur in the working gas in the gas chamber, and accordingly, unlike the conventional Stirling engine, no wasteful energy is consumed to compress or decompress the working gas in the heater and cooler, regardless of the sizes of the heater and cooler. This improves the heating and cooling efficiencies and achieves a higher engine efficiency than the conventional Stirling engine. Also, temperature/pressure in the gas chamber can be rapidly changed by switching the on-off valves, to increase the engine output.
When the gas chamber is heated, the cooler is sealed by the on-off valves and therefore working gas in the cooler can be cooled continuously in an effective manner, and when the gas chamber is cooled, the heater is sealed by the on-off valves and therefore working gas in the heater can be heated continuously in an effective manner, which allows both the heater and cooler to operate effectively during the entire period and also increases the utilization efficiencies of the heat source and cold heat source.
As explained above, since the volumes of the heater and cooler including flow paths no longer affect efficiency, the flow paths between the heater/cooler and engine can be made longer, allowing the heater and cooler to be installed away from the engine, which in turn ensures flexibility of equipment layout as well as effective utilization of existing waste heat sources, etc., at positions where the engine is difficult to install.
In addition, the heater and cooler can be increased in size to provide a larger heat conduction area, thereby ensuring a sufficient amount of heat to be conducted even at a small temperature difference, which in turn allows for effective utilization of low-temperature heat sources such as waste heat, and also makes the design conditions for the heater less strict so that the best material, structure, workings, etc., can be selected for the heater according to the purpose.
Rare helium need not be used for the working gas, and the working gas can be nitrogen, air, etc. Also, use of carbon dioxide, xenon or other gas of high specific gravity allows the reciprocal flow turbine to be made smaller.
In addition, no displacer is used, which means that heat-insulation material can be provided in the gas chamber and consequently the amount of heat dissipation through the exterior of the gas chamber can be reduced to improve thermal efficiency, while the ability to keep the exterior of the gas chamber at low temperature eliminates the need to use expensive heat-resistant alloys.
By using three-way on-off valves and providing them on the inlet side and outlet side of the heater and cooler, respectively, the number of flow paths to the gas chamber can be reduced from four to two to simplify the structure.
Furthermore, using check valves that automatically actuate upon pressure change for the on-off valves on the inlet side of the heater and outlet side of the cooler eliminates the need for human operation and simplifies the control operation.
According to the present invention, an external-combustion, closed-cycle thermal engine whose operation body is a piston or reciprocal flow turbine can be provided.
Also with the present invention, the working gas in the heater remains at high temperature and high pressure, while the working gas in the cooler remains at low temperature and low pressure, throughout the entire cycle, and therefore if multiple sealed gas chambers and operation bodies are provided to achieve a multi-cylinder configuration, one large heater and one large cooler can be provided and shared by the multiple cylinders. Accordingly, the heater/cooler structure can be significantly simplified compared to the conventional multi-cylinder Stirling engine that requires one heater and one cooler for each cylinder.
If the present invention is applied as a multi-cylinder external-combustion, closed-cycle thermal engine having multiple sealed gas chambers and using pistons as operation bodies, one crank chamber can be shared and each cylinder piston can be actuated at an equal phase difference of 360° in total, so as to keep the total volume and pressure of the shared crank chamber and spaces below the pistons in the cylinder chambers constant, thereby preventing change in the force applied to the back of each piston and ensuring smooth piston operation.
The star, horizontal opposing, and V layouts are supported, among others.
Flow paths are provided that connect the inlet side and outlet side of the heater, respectively, and inlet side and outlet side of the cooler, respectively, to a chamber A and a chamber B created by dividing the cylinder by the piston, so that chamber B becomes low in temperature and low in pressure when chamber A is set to high temperature and high pressure through operations of the on-off valves, while chamber B becomes high in temperature and high in pressure when chamber A is set to low temperature and low pressure, thereby allowing a greater pressure difference to be applied to the piston and ensuring high output with a small engine.
By providing flow paths that connect the inlet side and outlet side of the heater and inlet side and outlet side of the cooler, to each chamber created by dividing the cylinder by one or multiple reciprocal flow turbines, respectively, and allowing the adjacent chambers to have the opposite processes of heating and cooling through operations of the on-off valves, as the number of reciprocal flow turbines increases, a greater pressure difference can be applied to each reciprocal flow turbine, thereby ensuring high output with a small engine.
Specific modes for carrying out the present invention are explained in detail by referring to the drawings.
In this figure, a bulkhead 110 and a cylinder 111 are provided below a gas chamber 101, and a piston 112 is provided on the inside of the cylinder 111. Reference numeral 113 represents a crank, 114 represents a rotational shaft, and 115 represents a flywheel. The crank 113, rotational shaft 114 and flywheel 115 are stored in a sealed crank chamber 116. These components are conventionally known and therefore not explained in details. A fan 120 is provided at the top edge of the gas chamber 101, and a chamber 130 is formed downstream of the fan 120. A motor (not illustrated) that drives the fan 120 is provided at the upper part of the gas chamber 101, and the fan 120 is secured to a drive shaft 121. Reference numeral 140 represents a heater whose one end is connected to the chamber 130 via a flow path on hot-gas inlet side 141 and whose other end is connected to the lower part of the gas chamber via a flow path on hot-gas outlet side 142. Reference numeral 150 represents a cooler whose one end is connected to the chamber 130 via a flow path on cool-gas inlet side 151 and whose other end is connected to the lower part of the gas chamber 101 via a flow path on cool-gas outlet side 152. Reference numeral 143 represents an on-off valve provided in the flow path on hot-gas inlet side 141, 144 represents an on-off valve provided in the flow path on hot-gas outlet side 142, 153 represents an on-off valve provided in the flow path on cool-gas inlet side 151, and 154 represents an on-off valve provided in the flow path on cool-gas outlet side 152.
The positions of on-off valves 143, 144, 153, 154 indicated by solid lines in
The operation of the above is as follows. First, the fan 120 causes the working gas such as nitrogen gas in the gas chamber to flow in the direction of the arrow into the chamber 130, and because the on-off valves 143, 144 are open and on-off valves 153, 154 are closed, the flow of working gas enters the flow path on hot-gas inlet side 141, passes the heater 140, and flows into the lower part of the gas chamber from the flow path on hot-gas outlet side 142, as shown by the arrows, as a result of which the working gas in the gas chamber is heated and becomes high in temperature and pressure and expands, to push down the piston 112 and turn the rotational shaft 114 via the crank 113. When the gas chamber is in the heating process, the on-off valves 153, 154 remain closed and working gas in the cooler 150 continues to be cooled. Next, the on-off valve 144 in the flow path on hot-gas outlet side 142 and on-off valve 143 in the flow path on hot-gas inlet side 141 are controlled to the closed positions indicated by broken lines, while the on-off valve 154 in the flow path on cool-gas outlet side 152 and on-off valve 153 in the flow path on cool-gas inlet side 151 are controlled to the open positions indicated by broken lines, to cause the high-temperature, high-pressure working gas in the gas chamber to flow into the cooler 150, upon which the pressure in the gas chamber drops rapidly. When the pressure in the cooler 150 becomes roughly equivalent to the pressure in the gas chamber, the working gas circulates from the gas chamber to the fan 120, to the flow path on cool-gas inlet side 151, to the cooler 150, to the flow path on cool-gas outlet side 152, and to the gas chamber, and as the working gas in the gas chamber is cooled and decompressed and contracts, the piston 112 is pushed up by the pressure of the gas in the crank chamber 116 (since the gas chamber is charged with high pressure, this pressure is much higher than the atmospheric pressure even in the cooling period), and the rotational shaft 114 turns via the crank 113. When this gas chamber is in the cooling process, the on-off valves 143, 144 remain closed and working gas in the heater 140 continues to be heated. When the heating process starts at the gas chamber, therefore, the low temperature and low pressure in the gas chamber that has just completed the cooling process can be raised rapidly by switching the on-off valves 143, 144, 153, 154. Through repeated switchings of the on-off valves 143, 144, 153, 154 between the open position and closed position as described above, the working gas in the gas chamber is heated/cooled and compressed/decompressed repeatedly.
While the heater and cooler of the conventional Stirling engine operate only during partial periods, the aforementioned heater 140 and cooler 150 operate effectively over the entire period to improve performance as described above. Also, the amount of heat required for heating, and amount of cold heat required for cooling are effectively utilized throughout the entire period without any part of the heat or cold heat being wasted as is the case with the conventional Stirling engine, which improves the thermal efficiency of the system.
In this figure, the components common to those in
The operation of the above is roughly the same as that illustrated in
In this figure, the chamber 130 at the upper part of the gas chamber 101 has an opening 310 that connects to a flow path 311 and branches at a three-way valve 320 provided at the end of the flow path 311, to be selectively guided to the flow path on hot-gas inlet side 141 or flow path on cool-gas inlet side 151. The flow path on hot-gas outlet side 142 of the heater 140 or flow path on cool-gas outlet side 152 of the cooler 150 is selectively connected to a flow path 331 via a three-way valve 321, and the flow path 331 is connected to an opening 330 provided at the lower part of the gas chamber 101. The flow paths 311, 331 may be shortened or not provided at all, with the three-way valves 320, 321 provided at the openings 310, 330.
In the foregoing, the on-off valves 143, 153 as described in
The three-way valves 320, 321 indicated by solid lines in
In the heating process, the check valve 145 opens automatically due to the pressure of the fan 120 when the pressure in the gas chamber becomes roughly equivalent to the pressure in the heater 140. At this time, since the gas chamber is charged with high pressure, the working gas does not enter the cooler 150 from the check valve 155 provided in the flow path on cool-gas outlet side 152. In the cooling process, the check valve 155 opens automatically due to the pressure of the fan 120 when the pressure in the gas chamber becomes roughly equivalent to the pressure in the cooler 150. At this time, since the gas chamber is charged with low pressure, the working gas does not enter the heater 140 from the check valve 145 provided in the flow path on hot-gas inlet side 141.
The above structure simplifies the control and structure of the external-combustion, closed-cycle thermal engine.
In this figure, multiple gas chambers (1) to (4) are placed to achieve a multi-cylinder configuration, where the flow path on hot-gas inlet side 141 and flow path on hot-gas outlet side 142 connecting to each gas chamber (cylinder) share one heater 140, while the flow path on cool-gas inlet side 151 and flow path on cool-gas outlet side 152 connecting to each gas chamber share one cooler 150. Reference numeral 410 represents a heater header that branches the flow path on hot-gas inlet side 141 connecting to each gas chamber (cylinder), while 420 represents a heater header that aggregates the flow path on hot-gas outlet side 142 connecting to each gas chamber (cylinder). Reference numeral 430 represents a cooler header that branches the flow path on cool-gas inlet side 151 connecting to each gas chamber (cylinder), while 440 represents a cooler header that aggregates the flow path on cool-gas outlet side 152 connecting to each gas chamber (cylinder). Reference numeral 450 represents a fan provided in a flow path 421 between the heater 140 and heater header 420, while 460 represents a fan provided in a flow path 461 between the cooler 150 and cooler header 440.
The heater 140 is constantly kept at high temperature and high pressure, while the cooler 150 is constantly kept at low temperature and low pressure, and therefore the operation described in detail in
In this figure, the crank chambers 116 provided in the gas chambers (1) to (4) are interconnected to form one crank chamber 470. The rotational shafts 114 connecting to each crank 113 share a center shaft. As shown in this figure, the pistons 112 operate at an equal phase difference of 360° in total, to keep the space volume of the crank chamber 470, including the volume below the piston in each gas chamber (cylinder), constant.
In this figure, the piston 112 divides the gas chamber 101 into gas chamber A and gas chamber B, and openings 310, 330 are provided in each gas chamber which connect, via three-way valves 320, 321, to the flow path on hot-gas inlet side 141, flow path on hot-gas outlet side 142, flow path on cool-gas inlet side 151 and flow path on cool-gas outlet side 152, and then to the heater headers 410, 420 and cooler headers 430, 440, to constitute the closed-cycle circuit of working gas that connects to the heater 140 and cooler 150. A fan 450 is provided at the end of the heater header 420 to constantly circulate high-temperature, high-pressure working gas, while a fan 460 is provided at the end of the cooler header 440 to constantly circulate low-temperature, low-pressure working gas.
The three-way valves 321, 320 indicated by solid lines in
The three-way valves 321, 320 indicated by solid lines in
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2010/059228 | 6/1/2010 | WO | 00 | 12/21/2012 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2011/151888 | 12/8/2011 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3751904 | Rydberg | Aug 1973 | A |
| 3767325 | Schuman | Oct 1973 | A |
| 4327550 | Knoos | May 1982 | A |
| 4367625 | Vitale | Jan 1983 | A |
| 4622813 | Mitchell | Nov 1986 | A |
| 6470683 | Childs et al. | Oct 2002 | B1 |
| 7603858 | Bennett | Oct 2009 | B2 |
| Number | Date | Country |
|---|---|---|
| 1981-167760 | Dec 1981 | JP |
| S61-500272 | Feb 1986 | JP |
| 2000-265853 | Sep 2000 | JP |
| 2006-275018 | Oct 2006 | JP |
| Entry |
|---|
| A Notification of First Office Action with Search Report issued by the State Intellectual Property Office of China, mailed May 14, 2014, for Chinese counterpart application No. 2010800067011.1. |
| Number | Date | Country | |
|---|---|---|---|
| 20130174532 A1 | Jul 2013 | US |
