JP2005076557A - Stirling engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To promote size reduction and high output of a Stirling engine. <P>SOLUTION: A space above a piston 23 of a high-temperature side cylinder 21 and a space above a piston 24of a low-temperature side cylinder 22 communicate with each other through a heater 27, regenerative heat exchanger 28, and a working gas passage 30 equipped with a cooler 29. A space below the piston 23 and a space below the piston 24 communicate with each other through a heater 31, a regenerative heat exchanger 32, and a working gas passage 34 equipped with a cooler 33. The lower ends of the pistons 23, 24 are connected, with a rotational phase difference of a Stirling cycle, to a rotating shaft 36 protruded from both sides of a generator 35 through a crank mechanism. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technique for downsizing a Stirling engine and improving output performance.

Conventionally, Stirling engines can obtain high thermal efficiency equivalent to the Carnot cycle in principle, and are external combustion engines and can use a wide variety of heat sources {particularly exhaust heat that is difficult to transport (store)}. In view of the point that noise is low because it does not involve explosive combustion like an internal combustion engine, the occurrence of incomplete combustion is less than that of an internal combustion engine, and it is advantageous for emission of exhaust harmful components, etc. As a new power source, various types have been proposed. For example, the applicant of the present application has also proposed a Stirling engine that improves output and fuel consumption (see Patent Document 1).
JP-A-10-318042 (Japanese Patent No. 3134115)

However, the Stirling engine still has room for improvement in terms of compactness, high output, and low vibration.
The present invention has been made paying attention to such a conventional problem, and an object thereof is to provide a Stirling engine that is more compact, has a high output, and has little vibration.

  For this reason, the present invention forms a pair of spaces with variable volumes on both sides of the pistons in each cylinder by inserting the pistons into a pair of cylinders. The regenerative heat exchanger and the cooler communicate with each other, and a working gas is sealed in each of the pair of communication spaces, and each pair of pistons is connected to each of the pair of pistons to convert a reciprocating motion into a rotational motion. The end portions of the reciprocating / rotating motion converting member are connected to each other with a rotational phase difference via a rotating shaft of a generator, and the pair of pistons are driven by a pressure change of working gas acting on both sides, It was set as the structure which rotationally drives the rotating shaft of the said generator through a pair of reciprocating / rotational motion conversion member.

  In this way, it is possible to promote as much as possible the improvement in power generation output due to compactness and high output, and vibration can be reduced.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows a cross-sectional view of the mechanism of a Stirling engine according to the present invention.
In the figure, the main body of the Stirling engine 1 is configured by connecting an upper casing 11 and a lower casing 12. In the upper casing 11, a high temperature side cylinder 21 and a low temperature side cylinder 22 are formed upright in parallel, and pistons 23, 24 are fitted in the cylinders 21, 22 so as to be freely slidable in the vertical direction. Output rods 25 and 26, which are reciprocating / rotational motion conversion members, are connected to the lower ends of the pistons 23 and 24. The lower ends of the output rods 25 and 26 are the bottom walls of the cylinders 21 and 22 and the lower casing 12 respectively. It penetrates the upper wall freely in the vertical direction and extends downward.

Here, although not shown in the figure, the space between the pistons 23 and 24 and the peripheral walls of the cylinders 21 and 22 is kept airtight via a piston ring fitted into the pistons 23 and 24.
The space above the piston 23 of the cylinder 21 and the space above the piston 24 of the cylinder 22 are provided with a heater (heater; H) 27, a regenerative heat exchanger (RG) 28, and a cooler (cooler; C) 29. Via the working gas passage 30, the working gas is connected in fluid communication with little resistance. Similarly, the space below the piston 23 of the cylinder 21 and the space below the piston 24 of the cylinder 22 are provided with a heater (heater; H) 31, a regenerative heat exchanger (RG) 32, and a cooler (cooler; C) 33. Through the intervening working gas passage 34, the working gas is connected in a free flowing manner with almost no resistance.

  The lower casing 12 is formed in a substantially cylindrical shape, and a generator that is a load driven by the engine is stored and held in the center. The generator 35 has both end portions 36a and 36b of the rotating shaft 36 protruding from both sides of the housing. The rotating phase difference between the both ends 36a and 36b with respect to the rotating shaft 32 via the circular plates 37 and 38 is provided. Eccentric shafts 39 and 40 are connected to each other, and bearing rollers 41 and 42 are rotatably inserted and held on the eccentric shafts 39 and 40, respectively.

The lower ends of the two output rods 25 and 26 are long in a direction perpendicular to the direction in which the output rods 25 and 26 operate (in the horizontal direction when the output rods are arranged to move up and down as shown). Engagement members 43 and 44 having oval long holes 43a and 44a are connected.
Then, the eccentric shafts 39 and 40 are engaged with the long holes 43a and 44a via the bearing rollers 41 and 42, respectively.

Here, the rotational phase difference θ is set so that the eccentric shaft 39 advances from the eccentric shaft 40 by about 90 ° with respect to the rotational direction of the rotary shaft 36.
FIG. 2 illustrates the operation of the Stirling engine.
As described above, there is no flow resistance for the movement of the working gas, the upper space of the two cylinders 22 and 24, the inner space of the heater 27, the regenerative heat exchanger 28, the cooler 29, and the working gas passage 30; The pressure in the sealed whole space (hereinafter referred to as the working space A) is uniform, and the lower space of the two cylinders 22 and 24, the heater 31, the regenerative heat exchanger 32, the cooler 33, and the operation The pressure in the entire sealed space (hereinafter referred to as the working space B), which is the sum of the internal space of the gas passage 34, is uniform, and the rotating shaft is in a state where the piston 23 is advanced by 90 ° with respect to the piston 24. Assume that 36 rotates in the direction shown.

a (piston 23 is top dead center) to b (piston 24 is top dead center)
The piston 23 is lowered and the piston 24 is raised. During this time, the volume of the entire upper working space A is almost constant (exactly, the volume is minimum at the intermediate position), but the space volume on the piston 24 side is reduced and cooled by the cooler 27. After the working gas is heat-exchanged by the regenerative heat exchanger 26, it is heated through the heater 25 and flows into the space on the piston 23 side, so the amount of heat of the working gas increases and the pressure increases. In other words, it is a process close to isovolume heating. On the other hand, in the lower working space B, the overall volume is almost constant (exactly, the volume is maximum at the intermediate position), but the space volume on the piston 23 side is reduced and heated by the heater 31. After the working gas that has been subjected to heat exchange in the regenerative heat exchanger 32, it is cooled through the cooler 33 and flows into the space on the piston 24 side, so the amount of heat of the working gas is reduced and the pressure is reduced. That is, it is a process close to the isovolume cooling (exhaust heat).

bc (piston 23 is bottom dead center)
Both pistons 23 and 24 descend. The working space A increases in volume and decreases in pressure, and the working space B decreases in volume and increases in pressure.
cd (piston 24 is bottom dead center)
The piston 23 is raised and the piston 24 is lowered. During this time, the above-described a and b are the effects in which the actions of the working space A and the working space B are interchanged. In other words, the working space A has an effect close to isovolume cooling, and the working space B has an effect close to isometric heating.

d ~ a
Both pistons 23 and 24 rise. During this time, the above-described b to c are effects in which the actions of the working space A and the working space B are interchanged. That is, the volume of the working space A decreases and the pressure increases, and the volume of the working space B increases and the pressure decreases. The working space A produces an action close to isovolume cooling, and the working space B produces an action close to isovolume heating. The working space is reduced and the pressure is increased.

  FIG. 3 shows a pressure-total volume (p-V) diagram when the rotating shaft 36 of the generator makes one revolution (the symbols a to d without parentheses are the working space A, and the symbols a to d with parentheses are Therefore, positive work is performed, and both sides of the pistons 23 and 24 are compared with a Stirling engine in which the working space is provided only on one side of the piston. The differential pressure is doubled and the drive output is doubled.

As described above, the double-acting type Stirling cycle can achieve a high output with a small size. In addition, since the operation of two cycles is performed with one rotation, the rotation is smooth and there is little vibration.
Further, since the output shaft of the Stirling engine is constituted by the rotating shaft 36 of the generator as a load driven by the Stirling engine, further downsizing and higher output are promoted. In other words, a Stirling engine is configured by integrating a generator, which is a load, and is driven by connecting a rotating shaft of a load (generator, etc.) outside the output shaft (crankshaft) of a conventional Stirling engine. Compared with what to do, a shaft coupling etc. become unnecessary and it can achieve a significant compactness as a usage form which drives a generator with a Stirling engine.

Further, conventionally, the engine output shaft and the rotating shaft of the generator as a load are each supported by a bearing, whereas in the present invention, only the rotating shaft of the generator that also serves as the engine output shaft needs to be supported by the bearing. The number of bearings can be greatly reduced, the mechanical loss is reduced, and the performance is improved.
In addition, by configuring the engine output shaft as a rotating shaft of a generator, the manufacturing cost can be reduced in combination with the fact that the number of the bearings can be greatly reduced, and the driving efficiency and thus the running cost can be improved by shortening the drive transmission path. .

On the other hand, when viewed from the side of the generator 35 that is a load, a generator 35 that is a rotating mass is arranged in the center of the two pistons 23 and 24, and the rotational shaft 36 is driven symmetrically. Therefore, as compared with the conventional configuration in which one end of the generator rotating shaft is connected to the outside of the engine and driven, the rotational performance is significantly stabilized.
Even though the generator is integrated, the generator can be easily replaced.In addition to replacement at the time of failure, it is also possible to select and replace generators with different outputs depending on the usage situation. Easy to do.

  The Stirling engine is a reversible mechanism, and it is known that the Stirling engine can be operated as a heat pump to obtain heat output by driving the Stirling engine on the contrary using the generator as an electric motor. The present invention is also effective when the Stirling engine is used as a heat pump.

Sectional drawing of the Stirling engine concerning this invention. The figure which shows the Stirling cycle operation | movement of embodiment same as the above. The PV diagram of the Stirling cycle of embodiment same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stirling engine 21 High temperature side cylinder 22 Low temperature side cylinder 23, 24 Piston 25, 26 Output rod 35 Generator 36 Rotating shaft 27, 31 Heater 28, 32 Regenerative heat exchanger 29, 33 Cooler

Claims (1)

  Pistons are respectively fitted into a pair of cylinders to form a pair of spaces with variable volumes on both sides of the pistons in each cylinder, and the same side spaces in the cylinders are respectively heated, regenerative heat exchangers, Each pair of reciprocating motion / rotational motion conversion that communicates via a cooler, encloses a working gas in each of the pair of communication spaces, and is connected to each of the pair of pistons to convert a reciprocating motion into a rotational motion. The ends of the members are connected to each other through a rotating shaft of a generator with a rotational phase difference, and the pair of pistons are driven by a change in pressure of the working gas acting on both sides, and the pair of reciprocating / rotating operations A Stirling engine characterized in that the rotating shaft of the generator is rotationally driven through a dynamic conversion member.

Images