JPS5985460A - Stirling engine - Google Patents

Abstract

PURPOSE:To improve the coefficient of heat transfer of the heating pipe of a Stirling engine, make the pipe compact and reduce the engine's unavailable volume to heighten the compression ratio, by providing a spiral slender member around the heating pipe. CONSTITUTION:The working fluid of a Stirling engine is caused to flow through a regenerator 6, a heating pipe 7 and the high-temperature part 4 of a cylinder chamber. Heat exchange between the working fluid in the heating pipe 7 and combustion gas shown by an arrow A in the drawing is effected. A spiral slender member 12 is provided around the heating pipe 7 to disturb the flow of the combustion gas around the heating pipe and extend the surface of the pipe to improve the coefficient of heat transfer between the combustion gas and the working fluid in the heating pipe. The heating pipe 7 is shortened to reduce the drop of the pressure of the working fluid due to the friction on the wall of the heating pipe and diminish the unavailable volume of the engine to heighten the compression ratio of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Stirling engine having a compact heater, and particularly to improving the thermal efficiency of the heater tube.

The Stirling engine is said to have features such as higher thermal efficiency, lower operating noise, and cleaner exhaust than conventional gasoline engines, and research is progressing in various fields. -It is said to be nearing the stage of practical use as a prime mover for machine preparation.

FIG. 1 is a block diagram of a Stirling engine that has been studied in the past. In the figure, (1) is a cylinder chamber that houses, for example, a first piston (2) and a second piston (3). The cylinder chamber (
1) is divided into a high temperature section (4) and a low temperature section (5).

A regenerator (6) is placed outside this cylinder chamber (1),
(7) is a tenth flow path that communicates the high temperature part (4) of the cylinder chamber with the regenerator (6), and is, for example, a heater pipe. The plurality of heater tubes communicate with the high temperature section (4) through holes arranged radially in the wall of the high temperature section (4) of the cylinder chamber, and are configured, for example, in a U-shape. (8) is a second flow path that communicates the low temperature part (5) of the cylinder chamber with the regenerator (6), and the working fluid flowing through this path is cooled by a cooler (9). 00 is a burner that heats the working fluid flowing inside the heater pipe (7), and αυ is a mechanism unit that extracts the output of the engine to the outside.

In the Stirling engine configured as described above, the cylinder chamber is filled with working fluid, and when the first piston (2) descends, the working fluid flows into the low-temperature part (
5) to the second flow path (8), the regenerator (6), and the heater pipe (
7) and flows to the high temperature part (4) of the cylinder chamber.

At this time, the low-temperature working fluid is given heat by the regenerator (6) made of a heat storage material, and when it flows through the heater pipe (7), the combustion gas from the burner αQ flows in the direction of arrow A. This combustion gas is heated from the outside of the heater pipe (7) and becomes a high-temperature working fluid that enters the high-temperature section (4). As a result, the high temperature section (4) of the cylinder chamber is filled with a large amount of high temperature working fluid, and the expansion energy of this working fluid is transferred to the mechanism section α.
Take it out to the outside with υ.

In the above, the heater pipe (7) is a place where heat exchange is performed between the working fluid flowing inside and the combustion gas flowing outside.
The length and diameter of the heater tube (7) are determined by the amount of heat exchange and the amount of working fluid.

Since the conventional Stirling engine is configured as described above, it is difficult to downsize the heater tube, and the space that is not directly involved in working with the working fluid, that is, the heater tube (7), is difficult to downsize.
This makes it difficult to reduce the dead volume of the regenerator (6), the second flow path (8), etc., and this has the drawback that the compression ratio of the Stirling engine cannot be increased.

This invention was made in order to eliminate the above-mentioned drawbacks, and by equipping the Stirling engine with a spiral rod surrounding the outer surface of the heater tube, the heat transfer coefficient of the heater tube is increased, and the heat transfer coefficient of the heater tube is increased. As a result, the aim is to downsize the heater tube, reduce dead volume, and provide a Stirling engine with a high compression ratio.

An embodiment of the invention will be described with reference to the drawings. FIG. 2 is a side view showing a part of the Stirling engine, and FIG. 3 is an abbreviated view of FIG. 2 seen from above. In the figure, 02 is a spiral wire that surrounds the heater tube (7) and is soldered, for example.

In Fig. 2, the working fluid is connected to the regenerator (6), the heater pipe (
7) When flowing to the high temperature part (4) of the cylinder chamber, the combustion gas shown by arrow A exchanges heat with the working fluid in the heater tube (7). The spiral wire α is
To disturb the flow of combustion gas around the heater tube (7) and increase the surface area of the heater tube (7), the heat transfer coefficient between the working fluid in the heater tube (7) and the combustion gas is increased.

Therefore, the heater pipe (7) can be shortened, and it is possible to reduce pressure drop due to friction of the working fluid with the heater pipe wall and reduce dead volume. In this embodiment, the heater tube attached to the cylinder chamber is installed so that the interval is equal to the outer diameter of the spiral wire (2), so the outer diameter of the outer diameter of the spiral wire (2) is equal to the outer diameter of the heater tube ( 7), the wires 02 are brought into contact with each other, but the outer diameter of the wire 02 can be any value as long as it fits between the heater tubes (7). In addition, as shown in Figure 4, the winding pitch of the wire (A) is
If the wire diameter is twice the wire diameter in 2), the heat transfer area of this portion of the heater tube (7) will be approximately doubled, and a higher effect will be obtained.

As another example, as shown in FIG. 5, if the winding positions of the wires are shifted between adjacent heater tubes (7) so that the convex part of the adjacent wire α-gong is located in one of the four parts, Higher effects can be obtained. Also, connect the wire (
The winding pitch of 2) may be changed. Further, the material is not limited to a wire, but may be a plate-shaped metal rod or a disc-shaped metal rod.

Also, the place where the spiral rod is wound is the heater tube (7
) and the high temperature section (4), and may be partially or completely.

As explained above, the present invention provides a first flow path that communicates between the high temperature part of the cylinder chamber of the Stirling engine and a regenerator placed outside the cylinder chamber, by providing a spiral rod surrounding this flow path. This has the effect of increasing the heat transfer coefficient in the flow path, thereby reducing the dead volume, and obtaining a Stirling engine with a high compression ratio.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a conventional Stirling engine, FIG. 2 is a side view of the Stirling engine according to an embodiment of the present invention, and FIG.
The figure is a partial side view showing still another embodiment. In the figure, (1) is the cylinder chamber, (2) is the first piston, (3) is the second piston, (4) is the high temperature section, (5) is the
) is the low temperature section, (6) is the regenerator, (7) is the first flow path,
(8) is the second flow path, (9) is the cooler, α old burner, 0]) is the mechanical part, and (2) is the spiral rod. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent Makoto Kuzuno - Figure 1 Figure 2 Figure 3 Figure 4 Figure S

Claims (4)

[Claims] (1) A cylinder chamber composed of a high temperature section and a low temperature section, a regenerator placed outside the cylinder chamber, a first flow path communicating the high temperature section and the regenerator, and the low temperature section and the regenerator. a burner that heats the working fluid flowing through the first flow path; a cooler that cools the working fluid flowing within the second flow path; A mechanical part that extracts the expansion energy of the working flow to the outside,
A Stirling engine including a spiral rod surrounding an outer surface of the first flow path. (2) The Stirling engine according to claim 1, wherein the first flow passages installed in the cylinder chamber are installed at intervals equal to the outside diameter of the spiral rod. (3) The Stirling engine according to claim 1 or 2, characterized in that the rods are brazed to each other by shifting the winding positions of the rods in adjacent first flow paths. (4) The Stirling engine according to claim 1, 2, or 8, wherein the rods are brazed at different winding intervals in adjacent first flow paths.