JP2542614B2 - Stirling engine - Google Patents

Description

The present invention relates to a Stirling engine, and more particularly to a Stirling engine that performs output control by utilizing pressure fluctuation in a buffer tank that communicates with a space behind a piston. .

(Prior Art) In recent years, as part of energy saving, the Stirling engine has been reviewed and enthusiastic research has been conducted. There are various types of Stirling engines, for example L
Taking the example of a two-piston system called a type, a regenerative heat exchanger is connected in a closed flow path configuration between two power cylinders each containing a power piston, and one end of the regenerative heat exchanger The heater is used to heat the flow passage between the power cylinder and the power cylinder, and the cooler is used to cool the flow passage between the other end of the regenerative heat exchanger and the other power cylinder.

In addition, in this type of Stirling engine, when the piston reciprocates, the working gas in the space behind the piston becomes resistance, and the output and efficiency of the engine decrease, so
In order to reduce the pumping loss in the piston back space, a pipe hole is provided in the cylinder in the piston back space, and a buffer tank having a sufficient capacity is connected to this. In this case, when the working gas or air in the rear space of the piston receives a compressive force, it is released to the buffer tank through the pipe through the pipe hole provided in the cylinder in the rear space of the piston. On the contrary, when the dynamic gas or air receives the expansion force, the working gas or air is moved from the buffer tank to the space behind the piston. This reduces the fluctuation range of the compression of working gas and air in the space behind the piston.

On the other hand, in the Stirling engine, in order to control the output, it is necessary to control the pressure (filling pressure) of the working gas in the working space. That is, when the load of the Stirling engine is increased, the filling pressure of the working gas is increased to increase the output, and conversely, when the load is reduced, the filling pressure is decreased to decrease the output. A compression device for compressing the working gas from the working space or the tank and moving the working gas to the tank or the working space is used for controlling the filling pressure. However, since the compression device generally uses an electric motor as a power source, when it is incorporated in a Stirling engine, the size and weight of the engine are increased and a large installation space is required. In addition, such a compression device complicates assembly and maintenance.

(Problems to be Solved by the Invention) As described above, in the conventional Stirling engine,
In order to control the filling pressure of the working gas in the working space for output control, a compressor powered by an electric motor is required,
There has been a problem that the installation space increases due to the increase in size and weight of the engine, and the assembly and maintenance become complicated.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a Stirling engine that can realize a filling pressure control of a working gas in a working space with a simple configuration.

[Structure of the Invention] (Means for Solving Problems) According to the present invention, a buffer tank communicating with a piston back space of a Stirling engine is operated by pressure fluctuation in the buffer tank, and pressures in an operating space and a surge tank are It is characterized in that a compressor for sucking / compressing the working gas in one of the working space and the surge tank and moving it to the other is installed according to the relationship.

(Operation) When the filling pressure of the working gas in the working space is higher than the pressure of the working gas in the surge tank, the working gas in the working space is guided to the compression device, and after being compressed, moves to the surge tank. On the contrary, when the filling pressure of the working gas in the working space is lower than the pressure of the working gas in the surge tank, the working gas in the surge tank is guided to the compression device, is compressed, and then moves to the working space. As a result, output control is performed according to the load fluctuation. The pressures of the working gas and air in the buffer tank fluctuate as the piston reciprocates. In the present invention, the compression device operates by using the pressure fluctuation in the buffer tank as power. Therefore, it is possible to perform the charging pressure control of the working gas for the output control with a configuration that does not require a power source such as an electric motor and has a very simple and space-saving configuration.

(Example) Hereinafter, the Example of this invention is described.

FIG. 1 is a sectional view showing a schematic configuration of a Stirling engine according to an embodiment of the present invention. The Stirling engine body 1 is roughly divided into a power cylinder 2 (hereinafter referred to as an expansion cylinder) used for expanding a working gas, and a power piston 3 (hereinafter referred to as an expansion cylinder) slidably mounted in the expansion cylinder 2. An expansion piston), a power cylinder 4 used for compression of working gas (hereinafter referred to as a compression cylinder), and a power piston 5 slidably mounted in the compression cylinder 4 (hereinafter referred to as a compression piston). Refer to)
A heater 6, a regenerative heat exchanger 7 and a cooler 8 provided between the expansion cylinder 2 and the compression cylinder 4, cranks (also referred to as connecting rods) 9 and 10 to the expansion piston 3 and the compression piston 5, respectively. It is configured with an output shaft 13 connected via shafts 11 and 12.

The heater 6 has a combustion chamber 16 formed by partially arranging a heat insulating material 15 so as to surround the head 14 of the expansion cylinder 2, and a plurality of heat exchangers 17 arranged in the combustion chamber 16. Combustion chamber
It is composed of a fuel supply nozzle 18 arranged so as to face 16 and an air preheater 19 arranged so as to surround the combustion chamber 16 and preheat the air required for combustion with combustion exhaust gas.

Each of the heat exchangers 17 has one end of each gas passage communicating with the top of the expansion cylinder 2 and the other end communicating with a manifold 20 formed in the head 14, and is arranged in a funnel shape as a whole. There is. The manifold 20 is connected to a regenerative heat exchanger 7 via a connecting pipe 21, and the regenerative heat exchanger 7 is connected to a compression cylinder 4 via a cooler 8 constituted by the heat exchanger.
Is connected to the top of the. A space surrounded by the expansion cylinder 2 and the expansion piston 3, each heat exchanger 17, a manifold 20, a connecting pipe 21, a regenerative heat exchanger 7, a cooler 8, a compression cylinder 4 and a compression piston 5. A working gas such as He in the working space 24
It is filled with gas. The nozzle 18 is connected to a fuel supply source (not shown) via a fuel control valve (not shown), and the air inlet 22 of the air preheater 19 is connected to the discharge side of a blower (not shown).

In addition, a gathering space 30 is formed in a part of the crank chamber portion 25 that houses the cranks 9, 10 and the like. Expansion piston 3
A communication hole 33 is formed on the outer peripheral portion of the crosshead portion 31 for allowing the piston back space 32 and the collection space 30 to communicate with each other. The communication hole 33 is formed by cutting the outer peripheral portion of the crosshead portion 31 over the entire vertical length thereof. Further, the gathering space 30 is formed by a cross head portion 31 and a portion of the crank chamber portion 25 where the lower portion of the cylinder is formed by a manufacturing method such as cutting or casting. The gathering space 30 is connected to the buffer tank 50 via a pipe 34. Similarly, a collecting space 40 is provided for the compression piston 5 of the compression cylinder 4. The gathering space 40 is communicated with the piston back space 42 by a communication hole 43 formed by cutting the crosshead portion 41 of the compression piston 5, and is also connected with a buffer tank 50 via a pipe 44. And the meeting space
30, 40 are connected via a connection space 51 in the crank chamber portion 25. The connection space 51 is formed by manufacturing the crank chamber portion 25 by cutting or casting. If it is necessary to keep the pressure balance between the buffer tank 50 and the crank chamber 25, the connection pipe 52 may be used to connect the two.

On the other hand, the buffer tank 50 has a compression device 60 based on the present invention.
Is installed. This compressor 60 is a buffer tank
By operating by the pressure fluctuations of the air and the working gas in 50, either the working gas in the working space 24 or the surge tank 70 is sucked or sucked according to the pressure relationship in the working space 24 and the surge tank 70. It is compressed and moved to the other side, and its configuration is as follows.

That is, a flat conical space 62 communicating with the buffer tank 50 through the communication hole 61 is formed.
A compression valve is formed by providing the diaphragm 63 having a thickness of about 0 μm to 1 mm. The section 62 is on the side opposite to the inside of the buffer tank 50, and is a connection pipe as a working gas flow path leading to the working space 24 and the surge tank 70.
It communicates with 64,65. Check valves 66 and 67 are inserted in the middle of the connecting pipes 64 and 65, respectively, in the same direction as illustrated. The compression device 60 is constituted by these compression valves and the check valves 66, 67. Short circuit valve (hereinafter referred to as short circuit valve) on the compression valve side of the check valves 66, 67.
Both ends of 68 are connected, and both ends of a flow path opening / closing valve 69 are connected to the working space 24 and the surge tank 70 side. The short-circuit valve 68 is opened when the operation of the compressor 60 is stopped, and the flow path opening / closing valve 69 controls the filling pressure of the working gas in the working space 24 by the operation of the compressor 60. It is open to people.

Next, the operation of the Stirling engine configured as above will be described. First, send the fuel from the nozzle 18,
Ignite this. In addition, the output shaft 13
Temporarily rotate. Since the output shaft 13 is rotated by the external power source, the expansion piston 3 and the compression piston 5 connected to the output shaft 13 via the crankshafts 11, 12, and cranks 9, 10 have a certain phase difference. Move back and forth. When the expansion piston 3 shifts to the compression process by this reciprocating motion,
Most of the working gas in the expansion cylinder 2 flows into the compression cylinder 4 through the heat exchanger 7 and the cooler 8 at the time when the expansion piston 3 reaches the top dead center.
Pour into. At this time, the heat of the working gas is accumulated in the regenerative heat exchanger 7 while passing through the regenerative heat exchanger 7, and is further cooled while passing through the cooler 8. When the compression piston 5 starts to move from the bottom dead center to the top dead center with the rotation of the output shaft 13, the low temperature working gas in the compression cylinder 4 is compressed, and the expansion cylinder is expanded in a path opposite to the conventional path. Pour into 2. At this time, the working gas absorbs heat while passing through the regeneration heat exchanger 7 and is heated to a high temperature,
It is then further heated as it passes through each heat exchanger 17. The high-temperature working gas flowing into the expansion cylinder 2 expands and pushes down the expansion piston 3. After that, the above-described operation is repeated, and the output shaft 13 continues to rotate even when the external power source is turned off, and the Stirling engine is operated.

The reciprocating motion of the expansion piston 3 causes a pressure fluctuation of the working gas in the piston back space 32. For example, when the piston 3 descends, the working gas in the piston back space 32 is compressed. At this time, the piston rear space 32 has a connecting hole 33.
Since it is connected to the gathering space 30 via, the pressure fluctuation width due to the compression is once reduced by the gathering space 30,
Thereafter, the compressed working gas will escape to the buffer tank 50 through the pipe 34. In addition, the expansion piston 3
When the pressure rises, the working gas in the piston back space 32 is expanded. The pressure fluctuation width due to this expansion is also temporarily reduced by the action of the gathering space 30 as in the above. Then, the working gas is supplied from the buffer tank 50 through the pipe 34. In this way, the pressure fluctuation width of the working gas in the piston back space 32 due to the reciprocating motion of the expansion piston 3 is temporarily reduced by the gathering space 30 and then released to the buffer tank 50, whereby the pressure fluctuation in the piston back space 32 is compensated. ,
Also, the piston rear space 42 due to the reciprocating motion of the compression piston 5
Similarly, the pressure fluctuation of the collecting space 40 and the buffer tank 50
Will be compensated by.

Here, when the pressure fluctuation in the buffer tank 50 occurs,
The compression device 60 operates with this power. That is, when the pressure in the buffer tank 50 decreases, the diaphragm 63
Shifts to the right side in the figure. In this case, for example, when the filling pressure of the working gas becomes higher than the pressure of the working gas in the surge tank 70 due to the pressure fluctuation of the working gas in the working space 24, the working gas in the working space 24 becomes the connecting pipe 64. And via check valve 66 into the compression valve space 62. When the pressure in the buffer tank 50 next rises and the diaphragm 63 shifts to the left side in the drawing, the working gas that has entered this space 62 is pushed toward the connecting pipe 65 side by the diaphragm 63 and compressed, and the non-return Transfer to surge tank 70 via valve 67.

On the contrary, when the filling pressure of the working gas becomes lower than the pressure of the working gas in the surge tank 70 due to the pressure fluctuation of the working gas in the working space 24, the working gas in the surge tank 70 flows. It is guided to the compression device 60 including the check valves 66 and 67 and the compression valve via the passage opening / closing valve 69, and after being similarly compressed, moves to the operation section 24 again via the passage opening / closing valve 69. .

In this way, by controlling the filling pressure of the working gas in the working space 24 by the compression device 60, the output control of the Stirling engine according to the fluctuation of the load is performed.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be carried out without departing from the scope of the invention. For example, the embodiment is an example in which the present invention is applied to the two-piston type, but the present invention can also be applied to the displacer type.

Further, as the compression device 60 utilizing the pressure fluctuation in the buffer tank 50, the system using the diaphragm 63 is illustrated, but a system using a piston, for example, can also be adopted.

Further, although the compressor 60 is used for controlling the filling pressure of the working gas in the working space 24 in the embodiment, it is also possible to perform the output control by controlling the supply of the combustion air in the combustion chamber 16. In that case, for example, the connection pipe 64 to the working space 24 in the figure is connected to the air introduction port 22 or the like of the air preheater 16,
The surge tank 70 may be filled with air.

EFFECTS OF THE INVENTION According to the present invention, the buffer tank communicating with the piston back space of the Stirling engine is operated by the pressure fluctuation in the buffer tank as a power source, so that the pressure relationship in the working space and the surge tank can be changed. By installing a compressor that sucks and compresses the working gas between the working space and the surge tank to perform output control according to load fluctuations, a power source such as an electric motor can be used like a conventional compressor. The Stirling engine can be made smaller and lighter without the need. Moreover, since there is no accessory such as an electric motor, the engine can be easily assembled and maintained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a Stirling engine according to an embodiment of the present invention. 1 ... Stirling engine body, 2 ... expansion cylinder, 3 ... expansion piston, ... compression cylinder, 5 ... compression piston, 6 ... heater, 7 ... regenerative heat exchanger, 8 ...
… Cooler, 16 …… combustion chamber, 17 …… heat exchanger, 18 …… nozzle, 19 …… air preheater, 30,40 …… collecting space, 31,41 ……
Cross head part, 32,42 …… Piston back space, 33,43…
… Communication hole, 34,44,53 …… pipe, 50 …… buffer tank, 51 …… connection space, 60 …… compressor, 61 …… communication hole,
62 …… space, 63 …… diaphragm, 64,64 …… connection pipe (working gas passage), 66,67 …… check valve, 68 …… short-circuit valve, 69 …… passage valve, 70 …… Surge tank.

Claims (2)

(57) [Claims] 1. A Stirling engine main body having a working space filled with a working fluid and closed by a piston, and a Stirling engine main body provided outside the Stirling engine main body and communicating with a rear space of the piston of the Stirling engine main body. In a Stirling engine including a buffer tank, the buffer tank is operated by a pressure fluctuation in the buffer tank, and either one of the working space and the surge tank is operated according to the pressure relationship between the working space and the surge tank. The Stirling engine is equipped with a compression device that sucks and compresses the working gas of and moves it to the other side. 2. A compression device, which includes a diaphragm that operates due to pressure fluctuations in a buffer tank, both ends of which are connected to a working space and a surge tank via a working gas flow path, and the compression valve. A first gas cylinder inserted into the working gas flow path between the working space and the surge tank in the same direction, and connected at one end to the working space side and to the surge tank side directly or via a flow path opening / closing valve.
The Stirling engine according to claim 1, further comprising: and a second check valve.