JP2000249416A - Gas compression expansion machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a differential pressure in the average pressure of a working space and a buffer space. SOLUTION: In a gas compression expansion machine 10 which compresses or expands a working gas of a working space 53 by the reciprocation of a piston 51, a cylindrical piston ring 59 is fitted into the piston 51 so as to enclose the circumferential surface of the piston facing a sliding surface of a cylinder 52 and filter members 60 are arranged respectively on the top surface and on the undersurface of the piston facing the working space 53 and the buffer space 56.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas compression / expansion machine such as a Stirling engine for generating power and a Stirling refrigerator for generating low temperature.

[0002]

2. Description of the Related Art In recent years, there has been an urgent need to develop techniques for preserving various samples and various materials at extremely low temperatures in advanced technology fields such as the field of biotechnology and the field of electronic devices. In particular, gas compression / expansion machines such as Stirling refrigerators are attracting attention as means for achieving the extremely low temperature, and are going to be widely used for cooling, biomedical freezers, freezers, etc. for various infrared sensors, superconducting devices, and the like.

FIG. 3 shows a schematic configuration of such a gas compression / expansion machine. The gas compression / expansion machine 100 includes a compression unit 150 which is a piston-type compressor having a compression piston 151,
It has an expansion section 130 provided with a displacer 131, a drive section 120 provided with a crank mechanism 121, and the like.
0 and the expansion section 130 are communicated with each other through a gas flow path 170.

[0004] The compression section 150 is provided with a compression piston 15.
1 for accommodating 1 and compression cylinder 152
Compression space 1 provided on the head side (left side in FIG. 3)
53, radiating fins 154 provided on the outer surface of the compression cylinder 152 to radiate the heat of the working gas generated by the compression to the outside, an oil seal portion 155 provided on the drive portion 120 side of the compression cylinder 152, and a compression piston 151 Space 15 formed by the compression cylinder 152
6. Insert the oil seal 155 into the compression piston 15
1 has a compression piston 151 and the like for transmitting a driving force.

The expansion section 130 includes an expansion cylinder 132 for accommodating the displacer 131 and an expansion space 13 provided on the head side (upper side in FIG. 3) of the expansion cylinder 132.
4, the cold storage material 133 provided in the displacer 131
The cold head 112 is attached to the head of the expansion cylinder 132.

[0006] The drive unit 120 is provided in the crank chamber 122.
A connecting rod 123 connected to the crank mechanism 121, the crank mechanism 121 and the compression piston rod 157, and a connecting rod 124 connected to the crank mechanism 121 and the displacer rod 135.
The bottom of the crank chamber 122 stores oil for lubricating the crank mechanism 121 and the like.

In such a configuration, when the crank mechanism 121 rotates, the rotating power is reduced by the connecting rod 1.
It is transmitted to the compression piston 151 and the displacer 131 via 23, 124 and the like.

At this time, the two connecting rods 1
23 and 124 receive the driving force from the crank mechanism 121 at the same point of action, so that the compression piston 151 reciprocates with a phase shift of about 90 degrees from the displacer 131.

When the compression piston 151 moves from the right end (bottom dead center) in FIG. 3 to the left end (top dead center), the working gas in the compression space 153 is isothermally compressed.

During this time, the displacer 131 moves upward,
After reaching the top dead center, it starts to move down. The working gas compressed by the upward movement of the compression piston 151 is supplied to the gas passage 1
When the displacer 131 is moved downward through the expansion unit 130 via the 70, the working gas passes through the cold storage material 133, exchanges heat with the cold storage material 133, and is sent to the expansion space 134.

As the displacer 131 reaches the bottom dead center, the compression piston 151 moves from the top dead center to the bottom dead center, and the working gas expands and cools down. Since the expansion process at this time is an isothermal expansion process, external heat is absorbed as much as the temperature is reduced by the expansion. As a result, the cold head 112 provided on the head of the expansion cylinder 132 is cooled.

Then, as the compression piston 151 approaches the bottom dead center, the displacer 131 starts moving upward, the working gas passes through the displacer 131, absorbs heat from the cold storage material 133, and one cycle is completed.

In the gas compression / expansion device having the above structure, a ring groove is formed in the compression piston 151, and a piston ring 159 is fitted in the ring groove. When the piston ring 129 comes into close contact with the ring groove and the compression cylinder 152, the compression piston 1
The close contact between the compression cylinder 51 and the compression cylinder 152 is maintained.

[0014]

However, when the piston compressor according to the above configuration is used, a differential pressure is generated between the average pressure in the compression space 153 and the average pressure in the buffer space 156, and the differential pressure is generated. Is applied to the compression piston 151, and as a result, the driving unit 1
There is a problem that the power consumption of the device 20 increases and the efficiency of the device decreases.

FIGS. 4 to 6 show the mechanism of generating such a differential pressure.
This will be described with reference to FIG. Incidentally, the mechanism of the differential pressure generation has not been clarified scientifically at present, and the mechanism described later is considered to be one model thereof.

FIG. 4 is a diagram showing pressure fluctuation when the average pressure in the compression space 153 increases. In the figure,
The solid line shows the pressure fluctuation in the compression space 153, and the dotted line shows the pressure fluctuation in the buffer space 156. FIGS. 5 and 6 are diagrams schematically showing the movement of the piston ring 159 accompanying the reciprocating motion of the compression piston 151. FIGS. 5A and 6A show that the compression piston 151 has the compression space 153. 5 (b) and FIG. 6 (b) show a case where the camera has moved to the buffer space 156 side.

If the piston ring 159 is functioning normally, the working gas in the compression space 153 and the buffer space 156 should not move relative to each other, and no differential pressure of the average pressure should occur. However, in reality, a difference occurs in the average pressure between the compression space 153 and the buffer space 156 as illustrated in FIG.

The piston ring 159 is provided for the compression piston 1
51 is inserted into a ring groove 160 formed along the peripheral surface (see FIGS. 5 and 6). At this time, the ring groove 16
0 and upper and lower side surfaces 160a, 160c and piston ring 15
At least one opposing side surface of the upper and lower side surfaces 159a, 159c of 9 is not closely contacted, and gaps Ga, Gc are formed. Also, the bottom 160b of the ring groove 160 and the bottom 159b of the piston ring 159 are not in close contact,
A gap Gb is formed.

The gaps Ga to Gc are formed in the ring groove 1.
This is because the piston ring 159 is inserted and assembled after the formation of the piston 60, so that it is difficult to bring the piston ring 159 into close contact.

That is, it is necessary for the compression piston 151 to be in close contact with the compression cylinder 152 in order to perform the compression with high efficiency. However, since there are processing errors of the compression piston 151 and differences in thermal expansion, etc. Cannot always be satisfied, and gaps G1 and G2 are generated.

A piston ring 159 is used to close the gaps G1 and G2. However, the piston ring 159 also has processing errors, thermal expansion, and the like. Further, since the piston ring 159 is inserted and fitted after the ring groove 160 is formed as described above, the adhesion between the piston ring 159 and the compression cylinder 152 is increased. It is not easy to secure.

Therefore, gaps Ga to Gc are formed so that the working gas in the compression space 153 or the buffer space 156 enters the gap Gb through the gaps Ga and Gc.

The intruded working gas urges the bottom surface 159b of the piston ring 159 toward the compression cylinder 152 (solid arrows in FIGS. 5 and 6), whereby the piston ring 159 and the compression cylinder 152 are always in close contact with each other. Like that.

The piston ring 159 and the ring groove 1
Since the upper and lower side surfaces of the piston ring 159 are not always in close contact with each other, the piston ring 159 moves in the ring groove 160 with the movement of the compression piston 151.

However, the piston ring 159 is urged in the space direction on the low pressure side by the pressure of the higher pressure space of the compression space 153 or the buffer space 156 (dotted arrows in FIGS. 5 and 6). The upper or lower side 160a, 160c of the ring groove 160 and the piston ring 159
The upper and lower side surfaces 160a, 160c are kept in close contact with each other, and the movement of the working gas between the compression space 153 and the buffer space 156 is restricted.

However, with the movement of the compression piston 151, various foreign substances (for example, powder of the piston ring 159 which has been worn by sliding with the compression cylinder 152) are deposited on the upper side 160a or the lower side 160c of the ring groove 160. The piston ring 159 and the ring groove 16
0 may not be in close contact.

Then, the upper side 160a or the lower side 160
If a foreign substance adheres to any one of c, the above-described differential pressure will occur due to a phenomenon described later.

FIG. 6 shows the movement of the piston ring 159 accompanying the movement of the compression piston 151 when the foreign matter B adheres to the upper side surface 160a of the ring groove 160.

In this case, when the compression piston 151 moves toward the compression space 153 (see FIG. 6A), the compression space 153 is reduced and the buffer space 156 is expanded.
Is higher than the pressure in the buffer space 156.

As a result, the piston ring 159 moves toward the lower surface 160c of the seal groove 160 to which the foreign matter B does not adhere, and the lower surface 159c of the piston ring 159 and the lower surface 160c of the seal groove 160 come into close contact. Therefore, the working gas does not move from the compression space 153 to the buffer space 156.

On the other hand, when the compression piston 151 moves toward the buffer space 156 (see FIG. 6B), the compression space 153 expands, the buffer space 156 contracts, and the compression space 153 expands.
Is smaller than the pressure in the buffer space 156.

At this time, the piston ring 159 moves toward the upper surface 160a of the seal groove 160 to which the foreign matter B is attached.
a, and the working gas moves from the buffer space 156 to the compression space 153 side (two-point arrow in FIG. 6B).

Therefore, the average pressure in the compression space 153 is higher than the average pressure in the buffer space 156, and a differential pressure as shown in FIG. 4 is generated.

Although the case where the foreign matter B adheres to the upper side surface 160a of the seal groove 160 has been described here, the same applies to the lower side surface 160c, and any one of the upper and lower side surfaces 159a and 159c of the piston ring 159. It is presumed that the same phenomenon occurs even if it adheres to the surface. However, when the foreign matter B adheres to the lower side surface 160c of the seal groove 160, the average pressure of the compression space 153 increases.
6 below the average pressure.

The present invention has been made in view of the above points, and has as its object to provide a gas compression / expansion machine in which the generation of the above-mentioned differential pressure is suppressed.

[0036]

According to the present invention, a working space and a buffer space are formed with a piston disposed in a cylinder interposed therebetween, and the working gas in the working space is compressed by reciprocating the piston. Or, in a gas compression expander formed by expansion, a cylindrical piston ring fitted to the piston and a piston ring fitted to the piston so as to surround a piston peripheral surface facing the sliding surface of the cylinder, and the working space and the buffer space. And a filter member disposed on the upper and lower surfaces of the piston facing each other.

By using this configuration, foreign matter generated due to the reciprocating motion of the piston is removed by the filter member, and no foreign matter adheres between the peripheral surface of the piston and the piston ring. Can be prevented from occurring.

Further, a driving unit and a compression piston receiving driving force from the driving unit are reciprocally disposed in the compression cylinder, and a compression space and a buffer space are sandwiched between the compression piston and the compression space in the compression cylinder. A compression section formed to compress the working gas in the compression space; and a displacer reciprocating in the expansion cylinder by receiving a driving force out of phase with the compression section, thereby expanding the working gas from the compression section. And a cylindrical piston ring fitted to the compression piston so as to surround a peripheral surface of the compression piston facing a sliding surface of the compression cylinder. And a filter member disposed on the upper surface and the lower surface of the piston facing the space and the buffer space.

By using this configuration, in a one-piston, one-displacer type gas compression / expansion machine, it is possible to prevent a differential pressure from occurring in the average pressure between the compression space and the buffer space, thereby improving the coefficient of performance. Can be.

The compression section and the expansion section may be arranged side by side and fixed to the drive section. By using this configuration, the compression section and the expansion section can be arranged in the same direction, and the area occupied by the entire apparatus can be reduced.

[0041]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing a configuration of a Stirling refrigerator as an embodiment to which a gas compression / expansion machine of the present invention is applied. The Stirling refrigerator 10 includes a compression section 50 which is a piston type compressor having a compression piston 51, an expansion section 30 having a displacer 31, a crank chamber 20 as a drive section having a crank mechanism 21, and the like. Expansion part 30 and compression part 5
0 are provided in the upper part of the crankcase 20 in parallel.

The crank chamber 20 includes a rotor 25 for applying a rotational driving force to the crank mechanism 21 and cranks 21a,
1b, connecting rods 23, 24 connected to
It has cross guides 26 and 27 connected to connecting rods 23 and 24, and has a crank mechanism 21 at the bottom thereof.
Oil for lubricating is stored.

The cranks 21a and 21b are connected eccentrically to the shaft 21c, and the mounting angles of the cranks 21a and 21b are set so that the phase of the compression piston 51 is delayed by about 90 degrees with respect to the phase of the displacer 31. Is set.

The expansion section 30 includes an expansion cylinder 32 for accommodating the displacer 31, an expansion space 34 provided on the head side (upper side in FIG. 1) of the expansion cylinder 32, and an expansion cylinder 34 on the crank chamber 20 side of the expansion cylinder 32. An oil seal portion 36 disposed therein; a displacer rod 35 for transmitting a driving force to the displacer 31 through the oil seal portion 36; and a cold storage material 33 provided in the displacer 31.
The cold head 12 for taking out cold energy is attached to the head of the expansion cylinder 32.

The compression section 50 includes a compression cylinder 52 for accommodating a compression piston 51 and a compression space 53 provided on the head side (upper side in FIG. 1) of the compression cylinder 52.
A compression housing portion 54 which is provided over the outer surface of the compression cylinder 52, and on which a radiating fin for radiating the heat of the working gas generated by the compression to the outside is attached.
And an oil seal portion 55 disposed on the crank chamber 20 side of the compression cylinder 52, a compression piston rod 57 for transmitting a driving force to the compression piston 51 through the oil seal portion 55, and the like. The compression housing portion 54 is provided so as to cover the compression cylinder 52, and forms a gas flow passage 70 that communicates the compression portion 50 and the expansion portion 30 with the outer wall surface of the compression cylinder 52. A radiation fin 54a is attached around the outer wall of the housing 54.

The compression section 50 and the expansion section 30 are fixed to the crank chamber 20 side by side. This allows
By arranging them in the same direction, the occupied area of the entire apparatus can be reduced.

As shown in FIG. 2, a ring groove 51a is formed on the peripheral surface of the compression piston 51, and a cylindrical piston ring 59 is fitted into the ring groove 51a to surround the piston peripheral surface. And is in sliding contact with the compression cylinder 52. A filter for trapping foreign matter generated by the reciprocating motion of the compression piston 51 is provided on the upper and lower surfaces of the piston facing the compression space 53 and the buffer space 56 formed on the opposite side with the compression piston 51 interposed therebetween. A member 60 is provided. In this embodiment, the piston ring 59 is made of PTFE, and the filter member 60 is made of stainless steel of about 100 μm.
A stack of about 20 mesh members having a gap of m is used.

As a result, foreign matter generated due to the reciprocating motion of the compression piston 51 is removed by the filter member 60, so that no foreign matter adheres between the piston peripheral surface and the piston ring 59, and the compression space 53 and the buffer space Thus, it is possible to prevent the occurrence of a pressure difference between the average pressure and the average pressure.

Here, the buffer space 56 becomes a sealed space by the compression piston 51 and the oil seal portion 55, and acts as a resistance when the compression piston 51 is reciprocated. Is set larger than the compression space 53. However, if the volume of the buffer space 56 cannot be sufficiently ensured to reduce the size of the device, a buffer chamber (not shown) communicating with the buffer space is provided to increase the volume of the buffer space 56 effectively. May be.

In the description of this embodiment, the compression space 5
Although the case where the compression space 3 is formed on the head side of the compression cylinder 52 has been described, the invention is not limited to this.
The arrangement positions of 3 and the buffer space 56 may be reversed.

Next, the operation of the Stirling refrigerator 10 based on the above configuration will be described. When the crank mechanism 21 rotates, the rotating power is increased by the connecting rods 23 and 24.
The compression piston 51 is transmitted to the displacer 31 and the compression piston 51 via the like, and reciprocates with a phase delayed by about 90 degrees with respect to the displacer 31.

When the compression piston 51 moves from the bottom dead center to the top dead center, the working gas in the compression space 53 is compressed. During this time, the displacer 31 moves upward and reaches the top dead center, and then moves downward.

The working gas compressed with the upward movement of the compression piston 51 moves through the gas flow path 70 and radiates the fins 54a.
Then, the heat is dissipated and sent to the expansion section 30 side. When the displacer 31 moves down, the working gas passes through the cold storage material 33, exchanges heat with the cold storage material 33, and is sent to the expansion space 34.

As the displacer 31 reaches the bottom dead center, the compression piston 51 moves from the top dead center to the bottom dead center, and the working gas expands and cools down. Since the expansion process at this time is an isothermal expansion process, external heat is absorbed as much as the temperature is reduced by the expansion. That is, heat can be taken from the cold head 12.

As the compression piston 51 approaches the bottom dead center, the displacer 31 starts to move upward, the working gas passes through the displacer 31, exchanges heat with the cold storage material 33, and returns to the compression space 53 to complete one cycle.

In such a cycle, in order to increase the efficiency of the apparatus, it is necessary to quickly and efficiently radiate the heat of the working gas compressed by the compression section 50 to the outside. Therefore, in the present invention, a gap is formed between the compression housing portion 54 provided with the radiation fins 54a and the compression cylinder 52, and the gap serves as a gas flow path, so that the heat between the working gas and the radiation fins 54a is formed. The contact area is increased so that the heat of the working gas can be efficiently transmitted to the radiation fins 54a. Further, since the radiation fins 54a of the compression housing 64 are provided close to and around the gas flow path 70, the heat received from the working gas can be efficiently released to the outside air. Will be possible. Therefore, in the case of a refrigerator, the coefficient of performance can be increased.

Further, during the above-described cycle, if foreign matter adheres between the piston ring 59 and the ring groove 51a, the buffer space 56 and the compression space 53 are formed for the reason described above.
A differential pressure is generated in the average pressure between the piston ring and the piston ring 59. However, even if foreign matter is generated, the foreign matter is captured by the filter member 60. As a result, it is possible to prevent the generation of a differential pressure between the average pressures of the buffer space 56 and the compression space 53.

The description of the above embodiments is for the purpose of illustrating the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof.
Further, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

For example, in the description of the above embodiment, the case of the one-piston one-displacer type Stirling refrigerator 10 has been described. However, the present invention is not limited to this. It is also applicable to a Stirling refrigerator, in which case the above-described piston ring 59 is attached to the expansion piston.
Alternatively, a configuration in which the filter member 60 is provided may be employed.

[0060]

As described above, according to the present invention, it is possible to prevent a differential pressure from occurring in the average pressure between the working space and the buffer space, and it is possible to improve the efficiency of the apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a Stirling refrigerator according to one embodiment of the present invention.

FIG. 2 is a sectional view of a main part for explaining a peripheral configuration of a compression piston 51 of the apparatus in FIG. 1;

FIG. 3 is a schematic sectional view of a conventional Stirling refrigerator.

FIG. 4 is an explanatory diagram showing a state when a differential pressure is generated.

FIG. 5 is a diagram showing the movement of a piston ring when there is no foreign matter;

FIG. 6 is a view showing a movement of a piston ring when foreign matter is attached.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Stirling refrigerator (gas compression expander) 12 Cold head 20 Crank chamber (drive part) 21 Crank mechanism 30 Expansion part 31 Displacer 32 Expansion cylinder 33 Cold storage material 34 Expansion space 35 Displacer rod 50 Compression part 51 Compression piston 51a Ring groove 52 Compression cylinder 53 Compression space (operating space) 54 Compression housing (housing) 54a Radiator fin 55 Oil seal 56 Buffer space 57 Compression piston rod 59 Piston ring 60 Filter member 70 Communication passage

Claims (3)

[Claims] An operating space and a buffer space are formed with a piston disposed in a cylinder interposed therebetween, and a gas compression / expansion is achieved by compressing or expanding the working gas in the operating space by reciprocating the piston. A cylindrical piston ring fitted to the piston so as to surround a peripheral surface of the piston facing the sliding surface of the cylinder, and upper and lower surfaces of the piston facing the working space and the buffer space. And a filter member provided. 2. A driving unit and a compression piston receiving driving force from the driving unit are reciprocally disposed in a compression cylinder, and a compression space and a buffer space are sandwiched between the compression piston and the compression space in the compression cylinder. A compression section formed to compress the working gas in the compression space; and a displacer reciprocating in the expansion cylinder by receiving a driving force out of phase with the compression section, thereby expanding the working gas from the compression section. A compression piston having a cylindrical shape fitted to the compression piston so as to surround a peripheral surface of the compression piston facing a sliding surface of the compression cylinder; A filter member disposed on an upper surface and a lower surface of the piston facing the space and the buffer space. 3. The gas compression / expansion machine according to claim 2, wherein the compression section and the expansion section are arranged side by side and fixed to the drive section.