JP3566754B2 - Piston type pulse tube refrigerator using liquid lubricant - Google Patents

Description

[0001]
[Industrial applications]
The present invention can provide gas such as helium, hydrogen, and air by adiabatic expansion using a gas pressure source, so that it can be used for demands in temperature regions such as refrigeration, freezing, and cooling, and uses a liquid lubricant as a mechanical gas pressure source. The present invention relates to a gas refrigerator using a mechanical piston used and having a simple structure similar to a conventional orifice type pulse tube refrigerator and having an automatic removal function of the liquid lubricant mixed in refrigerant gas. .
[0002]
[Prior art]
As is known, the pulse tube refrigerator is configured to replace the piston in a conventional Stirling refrigerator with gas, and attention has been paid to the recent improvements in refrigeration efficiency and the reduction in the minimum temperature reached. They are starting to collect. Here, the above-mentioned Stirling refrigerator has a configuration as illustrated in FIG. 2 (A), and a compression piston B is operated by a motor drive unit A, thereby compressing the room temperature space C to thereby improve the entirety. The pressure increases, and the heat generated at this time is released to the outside by the cooling of the room temperature space C (compression process).
[0003]
Further, the expansion piston D increases the cooling space F while performing work to the external work recovery unit E, thereby lowering the overall pressure, thereby lowering the temperature of the low-temperature space F (expansion process). Then, the expansion piston D expels the cooling gas in the low-temperature space F through the regenerative heat exchanger G (wire mesh, metal particles, etc.) to the room temperature space C side, and at the same time, the compression piston B also moves. As it is, no heat is generated, and the generated cold heat is stored in the regenerative heat exchanger G and used for cooling the gas in the next process (moving process).
[0004]
In contrast to this Stirling refrigerator, as pulse tube refrigerators, a piston type pulse tube refrigerator (FIG. 2 (B)), a valve type pulse tube refrigerator (FIG. 2 (C)), and an orifice type pulse tube refrigerator (FIG. 3 (A)) is known. In the piston type pulse tube refrigerator, most of the expansion piston D in the Stirling refrigerator is replaced with a gas piston H. since H is stretchable in response to the pressure, but more efficient than the Stirling refrigerator decreases, the expansion piston D ₁ is lighter than from D, it eliminates the portion operating at low temperatures, it is possible high-speed operation .
[0005]
Next, the above-mentioned valve pulse tube refrigerator, a motor drive unit A and the compression piston B of the Stirling refrigerator, the expansion piston D work and recovery unit E, respectively the high pressure gas inflow side valve J ₁ and the low-pressure gas I ₁ and the outflow side valve J ₂ of I _2, by thus replaced with an inflow side valve L ₂ of the outlet-side valve L ₁ and the high-pressure gas K ₂ of the low-pressure gas K _1, which was made possible eliminates all moving parts However, there is a defect that the efficiency is reduced because the work is not recovered by the expansion piston D as in the Stirling refrigerator.
[0006]
Also, the orifice pulse tube refrigerator, a 3 outflow side valve L ₁ and the inflow side valve L ₂ as the in pulse tube M side (A), it was replaced with the orifice valve N and the buffer tank O Although the overall device is simplified, improvement in efficiency cannot be expected. Here, P is a compressor, Q ₁ and Q ₂ are a high pressure side pressure vessel and a low pressure side pressure vessel, respectively, R ₁ and R ₂ are heat exchangers using cooling water, S is a low temperature part, and T is It is a low-temperature side heat exchanger.
[0007]
Conventional example shown in FIG. 3 (B) to further the 3. In the drawing an orifice pulse tube refrigerator (A), the compressor P as a refrigerant gas pumping source, pressure vessel Q of the high-pressure side and low pressure side _1, Q _2, valve J ₁ on the inflow side and the outflow _side, J ₂ instead, such as using a mechanical high-pressure gas source U by mechanical compressor Toka expander, etc., and to improve the refrigeration efficiency Things.
[0008]
Additional mechanical high pressure gas source U is reciprocates the piston U ₂ of fitted into the cylinder U _1, this time, without using a liquid lubricant with respect to the piston U _2, the sealing material as a solid lubricant and to use a U _3. This is because, in this type of refrigerator, it is supposed that the refrigerant gas used should not contain a liquid lubricant such as oil or the like. high pressure source in the outlet side of the U, and Kakarihama or so as to attaching a special device for removing the oil component, the seal member U ₃ as described above to the piston U _2, cylinder U ₁ and the piston trying to ensure a sealed state between the U _2.
[0009]
[Problems to be solved by the invention]
The pulse tube refrigerator configured as described above has various advantages, and in particular, in the piston type orifice pulse tube refrigerator, the advantages can be utilized, and the improvement of the refrigerating efficiency can be achieved. although help, in the case of using the sealing member U ₃ by the solid lubricant is difficult to ensure the integrity of the sealing effect, and, of course will be poor in durability, yet oil lubrication commonly used Since a CFC freezing compressor or the like cannot be used, it becomes expensive.
[0010]
Of course, if a piston type using an inexpensive liquid lubricant is adopted, an apparatus for removing oil components in the refrigerant gas must be provided as described above, which not only makes the entire apparatus expensive, Reuse of the recovered oil component also requires extra labor. Since a liquid lubricant such as oil is used, it is needless to say that the lubricant is used in a temperature range where it does not solidify.
[0011]
The present invention has been studied in view of the difficulties in the above prior art, first, as in the prior art, before pressurizing the refrigerant gas into the regenerator, and closely examine the reason for trying to remove the oil component. However, since an extremely low temperature is to be generated by a pulse tube refrigerator, the device for removing the oil component is indispensable to avoid the oil component from being frozen in the regenerator or the pulse tube. is there.
[0012]
Therefore, in the present invention, a pulse tube refrigerator having a temperature range in which the liquid lubricant does not freeze is a major premise, and the oil component contained in the refrigerant gas is directly transferred to the regenerator, the pulse tube, and the buffer tank. It is sent. As a result, the liquid lubricating material adheres to the entire surface of the regenerative heat exchanger in which a large number of thin tubes provided in the regenerator are bundled or a large number of metal nets are arranged in layers. The first object is to utilize the material as a regenerative material, thereby improving the refrigeration efficiency, and enabling direct use of a piston-type compressor or the like using an inexpensive liquid lubricant. .
[0013]
The present invention in further, the liquid lubricant contained in the refrigerant gas is pumped as described above in gravity and pressure differential, yet the regenerator, the pulse tube, by using a check valve with a pipe from the buffer tank or the like piston refluxed to the side, it is to try to allow automatic re-use of the liquid lubricant This ensures that the second object.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a refrigerant gas pump having a piston space formed between a piston that operates through a liquid lubricant in a cylinder and a piston space between an upper end of the cylinder and the piston. The lower end of the regenerator provided with the regenerative heat exchanger installed above it is connected to the lower end of the regenerator by a refrigerant gas distribution pipe, and the upper end of the regenerator and the upper end of the pulse tube are connected by the low temperature part. At the same time, the lower end of the pulse tube at room temperature is connected to the buffer tank through an orifice valve, and the lower end of the regenerator, the lower end of the pulse tube, the lower end of the buffer tank, all or In part, there is provided a liquid lubricant recirculation pipe with a check valve that drops the collected liquid lubricant from the upper end of the cylinder of the refrigerant gas pump into the piston space. Liquid It is intended to provide a piston type pulse tube refrigerator with lubricant.
[0015]
[Action]
In the present invention, when the refrigerant gas pump is operated, the refrigerant gas is pressure-fed into the regenerator by the reciprocating motion of the piston. At this time, the liquid lubricant applied between the cylinder and the piston is Then, the refrigerant flows and adheres to the regenerative heat exchanger of the regenerator together with the refrigerant gas.
Therefore, the regenerative heat exchanger and the liquid lubricant adhering thereto act as a cold storage material, which promotes the refrigeration efficiency of the pulse tube refrigerator.
[0016]
In addition, the liquid lubricant in the regenerator flows down through the regenerative heat exchanger and the like, and flows down from the lower end of the regenerator to the above-described cylinder by the liquid lubricant recirculation pipe via a check valve, so that The liquid lubricant is reused without effort. At this time, if the liquid lubricant is allowed to flow down into the cylinder from the lower end of the pulse tube or the buffer tank as well as from the lower end of the pulse tube as well as the regenerator, the liquid lubricant can be further recovered. Rate can be improved.
[0017]
【Example】
The present invention will be described in detail with reference to the illustrated embodiment. As shown in FIG. 1, a refrigerant gas pump 1 has a cylinder 1a and a piston 1b fitted therein, and an inner peripheral surface of the cylinder 1a and an outer peripheral surface of the piston 1b. A known liquid lubricating material 2 such as oil is provided between the piston and the piston. At this time, a piston space 3 is formed between the upper end 1c of the cylinder 1a and the upper end 1d of the piston 1b. I have.
[0018]
The upper end portion 1c of the cylinder 1a and the lower end portion 4b of the regenerator 4 disposed above and having a regenerative heat exchanger 4a therein are connected via a refrigerant gas flow pipe 5. , The piston space 3 of the cylinder 1a communicates with the inside of the regenerator 4.
[0019]
Here, as the regenerative heat exchanger 4a, as shown in the figure, a number of thin tubes 4d are internally provided so as to be bundled in the axial direction, or a known structure in which a number of metal nets are stacked in layers. It can be used, and thereby, the liquid lubricant 2 scattered in the refrigerant gas can be collected. Of course, at this time, even if the liquid lubricant 2 adheres, the flow path of the refrigerant gas is not blocked. The regenerative heat exchanger 4a is designed.
[0020]
Next, the upper end portion 4c of the regenerator 4 is connected to the upper end portion 6b of the pulse tube 6 by a known low temperature portion 6a, and the lower end portion 6c of the pulse tube 6 at the room temperature side is an orifice valve. In the drawing, 9a is a cooling gas exchange side cooling heat exchange section provided on the refrigerant gas distribution pipe 5 and 9b is a room temperature section which is a lower end 6c of the pulse tube 6. An additional pulse tube cooling heat exchange unit, 6d indicates a gas piston.
[0021]
In the pulse tube refrigerator having the above-described configuration, in the embodiment according to the present invention, the lower end 4b of the regenerator 4, the lower end 6c of the pulse tube 6, and the lower end 8a of the buffer tank 8 are further connected. Liquid lubricant return pipes 10a, 10b, and 10c are connected between the whole or a part and an upper end 1c of the cylinder 1a of the refrigerant gas pump 1, and each of these pipes has a check valve. 11a, 11b and 11c are interposed, whereby the liquid lubricant 2 flows down in the directions of arrows 12a, 12b and 12c due to gravity and pressure difference, but the refrigerant gas in the piston space 3 and the liquid contained therein The lubricant is configured not to flow back.
[0022]
In the above embodiment, when the refrigerant gas pump 1 is operated, a low temperature is obtained in the low temperature section 6a by the adiabatic expansion of the refrigerant gas, as described in the above-described conventional example, and the low temperature side heat is provided to this. The heat exchange as the refrigerator is performed by the exchange unit 13, and by the operation, the liquid lubricant 2 of the refrigerant gas pumping device 1 enters the regenerator 4 together with the refrigerant gas through the refrigerant gas distribution pipe 5. Press-fit.
[0023]
Therefore, the regenerative heat exchanger 4a exhibits a cool storage effect, not only contributing to lowering the temperature of the refrigerant gas in the low temperature section 6a, but also the liquid lubricant 2 attached to the regenerative heat exchanger 4a as a cool storage material. Function is achieved.
[0024]
When the operation as a pulse tube refrigerator is started in this way, the liquid lubricant 2 that has entered with the refrigerant gas, regardless of whether it is in the regenerator 4 or the pulse tube 6 and the buffer tank 8, respectively. Flows downward by gravity, and this flows through the liquid lubricant return pipes 10a, 10b, 10c connected to the lower ends 4b, 6c, 8a and the check valves 11a, 11b, 11c. Then, it flows down into the piston space 3 from the upper end 1c of the cylinder 1a. Therefore, the liquid lubricant 2 is fed back between the piston 1b and the cylinder 1a, and automatic reuse is realized.
[0025]
Note that, in practice, the refrigeration gas which has a slight effect on the reduction of the refrigeration efficiency may flow through the check valves 11a, 11b and 11c without being completely blocked. In order to prevent this, the inner diameter, length, arrangement, and the like of the liquid lubricant return pipes 10a, 10b, and 10c are appropriately selected, and further, a flow control valve and a fixed orifice are separately provided with check valves 11a and 11b. , 11c is desirably provided in series.
[0026]
【The invention's effect】
Since the present invention can be configured as described above, the usable low-temperature region is limited, but it is possible to exhibit the effect of the liquid lubricant as a cold storage material in the cold storage, As a result, not only can the refrigeration capacity be improved, but it can also be operated by a piston using liquid lubricant, making it possible to use inexpensively produced oil-lubricated compressors for CFC refrigerators. Thus, a significant cost reduction can be realized. In addition, the degree of freedom in selecting a known reciprocating type, a rotary type, a scroll type, or the like is widened according to the usage mode.
[0027]
In addition, by properly installing a liquid lubricant return pipe with a check valve, the liquid lubricant that is to be pumped together with the refrigerant gas can be returned into the cylinder of the refrigerant gas pump without any effort. The liquid lubricant can be efficiently reused without requiring any extra labor.
[Brief description of the drawings]
FIG. 1 is a partially cutaway overall configuration piping diagram showing an embodiment of a piston type pulse tube refrigerator according to the present invention.
FIG. 2 shows a conventional refrigerator, in which (A) is a Stirling refrigerator, (B) is a piston-type pulse tube refrigerator, and (C) is an explanatory view of the entire longitudinal section of a valve-type pulse tube refrigerator.
FIG. 3 (A) is a conventional orifice type pulse tube refrigerator, and FIG. 3 (B) is a partially cutaway general configuration piping diagram showing a conventional piston type orifice type pulse tube refrigerator.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 refrigerant gas pump 1a cylinder 1b piston 1c upper end of cylinder 2 liquid lubricant 3 piston space 4 regenerator 4a regenerative heat exchanger 4b lower end of regenerator 4c upper end of regenerator 5 refrigerant gas distribution pipe 6 pulse tube 6a Low temperature section 6b Upper end section of pulse tube 6c Lower end section of pulse tube 7 Orifice valve 8 Buffer tank 10a Liquid lubricant return pipe 10b Liquid lubricant return pipe 10c Liquid lubricant return pipe 11a Check valve 11b Check valve 11c Check valve

Claims (1)

A piston, which operates through a liquid lubricant, is fitted into the cylinder, a refrigerant gas pump having a piston space formed between the upper end of the cylinder and the piston, and a regenerative heat exchanger installed above the refrigerant gas pump. And the lower end of the regenerator with the inside is connected by a refrigerant gas flow pipe, and the upper end of the regenerator and the upper end of the pulse tube are communicated by the low temperature part, and the room is the room temperature part of the pulse tube. The lower end portion is connected to the buffer tank via an orifice valve, and the liquid lubricant recovered in all or a part of the lower end portion of the regenerator, the lower end portion of the pulse tube, and the lower end portion of the buffer tank is provided. A piston lug using a liquid lubricant characterized by being provided with a liquid lubricant return pipe with a check valve that falls into the piston space from the upper end of the cylinder of the refrigerant gas pump. Over blanking refrigerator.

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