JP2005283026A - Cold storage type refrigerating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve refrigerating efficiency and refrigerating capacity in a cold storage type refrigerating machine such as a GM type impulse wave tube refrigerating machine or a GM refrigerating machine with a composition wherein a compression part and a refrigeration part are separated. <P>SOLUTION: The cold storage type refrigerating machine is provided with the compression part 21, the refrigeration part 12 provided with a cold-accumulator 24, a high pressure valve 22 supplying a refrigerant from the compression part 21 to the refrigeration part 12, and a low pressure valve 23 returning the refrigerant from the refrigeration part 12 to the compression part 21. The refrigerating efficiency and the refrigerating capacity are improved at the same time by providing a pressure of the refrigerant supplied from the compression part 21 to the refrigeration part 12 at 2.8MPa or more, and providing a pressure of the refrigerant returned from the refrigeration part 12 to the compression part 21 at 1MPa or more. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a regenerative refrigeration system in which a compression unit and a freezing unit are separated from each other, such as a GM type pulse tube refrigerator used as a cryogenic refrigerator or a GM refrigerator employing a Gifford-McMahon cycle. Related to the machine.

  As is well known, the cold storage type refrigerator includes a compression unit placed in a room temperature part and a freezing part constituting a low temperature part.

  That is, the refrigerant compressed by the compressor of the compression unit is led to a regenerator configured in the refrigeration unit by opening / closing of the valve or a phase difference between the compression piston and the expansion piston, and after being precooled there, The cold corresponding to the expansion work is generated, and again passes through the regenerator, rises in temperature while cooling the regenerator material to cool the refrigerant sucked in the next cycle, returns to room temperature, and is recovered by the compression unit.

  The regenerative refrigerator is operated periodically with this process as one cycle, and generates cold at the low temperature end of the freezing section.

  Typical examples of such a regenerative refrigerator include a GM type pulse tube refrigerator, a GM refrigerator, and a Stirling refrigerator.

  In the case of a Stirling refrigerator, the compression piston constituting the compression unit and the expansion piston constituting the freezing unit are operated synchronously while maintaining a specific phase difference. However, a GM type pulse tube refrigerator or GM refrigerator is used. Then, since the pulse tube and the displacer piston constituting the refrigeration unit are operated independently, a compression unit independent from the refrigeration unit can be adopted structurally.

  Therefore, in the GM type pulse tube refrigerator and GM refrigerator, various types such as a rotary type and a reciprocating type can be selected as the compressor constituting the compression unit, and the compressor can be reduced in size and height by rotating at high speed. Efficiency can also be achieved.

  Also, since the refrigeration unit is separated, vibration from the compression unit can be reduced, and it is used in various fields of cryogenic use for reasons such as good attachment to the object to be cooled and easy handling. Yes.

  Various types of GM type pulse tube refrigerators and GM refrigerators having a configuration in which the compression unit and the freezing unit are separated have been proposed as is well known. For example, a refrigerant compressed from 1.8 MPa (megapascal) to around 2 MPa is supplied to the freezing section through a high-pressure valve, and is adiabatically expanded in the freezing section, and its low temperature end is cooled to a very low temperature.

  Expansion in such a regenerative refrigerator is basically Simon expansion, and the amount of cold generated at the cold end of the freezing section (hereinafter referred to as refrigeration capacity) is in principle the pressure difference before and after expansion and the expansion volume. Since the refrigeration efficiency (= refrigeration capacity / power consumption) is inversely proportional to the pressure ratio before and after expansion, various improvements have been proposed to improve the refrigeration capacity and the refrigeration efficiency.

  For example, Patent Document 1 is an example of a GM type pulse tube refrigerator, and this configuration includes a regenerator 24 ′, a low temperature heat exchanger 25 ′, a pulse tube 26 ′, and a high temperature heat exchanger 27 ′ as shown in FIG. A refrigerating unit 12 ′ configured by sequentially connecting in series, a compression unit 21 ′, a high-pressure valve 22 ′, and a low-pressure valve 23 ′, and the regenerator 24 ′ via the high-pressure valve 22 ′ and the low-pressure valve 23 ′. And a compression unit 21 ′ are connected to each other, and a pressure vibration device 11 ′ that generates pressure fluctuations in the refrigerant inside the freezing unit 12 ′ is provided.

  Furthermore, it has a first intermediate pressure Pm1 that is an intermediate pressure between the high pressure side pressure Ph that is the discharge pressure of the compression section 21 'and the low pressure side pressure Pl that is the suction pressure, and via the first intermediate pressure buffer valve 14'. A first intermediate pressure buffer 13 ′ connected to the high temperature heat exchanger 27 ′ for adjusting the phase difference between the pressure fluctuation and the position fluctuation of the refrigerant inside the pulse tube 26 ′, and a compression section 21 ′ higher than the first intermediate pressure. Pm2 has a second intermediate pressure that is intermediate between the high-pressure side pressure Ph and the low-pressure side pressure Pl, and is connected to the high-temperature heat exchanger 27 'via the second intermediate-pressure buffer valve 16' so that the inside of the pulse tube 26 ' And a second intermediate pressure buffer 15 ′ that adjusts the phase difference between the pressure fluctuation and the position fluctuation of the refrigerant, and includes a high pressure valve 22 ′, a low pressure valve 23 ′, a first intermediate pressure buffer valve 14 ′, and a second intermediate pressure buffer. The valve 16 'is configured to open in the order of its control pressure.

  As a pressure state in the circuit in the GM type pulse tube cooler of the example of Patent Document 1, first, the high pressure side pressure Ph that is the discharge pressure of the compression unit 21 ′ is set to 2 MPa, and the low pressure that is the suction pressure. Since the side pressure Pl is set to 1 MPa, as described above, the pressure difference (Ph-Pl) between the high pressure side pressure Ph before and after expansion and the low pressure side pressure Pl proportional to the refrigeration capacity of the refrigerator is 1 MPa. The pressure ratio (Ph / Pl) involved in the refrigeration efficiency is 2.

  Further, the first intermediate pressure Pm1 that is the pressure in the first intermediate pressure buffer 13 ′ is substantially divided into three parts between 2 MPa that is the high pressure side pressure Ph of the compression portion 21 ′ and 1 MPa that is the low pressure side pressure Pl. Around the lower pressure of 1.33 MPa, the second intermediate pressure Pm2 as the pressure in the second intermediate pressure buffer 15 is equal to 2 MPa which is the high pressure side pressure Ph of the compression section 21 ′ and the low pressure side pressure Pl. The pressure is about 1.66 MPa, which is the higher pressure when 1 MPa is approximately divided into three equal parts.

  Therefore, for example, when the refrigeration cycle is advanced by opening the high pressure valve 22 ′, the low pressure valve 23 ′, the first intermediate pressure buffer valve 14 ′, and the second intermediate pressure buffer valve 16 ′ so as not to substantially overlap each other. The operation process of the refrigerant pressure at each stage of the cycle is performed under a relatively small pressure difference formed by the interposition of each adjacent intermediate pressure or the like.

  For this reason, in order to obtain a required pressure state, the amount of movement of the refrigerant flowing into and out of the low temperature end 26a ′ of the pulse tube 26 ′ from the compression unit 21 ′, the first intermediate pressure buffer 13 ′, and the second intermediate pressure buffer From 15 ′, the amount of refrigerant flowing in and out of the high-temperature end 26b ′ of the pulse tube 26 ′ is reduced.

  As the amount of refrigerant moved decreases, the load (power consumption) of the compressor 21 'is reduced, and from the pulse tube high temperature end 26b' toward the pulse tube low temperature end 26a 'due to the reduced amount of refrigerant movement. So-called regenerative heat based on the heat loss of the pulse tube 26 'based on the amount of heat entering (enthalpy) and the amount of heat (enthalpy) flowing from the regenerator high temperature end 24b' to the regenerator low temperature end 24c 'without being stored in the regenerator 24'. Loss is also improved, the refrigeration efficiency of the GM pulse tube refrigerator 10 ′ is improved, and the refrigeration capacity is also improved.

  Furthermore, the high pressure valve 22 ′, the low pressure valve 23 ′, the first intermediate pressure buffer valve 14 ′, and the second intermediate pressure buffer valve 16 ′ are thermodynamically operated by opening them under a relatively small pressure difference. Loss based on the opening operation of the valve under unequal pressure, which is an irreversible process, so-called valve loss is also reduced, and the load (power consumption) of the compression unit 21 ′ is reduced.

  As described above, in Patent Document 1, as the pressure state in the circuit of the GM type pulse tube refrigerator 10 ′, the high pressure side pressure Ph before expansion is set to 2 MPa, and the low pressure side pressure Pl after expansion is set to 1 MPa. The pressure difference (Ph-Pl) before and after expansion proportional to the refrigerating capacity is 1 MPa, and the pressure ratio (Ph / Pl) involved in the refrigerating efficiency is 2, but the first intermediate pressure buffer 13 ′ and the second medium Providing the pressure buffer 15 ′ reduces the amount of refrigerant movement and valve loss, thereby improving the refrigeration efficiency and the refrigeration capacity.

  Next, Patent Document 2 is a regenerative refrigerator having a configuration in which a compression unit and a refrigeration unit are separated by taking a GM refrigerator as an example, and a high-pressure side path and a low-pressure side path of the compression unit include pressure regulating valves. And the pressure regulating valve is configured to open when the pressure in the low-pressure side path is equal to or lower than a predetermined pressure, and to bypass the refrigerant from the high-pressure side path to the low-pressure side path. Yes.

  Therefore, until the pressure in the low-pressure side passage is reduced to a predetermined pressure by the pressure adjusting valve, the refrigerant in the high-pressure side passage is not bypassed to the low-pressure side passage, and all the refrigerant compressed by the compressor is So that a high refrigerating capacity can be stably maintained.

  In Patent Document 2, as an example of the pressure state in the GM type refrigerator circuit, the high pressure side pressure that is the discharge pressure of the compressor is about 2 MPa, the low pressure side pressure that is the suction pressure is about 0.5 MPa, and Since the set pressure of the pressure regulating valve is set to about 0.4 MPa, the high pressure side pressure Ph (= 2 MPa) before and after expansion proportional to the refrigeration capacity of the refrigerator and the pressure Pl (= 0. The pressure difference (Ph-Pl) of 5 MPa) is (2 MPa-0.5 MPa), that is, around 1.5 MPa, and the pressure ratio (Ph / Pl) before and after expansion involved in refrigeration efficiency is (2 MPa / 0.5 MPa) That is, around 4.

Since the set pressure of the pressure regulating valve is set to around 0.4 MPa, the refrigerant in the high-pressure side path is not bypassed to the low-pressure side path until the low-pressure side pressure becomes 0.4 MPa. All the refrigerants compressed in step (3) are stably supplied to the refrigeration unit and can be operated while maintaining the refrigeration capacity.
Japanese Patent No. 3314769 JP 2000-266416 A

  By the way, the GM pulse tube refrigerator and the GM refrigerator having a configuration in which the compression unit and the freezing unit are separated are placed in a low temperature unit and a compression unit having a compressor that pressurizes a refrigerant in a room temperature unit. It is composed of a refrigeration unit that has a regenerator and expands the refrigerant, and normal-temperature high-pressure refrigerant that has been compressed and radiated by the compressor is led to the regenerator through a valve and precooled, and then insulated at the cold end of the refrigeration unit It expands and is cooled to a very low temperature.

  As described above, the GM pulse tube refrigerator and the GM refrigerator in which the compression unit and the freezing unit are separated in this manner generate cold due to irreversible expansion called Simon expansion as described above. Inefficiency occurs due to expansion, and the refrigeration efficiency is lower than the ideal Carnot efficiency.

  Therefore, in order to suppress the decrease in the refrigeration efficiency (referred to as η) of this type of refrigerator, in principle, it is necessary to reduce the pressure ratio before and after the expansion, and now, before the expansion supplied from the compressor If the high pressure side pressure is Ph and the low pressure side pressure after expansion is Pl, the pressure ratio before and after expansion (Ph / Pl) needs to be as small as possible.

  On the other hand, in order to improve the refrigerating capacity (Q) of this type of refrigerator, in the case of an ideal gas, in principle, the refrigerating capacity Q is equal to the expansion work of the refrigerant, and the high-pressure side pressure before expansion is set to Ph, Assuming that the low-pressure side pressure after expansion is Pl, the refrigeration capacity Q is the product of the expansion volume V and the pressure difference (Ph-Pl) before and after expansion, that is, Q = V (Ph-Pl). In order to increase a certain Q = V (Ph−Pl), when the expansion volume V is constant, it is necessary to increase the pressure difference before and after expansion (Ph−Pl).

  Therefore, in order to increase the refrigeration efficiency η and simultaneously improve the refrigeration capacity Q, it is necessary to reduce the pressure ratio (Ph / Pl) and simultaneously increase the pressure difference (Ph-Pl). It is necessary to increase the high-pressure side pressure Ph of the refrigerant.

  However, in conventional GM type pulse tube refrigerators and GM refrigerators in which the compression unit and the refrigeration unit are separated, for example, an air conditioning compressor with a relatively low pressure resistance using, for example, a chlorofluorocarbon refrigerant R22 is used. , There are problems in the pressure resistance of each part of the refrigerator and the efficiency of the regenerator, and as described in Patent Document 1 and Patent Document 2, the high-pressure side pressure Ph before expansion is designed and manufactured at around 2 MPa. It was.

  Therefore, even if an attempt is made to increase the pressure difference (Ph−Pl) in order to improve the refrigerating capacity Q = V (Ph−Pl), the high pressure side pressure Ph before expansion remains around 2 MPa. There was a problem that the pressure difference (Ph-Pl) did not become about 1.5 MPa or more, and the refrigeration capacity could not be increased by increasing the pressure difference (Ph-Pl).

  As for the refrigeration efficiency η, the high-pressure side pressure Ph remained around 2 MPa. Therefore, in order to secure the refrigeration capacity Q = V (Ph-Pl), increase the pressure difference (Ph-Pl) as described above. As a result, the low pressure side pressure Pl has to be reduced, and as a result, the pressure ratio before and after expansion (Ph / Pl) increases as the low pressure side pressure Pl decreases, resulting in inefficiency associated with irreversible expansion. There was a problem that it became large and refrigeration efficiency became low.

  The present invention has been made in view of such circumstances, and in a regenerative refrigerator such as a GM type pulse tube refrigerator or a GM refrigerator in which a compression unit and a freezing unit are separated, the refrigerating capacity and the refrigerating efficiency are provided. It is a technical problem to improve the above simultaneously.

The invention of claim 1 made to solve the technical problem described above,
A compressor having a compressor for pressurizing the refrigerant; a refrigeration unit having a regenerator to expand the refrigerant; a high-pressure valve for supplying the refrigerant from the compressor to the refrigeration unit; and the refrigerant from the refrigeration unit to the compressor. A regenerative refrigerator having a low pressure valve to be recovered, wherein the pressure of the refrigerant supplied from the compression unit to the refrigerating unit via the high pressure valve is 2.8 MPa or more. It is.

  In order to solve the above technical problem, it is preferable that the refrigerant pressure recovered from the refrigeration unit to the compression unit via the low-pressure valve is 1 MPa or more.

  In order to solve the above technical problem, as in claim 3, the refrigeration unit is configured as a GM type pulse refrigerator including a regenerator and a pulse tube, and a plurality of medium pressures connected to the pulse tube. A buffer valve and a plurality of medium pressure buffers connected to the plurality of medium pressure buffer valves, respectively, and the high pressure valve, the low pressure valve, and the plurality of medium pressure buffer valves are opened in the order of their control pressures. It is preferable to do so.

  Moreover, when solving the said technical subject, it is preferable to comprise as a GM refrigerator with which a freezing part expands multistage like Claim 4.

  According to the first aspect of the present invention, in a regenerative refrigerator such as a GM type pulse tube refrigerator or a GM refrigerator, the compression unit and the freezing unit are separated and connected by a high pressure valve and a low pressure valve. By increasing the high-pressure side pressure of the refrigerant supplied from the unit to the refrigeration unit via the high-pressure valve from about 2 MPa of the prior art to 2.8 MPa or more, by reducing the pressure ratio before and after expansion, the refrigeration capacity Q and Both the refrigeration efficiency η can be improved at the same time.

  That is, now, assuming that the high pressure side pressure before expansion is Ph and the low pressure side pressure after expansion is Pl, when the pressure difference before and after expansion (Ph-Pl) proportional to the refrigerating capacity Q is the same pressure difference, As the high-pressure side pressure Ph increases, the pressure ratio (Ph / Pl) can be reduced to increase the refrigeration efficiency η, and the pressure ratio (Ph / Pl) before and after expansion, which is inversely proportional to the refrigeration efficiency η. In the case of the same pressure ratio, the pressure difference before and after expansion (Ph-Pl) can be increased by the increase in the high-pressure side pressure Ph, and the refrigerating capacity Q can be improved.

  For example, now, when the expansion volume V, the pressure ratio (Ph / Pl) is 2 of the same pressure ratio as in Patent Document 1, and the high pressure side pressure Ph is 3 MPa as an example of 2.8 MPa or more of the present embodiment, The refrigerating capacity Q = V (Ph−Pl) in the ideal state when the high pressure side pressure Ph in Patent Document 1 is 2 MPa is compared.

  First, since the refrigerating capacity Q1 = V (Ph−Pl) in an ideal state when the high pressure side pressure Ph is 3 MPa, the pressure ratio (Ph / Pl) is 2, and the low pressure side pressure Pl is 1.5 MPa, The pressure difference (Ph−Pl) before and after expansion is (3 MPa−1.5 MPa) = 1.5 MPa. Now, for comparison, if the unit of each physical quantity is the same and omitted, the refrigerating capacity Q1 = V (Ph−Pl) = 1.5 × V.

  On the other hand, the refrigerating capacity Q2 = V (Ph−Pl) in the ideal state when the high pressure side pressure Ph is 2 MPa in Patent Document 1 has a pressure ratio (Ph / Pl) of 2 and the low pressure side pressure Pl is 1 MPa. Therefore, the pressure difference before and after expansion (Ph−Pl) is (2 MPa−1 MPa) = 1 MPa. For the sake of comparison, if the units of the physical quantities are the same, the refrigerating capacity Q2 = V (Ph−Pl) = 1 × V.

  Thus, when the pressure ratio (Ph / Pl) before and after expansion is set to 2 in the same manner, the refrigerating capacity Q1 when the high pressure side pressure Ph is 3 MPa and the high pressure side pressure Ph in Patent Document 1 are 2 MPa. Comparing the refrigerating capacity Q2, it can be seen that the refrigerating capacity is improved by (Q1-Q2) = (1.5V-V) = 0.5V as the high-pressure side pressure Ph is increased.

  According to the invention described in claim 2, by setting the low pressure side pressure of the refrigerant recovered from the refrigeration unit to the compression unit to 1 MPa or more, for example, the high pressure side pressure supplied from the compression unit before expansion is set to Ph, Assuming that the low-pressure side pressure recovered in the compression section after expansion is Pl, even if the high-pressure side pressure Ph of the refrigerant is set to 2.8 MPa or more, the low-pressure side pressure Pl after expansion is also 1 MPa or more. The pressure ratio (Ph / Pl) can be set to a small value of 2.8 or less.

  In other words, when cold generation is performed by irreversible expansion as in a regenerative refrigerator, in order to improve the refrigeration efficiency η, it is necessary to reduce the pressure ratio before and after expansion as described above. Even if the high pressure side pressure Ph is set to 2.8 MPa or more in order to improve the refrigerating capacity Q as described above, the low pressure side pressure Pl is also 1 MPa or more, so the pressure ratio (Ph / Pl) is 2. A small value of 8 or less can be set, and high refrigeration efficiency can be secured.

  For example, when the pressure difference (Ph−Pl) before and after expansion is 1.5 MPa and the same refrigeration capacity Q is to be secured, the high pressure side pressure Ph is 3 MPa as an example of 2.8 MPa or more of the present embodiment. When comparing the pressure ratio in the ideal state when the high pressure side pressure Ph is 2 MPa as in Patent Document 1, when the high pressure side pressure Ph is 3 MPa, the low pressure side pressure Pl is 1.5 MPa, and the pressure before and after expansion The ratio (Ph / Pl) is 2.

  On the other hand, when the high-pressure side pressure Ph is 2 MPa, the pressure difference (Ph-Pl) is 1.5 MPa, so the low-pressure side pressure Pl is 0.5 MPa, and the pressure ratio (Ph / Pl) before and after expansion is 4, which is significantly larger than the pressure ratio of 2 when the high-pressure side pressure Ph is 3 MPa.

  Thus, when the pressure difference before and after expansion (Ph-Pl) is 1.5 MPa, the pressure ratio (Ph / Pl) when the high pressure side pressure Ph is 3 MPa, and the high pressure side pressure Ph in Patent Document 1 is 2 MPa. When the pressure ratio (Ph / Pl) is compared, the pressure ratio (Ph / Pl) is 2 when the high-pressure side pressure Ph is 3 MPa, and 4 when the high-pressure side pressure Ph is 2 MPa. Since the higher the Ph, the smaller the pressure ratio, the refrigeration loss due to the irreversible expansion is reduced and the refrigeration efficiency is improved.

  According to the third aspect of the present invention, in the GM pulse tube refrigerator having a pulse tube in the refrigeration unit, the GM pulse tube refrigerator includes the intermediate pressure buffer connected to the pulse tube by an intermediate pressure buffer valve, and the intermediate pressure buffer valve When the refrigeration cycle is advanced with the high-pressure valve, the low-pressure valve, and each of the intermediate-pressure buffer valves open so that they do not substantially overlap, The refrigerant pressure change in each operation stage can be performed under a relatively small pressure ratio formed by the adjacent intermediate pressure of each operation stage in the cycle, and is supplied from the compression section. The pressure on the high pressure side of the refrigerant is increased to about 2.8 MPa or more from the conventional value of about 2 MPa, and the pressure difference between the high pressure side pressure before and after expansion, which is proportional to the refrigeration capacity, and the low pressure side pressure is now made the same. Compare A relatively small the pressure ratio which is formed by a neighboring intermediate pressure in each operation stage in the cycle, amount that increased the high side pressure, can be reduced.

  Accordingly, in order to obtain a required pressure state in each operation stage described in Patent Document 1, the amount of refrigerant flowing from the compression section to the low temperature end of the pulse tube, and from each intermediate pressure buffer to the high temperature end of the pulse tube. In addition to reducing the load (power consumption) of the compression section because the amount of refrigerant that flows in and out is reduced, the high pressure valve, the low pressure valve, and each intermediate pressure buffer valve are also relatively small in this embodiment. Since the valve can be opened under the pressure ratio, each loss associated with the pressure ratio, such as loss due to valve opening under non-equal pressure, which is a thermodynamically irreversible process, so-called valve loss, is reduced. Accordingly, the load (power consumption) of the compression unit is reduced, and the refrigeration efficiency is improved.

  According to the fourth aspect of the present invention, in the GM refrigerator in which the refrigeration unit includes an expansion chamber and a displacer piston, the refrigeration unit including the expansion chamber and the displacer piston is configured to expand in multiple stages at the same time. As a result, the loss associated with the movement of the refrigerant under non-uniform pressure and non-isothermal temperature, which is a thermodynamically irreversible process in the regenerator, as in the conventional patent document 2, the so-called regenerator loss is reduced. However, in this embodiment, the high-pressure side pressure and the low-pressure before and after expansion, in which the refrigerating capacity is proportional, are further increased by increasing the high-pressure side pressure of the refrigerant supplied from the compression unit from about 2 MPa to about 2.8 MPa. When the pressure difference with the side pressure is the same, the pressure ratio before and after expansion becomes small, so the refrigerant moves under unequal pressure, which is a thermodynamically irreversible process in the regenerator. It is possible to reduce the losses based, correspondingly, the load of the compression unit (power consumption) is reduced, refrigeration efficiency is improved.

  Hereinafter, an embodiment of a GM type pulse tube refrigerator embodying the present invention will be described. First intermediate pressure buffer connected to a pulse tube by a first intermediate pressure buffer valve and second intermediate pressure buffer connected by a second intermediate pressure buffer valve This will be described with reference to FIGS.

  FIG. 1 is a schematic configuration diagram showing an embodiment of a GM type pulse tube refrigerator according to the present invention. A GM type pulse tube refrigerator 10 in this embodiment includes a pressure vibration device 11, a freezing unit 12, and a first unit. An intermediate pressure buffer 13 and a first intermediate pressure buffer valve 14, a second intermediate pressure buffer 15 and a second intermediate pressure buffer valve 16, and a control device 17 are provided.

  The pressure vibration device 11 generates pressure vibration in a refrigerant such as helium filled in the GM type pulse tube refrigerator 10, and includes a compression unit 21, a high pressure valve 22 and a low pressure valve 23.

  The discharge port 21 a of the compression unit 21 is connected to the refrigeration unit 12 via a high-pressure valve 22, while the suction port 21 b is connected to the refrigeration unit 12 via a low-pressure valve 23.

  In the pressure vibration device 11, the high pressure valve 22 and the low pressure valve 23 are controlled to be opened and closed by the control device 17 at a predetermined timing, so that the pressure in the refrigerant in the refrigeration unit 12 of the GM pulse tube refrigerator 10 is increased. Generate vibration.

  In the present embodiment, the high-pressure side pressure Ph that is the discharge pressure of the compression unit 21 is set to 2.8 MPa or more. However, in the following description, the high-pressure side pressure Ph is 2.8 MPa or more. One example is 3 MPa.

  In the present embodiment, the low pressure side pressure Pl that is the suction pressure of the compression unit 21 is set to 1 MPa or more, but in the following description, the pressure ratio (Ph / Pl) between the high pressure side pressure Ph and the low pressure side pressure Pl. ) Is set to 1.5 MPa as an example of 1 MPa or more so that the refrigerating capacity can be compared as 2 as in Patent Document 1.

  The refrigeration unit 12 includes a regenerator 24, a low temperature heat exchanger 25, a pulse tube 26, and a high temperature heat exchanger 27 that are sequentially connected in series.

  The regenerator 24 is filled with a regenerator material 24a made of, for example, stainless steel or phosphor bronze, and has a regenerator high temperature end 24b on the high temperature side and a regenerator low temperature end 24c on the low temperature side as described above. ing.

  The regenerator high temperature end 24 b is connected to the pressure vibration device 11, and the regenerator low temperature end 24 c is connected to the low temperature heat exchanger 25.

  The regenerator 24 gradually cools the refrigerant as it progresses toward the low-temperature heat exchanger 25 side, and conversely when the refrigerant proceeds toward the pressure vibration device 11 side. Heat exchange with the refrigerant is performed so as to gradually warm up.

  The low-temperature heat exchanger 25 connected to the regenerator low-temperature end 24c of the regenerator 24 is a low-temperature generator.

  This low-temperature heat exchanger 25 has, for example, a large number of regular holes along the flow direction of the refrigerant, for example, copper in order to efficiently take heat from the object to be cooled in contact with the low-temperature heat exchanger 25. It is formed of a material having excellent thermal conductivity such as.

  The pulse tube 26 connected to the low temperature heat exchanger 25 has a pulse tube low temperature end 26a and a pulse tube high temperature end 26b at one end (low temperature heat exchanger 25 side) and the other end (high temperature heat exchanger 27 side), respectively. It has a hollow tube.

  The pulse tube 26 is formed of a material having a low thermal conductivity such as stainless steel, for example, in order to prevent the heat on the high temperature end 26b side of the pulse tube from being transferred to the low temperature heat exchanger 25 by heat conduction. Yes.

  The high-temperature heat exchanger 27 connected to the pulse tube 26 has a large number of regular holes along the flow direction of the refrigerant, for example, and is formed of a material having excellent thermal conductivity such as copper. .

  The high-temperature heat exchanger 27 is for cooling the pulse tube high-temperature end 26b by releasing the heat of the refrigerant flowing through the outside to the outside. Connected to the pressure buffer valve 16.

  The first intermediate pressure buffer valve 14 is interposed between the refrigeration unit 12 and the first intermediate pressure buffer 13 and is controlled to be opened and closed by the control device 17 at a predetermined timing. Adjust the pressure fluctuation and position fluctuation of the refrigerant inside.

  The first intermediate pressure buffer 13 is formed, for example, to have a volume larger than the volume in the refrigeration unit 12, and the refrigerant therein has a high pressure side pressure Ph (discharge pressure: 3 MPa) of the compression unit 21. ) And the low pressure side pressure Pl (suction pressure: 1.5 MPa), the first intermediate pressure Pm1, which is the lower pressure (≈2 MPa) when approximately divided into three equal parts.

  The second intermediate pressure buffer valve 16 is interposed between the refrigeration unit 12 and the second intermediate pressure buffer 15, and is controlled to open and close at a predetermined timing by the control device 17, so that the refrigeration unit is similarly provided. The pressure fluctuation and position fluctuation of the refrigerant in 12 are adjusted.

  The second intermediate pressure buffer 15 is formed, for example, to have a volume equivalent to that of the first intermediate pressure buffer 13, and the refrigerant therein has a high pressure side pressure Ph (discharge pressure: 3 MPa) of the compression unit 21. ) And the low pressure side pressure Pl (suction pressure: 1.5 MPa), which is a first intermediate pressure Pm2 that is the higher pressure (≈2.5 MPa) when approximately divided into three equal parts.

  The control device 17 opens and closes the high pressure valve 22, the low pressure valve 23, the first intermediate pressure buffer valve 14, and the second intermediate pressure buffer valve 16 at predetermined timings.

  Next, the operation of the GM type pulse tube refrigerator 10 in this embodiment will be described with reference to FIG.

  FIG. 2 is a graph showing operating states and pressure states of the on-off valves in the embodiment of the GM type pulse tube refrigerator 10 according to the present invention.

  The operation of one cycle of the GM pulse tube refrigerator 10 has six stages (first stage a, second stage b, third stage c, fourth stage d, fifth stage e, Each stage is divided corresponding to the open / closed states of the high pressure valve 22, the low pressure valve 23, the first intermediate pressure buffer valve 14, and the second intermediate pressure buffer valve 16.

  In FIG. 2, the open / close state of the high pressure valve 22, the low pressure valve 23, the first intermediate pressure buffer valve 14, and the second intermediate pressure buffer valve 16, and the refrigeration unit 12 in each of the six operation stages in one cycle. The internal pressure state is shown.

  In FIG. 2, the thick solid line drawn for each of the high pressure valve 22, the low pressure valve 23, the first intermediate pressure buffer valve 14, and the second intermediate pressure buffer valve 16 indicates the open state, and the thin solid line indicates the closed state. It shall be shown.

  Hereinafter, the operation in one cycle of the GM pulse tube refrigerator 10 of the present embodiment will be described for each of the six stages.

  First stage a (pre-compression process): The first intermediate pressure buffer valve 14 is opened almost simultaneously with the low pressure valve 23 being closed, and the high pressure valve 22 and the second intermediate pressure buffer valve 16 are kept closed. It is.

  In this state, the refrigerant in the first intermediate pressure buffer 13 held at the first intermediate pressure Pm1 (≈2 MPa) flows into the inside from the high-temperature end 26b of the pulse tube via the first intermediate pressure buffer valve 14. .

  In this case, since the first intermediate pressure buffer 13 and the pulse tube 26 are brought into communication with each other via the first intermediate pressure buffer valve 14 having a small pressure loss, the pressure in the pulse tube 26 is quickly reduced to the low pressure side pressure. : Increased from Pl (1.5 MPa) to the first intermediate pressure Pm1 (≈2 MPa), which is the pressure of the first intermediate pressure buffer 13.

  Second stage b (intermediate compression process): The second intermediate pressure buffer valve 16 is opened almost simultaneously with the first intermediate pressure buffer valve 14 being closed.

In this state, the refrigerant in the second intermediate pressure buffer 15 maintained at the second intermediate pressure Pm2 (≈2.5 MPa) flows into the inside through the intermediate pressure buffer valve 16 from the high-temperature end 26b of the pulse tube.

  Also in this case, since the second intermediate pressure buffer 14 and the pulse tube 26 are brought into communication with each other via the second intermediate pressure buffer valve 16 with a small pressure loss, the pressure in the pulse tube 26 is promptly changed to the first intermediate pressure buffer. The pressure increases from the pressure Pm1 (≈2 MPa) to the second intermediate pressure Pm2 (≈2.5 MPa), which is the pressure of the second intermediate pressure buffer 15.

  Third stage c (late compression process): The high pressure valve 22 is opened almost simultaneously with the second intermediate pressure buffer valve 16 being closed.

  In this state, the refrigerant flows from the discharge port 21a of the compression unit 21 having the high pressure side pressure Ph (3 MPa) through the high pressure valve 22 into the pulse tube 26 from the low temperature end 26a of the pulse tube, and the pressure of the pulse tube 26 is increased. Increases to the high pressure side pressure Ph (3 MPa).

  Fourth stage d (pre-expansion process): The second intermediate pressure buffer valve 16 is in an open state almost simultaneously with the high pressure valve 22 being closed.

  In this state, the refrigerant from the second intermediate pressure buffer 15 that has flowed into the pulse tube 26 flows out from the pulse tube high temperature end 26 b into the second intermediate pressure buffer 15 via the second intermediate pressure buffer valve 16. .

  In this case, since the second intermediate pressure buffer 15 and the pulse tube 26 are brought into communication with each other via the second intermediate pressure buffer valve 16 having a small pressure loss, the pressure in the pulse tube 26 is quickly increased to the high pressure side pressure. : Reduced from Ph (3 MPa) to the second intermediate pressure Pm2 (≈2.5 MPa), which is the pressure of the second intermediate pressure buffer 15.

  Due to this pressure drop, the refrigerant in the pulse tube 26 adiabatically expands and the temperature drops.

  Fifth stage e (mid-expansion middle stage): The first intermediate pressure buffer valve 14 is opened almost simultaneously with the second intermediate pressure buffer valve 16 being closed.

  In this state, the refrigerant from the first intermediate pressure buffer 13 flowing into the pulse tube 26 further flows out from the high temperature end 26b of the pulse tube into the first intermediate pressure buffer 13 through the first intermediate pressure buffer valve 14. .

  Also in this case, since the first intermediate pressure buffer 13 and the pulse tube are brought into communication with each other via the first intermediate pressure buffer valve 14 having a small pressure loss, the pressure in the pulse tube 26 is quickly increased to the second intermediate pressure buffer 26. The pressure decreases from the pressure Pm2 (≈2.5 MPa) to the first intermediate pressure Pm1 (≈2 MPa), which is the pressure of the first intermediate pressure buffer 13.

  Due to this pressure drop, the refrigerant in the pulse tube 26 adiabatically expands and the temperature drops.

  Sixth stage f (expansion late process): When the first intermediate pressure buffer valve 14 is closed, the low pressure valve 23 is opened almost simultaneously.

  In this state, the refrigerant from the regenerator high-temperature end 24b of the regenerator 24 is sucked into the suction port 21b of the compression unit 21 via the low-pressure valve 23, and the pressure in the pulse tube 26 is low-pressure side pressure Pl (1. 5 MPa).

  At this time, the refrigerant whose temperature has decreased due to adiabatic expansion in the pulse tube 26 moves to the low-temperature heat exchanger 25 to exchange heat with the low-temperature heat exchanger 25, and the first stage a (compression Return to the state of the previous process.

  As described above, a series of operations from the first stage a to the sixth stage f is set as one cycle, and by repeating this, a cryogenic temperature is efficiently generated in the low-temperature heat exchanger 25 of the pulse tube refrigerator 10.

  In the present embodiment, as described above, the high-pressure side pressure Ph that is the discharge pressure of the compression unit 21 is set to 2.8 MPa or more (3 MPa in the description example), and the pressure ratio before and after the expansion of the refrigerant is lowered to perform irreversible expansion. In the conventional GM type pulse tube refrigerator or GM refrigerator, the compression unit 21 has a structure in which the compression unit and the refrigeration unit are separated from each other. The highest pressure Ph, which is the discharge pressure, is at most around 2 MPa at most even as described in Patent Document 1 and Patent Document 2 described above.

For example, in the GM type pulse tube refrigerator in Patent Document 1, the basic configuration as the GM type pulse tube refrigerator 10 ′ is the same as that of the embodiment of the present invention as shown in the schematic configuration diagram of FIG. The pressure conditions of the high-pressure side pressure Ph of the part, the low-pressure side pressure Pl of the compression part, the pressure Pm1 of the first intermediate pressure buffer, and the pressure Pm2 of the second intermediate pressure buffer are as follows. As shown in the graph showing the state, it is set lower than in the embodiment of the present invention.

  That is, as described above, the high pressure side pressure Ph of the GM type pulse tube refrigerator in Patent Document 1 is 2 MPa, the low pressure side pressure Pl is 1 MPa, and the first intermediate pressure Pm1 that is the pressure of the first intermediate pressure buffer is The first intermediate pressure Pm2 that is 1.33 MPa and the pressure of the second intermediate pressure buffer is 1.66 MPa.

  Based on FIG. 3, FIG. 4, the pressure state for every operation | movement in 1 cycle of this GM type pulse tube refrigerator is demonstrated below.

  FIG. 3 is a schematic diagram showing the GM type pulse tube refrigerator 10 ′ of Patent Document 1, and the basic configuration is the same as that of the present embodiment, and therefore the reference numerals of the respective portions are the same as those shown in FIG. 'Is added to the reference symbol.

  FIG. 4 is a graph showing operating states and pressure states of the on-off valves of the GM type pulse tube refrigerator 10 ′ of Patent Document 1.

  In FIG. 4, as in FIG. 2 shown in the description of the present embodiment, the high pressure valve 22 ′, the low pressure valve 23 ′, the first intermediate pressure buffer valve 14 ′, and the second medium in each operation stage within one cycle. The open / closed state of the pressure buffer valve 16 ′ and the pressure state in the refrigeration unit 12 ′ are shown. For each of the high pressure valve 22 ′, the low pressure valve 23 ′, the first intermediate pressure buffer valve 14 ′, and the second intermediate pressure buffer valve 16 ′. The thick solid line drawn in (1) indicates the open state, and the thin solid line indicates the closed state.

Operations other than those relating to the pressure state in one cycle of the GM type pulse tube refrigerator 10 ′ of Patent Document 1 are the same as in the present embodiment, the high pressure valve 22 ′, the low pressure valve 23 ′, and the first intermediate pressure buffer valve 14. The six stages (first stage a ′, second stage b ′, third stage c ′, fourth stage d ′, second stage) divided according to the open / closed states of the “and second intermediate pressure buffer valve 16”. 5 stage e ′ and 6th stage f ′), the description of the valve open / close state and the refrigerant movement state in each stage is omitted, but in the freezing unit 12 ′ in each stage different from the present embodiment. The pressure state is as follows.

  First stage a ′ (pre-compression process): When the low pressure valve 23 ′ is closed, the first intermediate pressure buffer valve 14 ′ is opened almost simultaneously, and the high pressure valve 22 ′ and the second intermediate pressure buffer valve 16 ′ are closed. This is a state in which the state is maintained.

  In this state, the pressure in the refrigeration unit 12 ′ immediately increases from the low pressure side pressure: Pl (1 MPa) to the first intermediate pressure Pm1 (≈1.33 MPa) that is the pressure of the first intermediate pressure buffer 13 ′. .

  Second stage b '(intermediate compression process): The second intermediate pressure buffer valve 16' is opened almost simultaneously with the first intermediate pressure buffer valve 14 'being closed.

  In this state, the pressure in the refrigeration unit 12 ′ is promptly changed from the first intermediate pressure Pm1 (≈1.33 MPa) to the second intermediate pressure Pm2 (≈1.66 MPa) which is the pressure of the second intermediate pressure buffer 15. Rise.

  Third stage c ′ (late compression process): The high pressure valve 22 ′ is opened almost simultaneously with the second intermediate pressure buffer valve 16 ′ being closed.

  In this state, the pressure in the refrigeration unit 12 ′ increases to the high-pressure side pressure Ph (discharge pressure: 2 MPa).

  Fourth stage d ′ (pre-expansion process): The second intermediate pressure buffer valve 16 ′ is in an open state almost simultaneously with the high pressure valve 22 ′ being closed.

  In this state, the pressure in the refrigeration unit 12 ′ immediately decreases from the high-pressure side pressure Ph (2 MPa) to the second intermediate pressure Pm2 (≈1.66 MPa) that is the pressure of the second intermediate pressure buffer 15 ′.

  Due to this pressure drop, the refrigerant in the pulse tube 26 'expands adiabatically and drops in temperature.

  Fifth stage e ′ (intermediate expansion process): The first intermediate pressure buffer valve 14 is opened almost simultaneously with the second intermediate pressure buffer valve 16 ′ being closed.

  In this state, the pressure in the refrigeration unit 12 ′ quickly decreases from the second intermediate pressure Pm2 (≈1.66 MPa) to the first intermediate pressure Pm1 (≈1.33 MPa) that is the pressure of the first intermediate pressure buffer 13. .

  Due to this pressure drop, the refrigerant in the pulse tube 26 'expands adiabatically and drops in temperature.

  Sixth stage f ′ (expansion late stage process): The low pressure valve 23 ′ is opened almost simultaneously with the first intermediate pressure buffer valve 14 ′ being closed.

  In this state, the pressure in the refrigeration unit 12 ′ decreases to the low pressure side pressure Pl (suction pressure: 1.5 MPa).

  At this time, the refrigerant whose temperature has decreased due to adiabatic expansion in the pulse tube 26 'moves to the low-temperature heat exchanger 25', so that heat is exchanged with the low-temperature heat exchanger 25 '. It returns to the state of a ′ (first compression stage process).

  As described above, a series of operations from the first stage a 'to the sixth stage f' is set as one cycle, and by repeating this, a cryogenic temperature is generated in the low-temperature heat exchanger 25 'of the pulse tube refrigerator 10'.

  That is, in the GM type pulse tube refrigerator 10 ′ of Patent Document 1, the high pressure side pressure Ph that is the discharge pressure of the compressor 21 ′ is set to 2 MPa, and the low pressure side pressure Pl that is the suction pressure is set to 1 MPa. In addition, the first intermediate pressure buffer 13 ′ has a first intermediate pressure Pm1 (≈1...) Which is a lower pressure when the high pressure side pressure Ph and the low pressure side pressure Pl of the compression portion 21 ′ are substantially divided into three equal parts. 33 MPa), the second intermediate pressure buffer 15 ′ has a second intermediate pressure Pm2 (≈1) that is the higher pressure when the high pressure side pressure Ph and the low pressure side pressure Pl of the compression section 21 ′ are divided into approximately three equal parts. .66 MPa).

  On the other hand, in the GM pulse tube refrigerator 10 of the present embodiment, as described in FIGS. 1 and 2, the high-pressure side pressure Ph that is the discharge pressure of the compression unit 21 is set to 3 MPa, and the suction pressure The low pressure side pressure Pl is set to 1.5 MPa, and the first intermediate pressure buffer 13 has a lower pressure when the pressure between the high pressure side pressure Ph and the low pressure side pressure Pl of the compression unit 21 is substantially divided into three equal parts. The first intermediate pressure Pm1 (≈2 MPa) and the second intermediate pressure buffer 15 is the higher pressure when the space between the high pressure side pressure Ph and the low pressure side pressure Pl of the compression section 21 is approximately divided into three equal parts. 2 Medium pressure Pm2 (≈2.5 MPa).

  Therefore, as described above, in order to increase the refrigerating capacity, it is necessary to increase the differential pressure before and after expansion (Ph-Pl). However, in the GM pulse tube refrigerator of Patent Document 1, the pressure before expansion is increased. Since the high-pressure side pressure remained at around 2 MPa, when the low-pressure side pressure Pl was lowered, the compression ratio (Ph / Pl) before and after expansion also increased and the refrigeration efficiency tended to decrease, and the difference between before and after expansion The pressure (Ph-Pl) was also limited by Pl and could not be increased to about 1.5 MPa or more.

  On the other hand, in the present embodiment, the high pressure side pressure before expansion is around 2 MPa, whereas the high pressure side pressure is set as high as 2.8 MPa or more. Even under the condition of (Ph / Pl), the differential pressure before and after expansion (Ph-Pl) can be greatly increased, so that the refrigerating capacity can be improved and the refrigerating efficiency can also be improved.

  In addition, it has also been confirmed by experiments by the inventors of the GM type pulse tube refrigerator of the present embodiment that the improvement in the refrigerating capacity and the refrigerating efficiency is more remarkable as the high-pressure side pressure before expansion is higher. Therefore, the experimental results will be explained below.

  FIG. 5 shows a case where the discharge pressure of the compression portion, which is the high-pressure side pressure, is changed to 1.61 MPa, 1.80 Mpa, 2.00 MPa, 2.21 Mpa, and 2.40 MPa, respectively, in the prototype of the present embodiment. The graph which showed the result of having measured the refrigerating capacity in 77K. FIG. 6 is a graph showing the results of measuring the refrigeration efficiency at 77K (= 77K refrigeration capacity / power consumption) when the discharge pressure of the compression unit is changed from the above pressure.

  5 and 6, when the discharge pressure of the compression section is 1.61 MPa, the refrigerating capacity is 73.30 W, the refrigerating efficiency is 0.0278, and when the discharge pressure of the compression section is 1.80 MPa, the refrigerating capacity is: 84.62 W, refrigeration efficiency: 0.0291, refrigeration capacity: 95.91 W when the compression section discharge pressure is 2.00 MPa, refrigeration efficiency: 0.0299, refrigeration when the compression section discharge pressure is 2.21 MPa When the capacity is 107.07 W, the refrigeration efficiency is 0.0304, and the discharge pressure of the compression unit is 2.40 MPa, the refrigeration capacity is 117.03 W and the refrigeration efficiency is 0.0308. Thus, it can be seen that as the discharge pressure of the compression section increases as the high-pressure side pressure, the refrigeration capacity increases in a linear function, and the refrigeration efficiency also tends to increase.

  For example, according to this result, the high pressure side pressure Ph is set at 2 MPa in Patent Document 1 in the prior art, but in the prototype of this embodiment, the refrigerating capacity under this high pressure side pressure Ph (2 MPa) is Refrigeration efficiency stays around 96W and refrigeration efficiency is around 0.03. For example, when the high pressure side pressure Ph is set to 3 MPa as in this embodiment, the refrigeration capacity is improved to around 150W and the refrigeration efficiency is raised to around 0.0316, respectively. You can see that

  Further, as in the embodiment, for example, even when the high-pressure side pressure Ph is set to 2.8 MPa, the refrigerating capacity is about 135 W and the refrigerating efficiency is about 0.0314, which is improved as compared with the case where the high-pressure side pressure Ph is set to 2 MPa. You can see that

  Next, in the present embodiment, as described above, the low-pressure side pressure Pl that is the suction pressure of the compression unit 21 is set to 1 MPa or higher (1.5 MPa in the explanation example) to improve the refrigerating efficiency and the refrigerating capacity. However, the low-pressure side pressure Pl after expansion in a GM type pulse tube refrigerator or GM refrigerator in which a compression unit and a refrigeration unit of this type are separated is also disclosed in Patent Document 1 and Patent Document 2. As shown, the high pressure side pressure Ph before expansion is. In some cases, the pressure remained below about 2 MPa, and in order to ensure the refrigerating capacity, it was necessary to increase the differential pressure before and after expansion (Ph-Pl), so even the highest one was set to less than 1 MPa.

  That is, in the GM type pulse tube refrigerator, it is necessary to reduce the pressure ratio in order to suppress the decrease in efficiency due to irreversible expansion as described above.

  In this embodiment, since the high-pressure side pressure Ph before expansion is set to 2.8 MPa or more, in order to reduce the pressure ratio before and after expansion (Ph / Pl), after expansion, which is recovered from the refrigeration unit to the compression unit By setting the low-pressure side pressure Pl of about 1 MPa or more, the pressure ratio can be set to a small value of about 3 or less even if the high-pressure side pressure Ph before expansion is set high in order to improve the refrigerating capacity. It is possible to secure high refrigeration efficiency by reducing the pressure ratio even under high refrigeration capacity.

  Refrigerating efficiency is improved by reducing the pressure ratio before and after expansion (Ph / Pl). In principle, when the pressure ratio Ph / Pl before and after expansion is approximately 3 or more, the rate of decrease in refrigeration efficiency is large. The rate of improvement in the refrigeration efficiency increases as the value approaches from 3 to 1, and this tendency has been confirmed in experiments by the inventors at a refrigeration temperature of 77K.

  As described above, the GM pulse tube refrigerator in the present embodiment recovers the high pressure side pressure Ph of the refrigerant supplied from the compression unit 21 from the conventional value of about 2 MPa to 2.8 MPa or more and to the compression unit 21. The low pressure side pressure Pl to be set to 1 MPa or more, the pressure vibration device 11, the refrigeration unit 12, the first intermediate pressure buffer 13, the first intermediate pressure buffer valve 14, the second intermediate pressure buffer 15, and the second 2 The intermediate pressure buffer valve 16 and the control device 17 are configured so that the high pressure valve 22 and the low pressure valve 23 of the pressure vibration device 11 are opened so as not to overlap each other as described above, and this refrigeration cycle is advanced. Thus, the refrigerant pressure change at each operation stage in the refrigeration cycle is performed at a relatively small pressure ratio formed by the adjacent intermediate pressure of each operation stage, etc. It is to improve.

  That is, in order to achieve a required pressure state in each operation stage, the amount of movement of refrigerant flowing from the compression section to the low temperature end of the pulse tube and the amount of movement of refrigerant flowing from each intermediate pressure buffer to the high temperature end of the pulse tube In addition to reducing the load (power consumption) of the compression unit, the present embodiment further includes a high pressure valve, a low pressure valve, and each intermediate pressure buffer valve in each operation stage of the refrigeration cycle. By opening under a relatively small pressure ratio, each loss associated with the pressure ratio such as loss due to valve opening under unequal pressure, which is a thermodynamically irreversible process, so-called valve loss, is As a result, the load (power consumption) of the compression unit is reduced correspondingly, and the refrigeration efficiency and the refrigeration capacity are improved.

  In the GM pulse refrigerator 10 of the present embodiment, the first intermediate pressure buffer 13 connected by the first intermediate pressure buffer valve 14 and the second intermediate pressure connected to the intermediate pressure buffer connected to the pulse tube 26 by the intermediate pressure buffer valve. Two examples of the second intermediate pressure buffer 15 communicated by the buffer valve 16 are shown. However, even if there are three or more intermediate pressure buffers each connected by the intermediate pressure buffer valve, Even if only one is provided, this embodiment is applied.

  In the above description, the GM type pulse tube refrigerator has been described as an example of the regenerator type refrigerator. However, in the same manner as this GM type pulse tube refrigerator, the compressor unit placed in the room temperature part and the low temperature part are respectively regenerators. The present embodiment can be applied to a GM refrigerator that includes a refrigeration unit including a multistage expansion chamber including a displacer piston and is configured to expand at the same time.

  Embodiments in the GM refrigerator will be described below with reference to FIGS.

  FIG. 7 shows a schematic configuration diagram showing an embodiment of a GM refrigerator having a two-stage expansion configuration, and FIG. 8 shows operating states of the on-off valve and each displacer piston of the GM refrigerator having the two-stage expansion configuration. And shows the pressure status of the freezer.

  The GM refrigerator 30 in the present embodiment includes the pressure vibration device 11, the freezing unit 31, and the driving unit 48.

  The pressure vibration device 11 includes a compression unit 21 having a discharge port 21a and a suction port 21b, a high pressure valve 22 connected to the discharge port 21a side of the compression unit 21, and a low pressure connected to the suction port 21b side of the compression unit 21. And a valve 23. The high pressure valve 22 is connected to the discharge port 21a of the compression unit 21 by a high pressure pipe 28a, and the low pressure valve 23 is connected to the suction port 21b of the compression unit 21 by a low pressure pipe 28b. In this example, the high-pressure valve 22 and the low-pressure valve 23 are constituted by a rotary valve, and the high-pressure valve 22 and the low-pressure valve 23 are alternately opened and closed by rotation of the rotor (not shown). repeat.

  The refrigeration unit 31 includes a first stage cylinder 41, a second stage cylinder 42, a first stage displacer piston 43, a second stage displacer piston 44, and a drive mechanism 48.

  As shown in the figure, a first-stage displacer piston 43 is accommodated in the first-stage cylinder 41. Both the first stage cylinder 41 and the first stage displacer piston 43 are formed in a cylindrical shape in this example, and the axial distance of the first stage cylinder 41 is longer than the axial distance of the first stage displacer piston 43. Has been. The diameter of the first stage cylinder 41 is designed to be slightly larger than the diameter of the first stage displacer piston 43. Accordingly, the first-stage displacer piston 43 can reciprocate in the axial direction within the first-stage cylinder 41.

  A gap space 37 is formed between the rear end side (the lower end side in the drawing) of the first stage displacer piston 43 and the first stage cylinder 41. As shown in the drawing, one end of a connection pipe 29 communicates with the gap space 37. The other end of the connection pipe 29 is connected to the high pressure valve 22 and the low pressure valve 23. Therefore, pressure fluctuations due to the exclusive opening and closing of the high-pressure valve 22 and the low-pressure valve 23 are transmitted to the gap space 37 via the connecting pipe 29.

  The first stage displacer piston 43 is formed with a first stage displacer case 43a, and a first stage regenerator 45 is accommodated in the first stage displacer case 43a.

  The first-stage displacer case 43a is formed with a rear surface side communication hole 43b and a side surface side communication hole 43c. The rear surface side communication hole 43b is formed on the rear end surface side (the lower end surface side in the drawing) of the first stage displacer case 43a. Accordingly, the gap space 37 is configured to communicate with the first stage regenerator 45 inside the first stage displacer piston 43 via the rear side communication hole 43b. On the other hand, the side surface side communication hole 43c is formed on the upper side of the side surface of the first stage displacer case 43a. Therefore, the first expansion space 35 formed between the first stage cylinder 41 and the front end face side (the upper end face side in the figure) of the first stage displacer piston 43 is the first stage displacer case 43a and the first stage cylinder 41. The first stage regenerator 45 is communicated with the first side regenerator 45 through the side surface gap and the side surface side communication hole 43c. A piston ring 47 is fitted on the outer periphery of the first-stage displacer case 43a. The piston ring 47 blocks communication between the gap space 37 and the first expansion space 35.

  A second-stage displacer piston 44 is connected to the front end surface (the upper surface in the drawing) of the first-stage displacer piston 43. The second stage displacer piston 44 is accommodated in the second stage cylinder 42. Both the second stage cylinder 42 and the second stage displacer piston 44 are formed in a cylindrical shape in this example, and the axial distance of the second stage cylinder 42 is designed to be longer than the axial distance of the second stage displacer piston 44. ing. The diameter of the second stage cylinder 42 is designed to be slightly larger than the diameter of the second stage displacer piston 44. Accordingly, the second stage displacer piston 44 can be reciprocated in the axial direction within the second stage cylinder 42.

  The outer casing of the second stage displacer piston 44 is formed by a second stage displacer case 44a, and a second stage regenerator 46 is accommodated in the second stage displacer case 44a. Furthermore, a rear-side communication path 44b and a side-side communication hole 44c are formed in the second-stage displacer case 44a. The rear side communication passage 44b is formed so that the rear end (the lower end surface in the drawing) of the second stage displacer case 44a communicates with the first expansion space 35. Therefore, the first expansion space 35 is configured to communicate with the second-stage regenerator 46 inside the second-stage displacer piston 44 through the rear-side communication hole 44b. On the other hand, the side surface side communication hole 44c is formed on the upper side in the figure of the side surface of the second-stage displacer case 44a. Therefore, the second expansion space 36 formed between the second stage cylinder 42 and the front end face side (the upper end face side in the figure) of the second stage displacer piston 44 is the second stage displacer case 44 a and the second stage cylinder 42. Are connected to the second-stage regenerator 46 inside the second-stage displacer piston 44 through the side-surface gap and the side-side communication hole 44c.

  A room temperature plate 32 is provided on the rear end face side of the first stage cylinder 41, a first cold stage 33 is provided on the front end face side (that is, the outer peripheral side of the first expansion space 35), and the front end face side of the second stage cylinder 42 ( That is, the second cold stage 34 is attached to the outer peripheral side of the second expansion space 36. The first and second cold stages 33 and 34 transmit the cold generated in the expansion spaces 35 and 36 to the object to be cooled, and both are made of a material such as copper having a good thermal conductivity.

  A connecting member 49 is attached to the rear end side of the first stage displacer piston 43. One end of the connecting member 49 is connected to the first stage displacer piston 43 as described above, and the other end protrudes from the room temperature plate 32 to the outside. The reciprocating drive means 48 is connected to the other end of the connecting member 49.

  In this example, as the reciprocating drive means 48, a drive motor, a disc coaxially connected to the output shaft of the drive motor, one end is attached to the outer peripheral side of the disc, and the other end is a connecting member 49. The example comprised including the connecting rod connected to is shown. Therefore, when the drive motor is driven, the rotational motion by the drive motor is converted into reciprocating motion by the connecting rod, and this reciprocating motion is transmitted to the first stage displacer piston 43 via the connecting rod and connecting member 49. As described above, since the second stage displacer piston 44 is connected to the front end side of the first stage displacer piston 43, both the displacer pistons 43, 44 reciprocate in the displacer cases 41, 42 simultaneously.

  In this example, the high-pressure valve 22 and the low-pressure valve 23 are constituted by rotary valves. Therefore, by operating the rotary valve in conjunction with the rotation of the drive motor in the reciprocating drive means 48, the high-pressure valve 22 and the low-pressure valve have a constant timing with respect to the reciprocating movement of the first-stage and second-stage displacer pistons 43, 44. The valve 23 can be opened and closed exclusively.

  In this configuration, the refrigerant supplied from the compression unit 21 is opened and closed with a phase difference from the operation of the first-stage displacer piston 43 and the second-stage displacer piston 44 formed in two stages, and It is led to the first-stage regenerator 45 and the second-stage regenerator 46 through the low-pressure valve 23, and after precooling, it corresponds to the expansion work of the first-stage displacer piston 43 and the second-stage displacer piston 44. The cold is generated and the temperature rises again while cooling the regenerator material through the regenerators 45 and 46, and the temperature returns to room temperature and is recovered by the compression unit 21. The first cold stage operates periodically with this process as one cycle. Cold is generated in the 33 and the second cold stage 34.

  Further, in this configuration, the high pressure side pressure Ph before expansion of the refrigerant supplied from the compression unit 21 to the freezing unit 31 is set to 2.8 MPa or more with respect to a value around 2 MPa set in the conventional Patent Document 2 or the like. In addition, the low pressure side pressure Pl after expansion of the refrigerant recovered from the freezing unit 31 to the compression unit 21 is set to 1 MPa or more.

  The operation of the present embodiment will be described below with reference to FIGS.

  In the GM refrigerator 30 shown in FIG. 7 and FIG. 8, the high pressure side pressure Ph supplied from the compression unit 21 to the freezing unit 31 and the low pressure side pressure Pl recovered from the freezing unit 31 to the compression unit are In the following description, the pressure difference before and after expansion (Ph-Pl) proportional to the refrigerating capacity and Patent Document 2 is set to the same 1.5 MPa, and the high pressure side pressure Ph is set to 2.8 MPa or more in order to compare the refrigerating efficiency. For example, 3 MPa is set as an example, and the low pressure side pressure Pl is set to 1.5 MPa as an example of 1 MPa or more.

  In FIG. 8, the thick solid line drawn for each of the high-pressure valve 22 and the low-pressure valve 23 indicates the open state, and the thin solid line indicates the closed state.

  Based on FIG. 8, the operation | movement and pressure state in 1 cycle of the GM refrigerator 30 in this embodiment are demonstrated.

  In FIG. 8, the operation of one cycle of the GM refrigerator 30 includes four stages (first stage A, second stage B, third stage C, and fourth stage D) described below. The stages are classified according to the open / closed states of the high pressure valve 22 and the low pressure valve 23 and the displacement states of the first stage displacer piston 43 and the second stage displacer piston 44 in the first expansion space 35 and the second expansion space 36. The

  First stage A: the displacers 43 and 44 are starting to descend from the top dead center to the bottom dead center with the high pressure valve 22 open and the low pressure valve 23 closed.

  In this state, the refrigerant flows into the refrigeration unit 31 from the compression unit 21 via the high-pressure valve 22, and the pressure of the refrigeration unit increases to 3 MPa.

  Second stage B: The displacer pistons 43 and 44 are lowered to the bottom dead center while the high pressure valve 22 is opened and the low pressure valve 23 is closed.

  In this state, in the refrigeration unit, the displacer pistons 43 and 44 move to move the first expansion space 35 and the second expansion space 36 to the high-pressure refrigerant cooled by the first regenerator 45 and the second regenerator 46, respectively. Is filled.

  Third stage C: The displacers 43 and 44 are starting to rise from the bottom dead center to the top dead center with the high pressure valve 22 closed and the low pressure valve 23 opened.

  In this state, the low-pressure valve 23 is opened, the pressure in the refrigeration unit 31 is reduced to 1.5 MPa, the refrigerant in the first expansion space 35 and the second expansion space 36 is adiabatically expanded, and the temperature is decreased.

  Fourth stage D: The displacer pistons 43 and 44 are moved to the top dead center while the high pressure valve 22 is closed and the low pressure valve 23 is opened.

  As the displacers 43 and 44 move, the refrigerant in the first expansion space 35 and the second expansion space 36 whose temperature has decreased cools the first cold stage 33 and the second cold stage 34, respectively, and the first regenerator 45 and It is recovered by the compression unit 21 through the second regenerator 46.

  As described above, in the present embodiment, the high pressure side pressure Ph is set to 3 MPa, the low pressure side pressure Pl is set to 1.5 MPa, and a series of operations from the first stage A to the fourth stage D is set as one cycle, and this is repeated. Therefore, a cryogenic temperature is generated in the low-temperature heat exchangers 33 and 34 of the GM refrigerator 30.

  Therefore, for example, the pressure difference (Ph-Pl) (high pressure side pressure Ph: 3 MPa, low pressure side pressure Pl: 1.5 MPa) proportional to the refrigerating capacity in this embodiment is set to 1.5 MPa (high pressure side) as in Patent Document 2. Comparing the pressure ratio (Ph / Pl) when the pressure Ph: 2 MPa and the low pressure side pressure Pl: 0.5 MPa) is compared with the pressure ratio (Ph / Pl) of 4 in Patent Document 2, the embodiment In this example, the pressure ratio (Ph / Pl) is 2, and the refrigeration efficiency is improved by the amount the pressure ratio is reduced.

  That is, as described above, the refrigeration capacity in the ideal state of the regenerative refrigerator is represented by the product of the expansion volume V and the pressure difference before and after expansion (Ph-Pl). The GM refrigerator in this embodiment is also patented. While the conventional high pressure side pressure Ph before expansion as represented by Document 2 was around 2 MPa, by setting the high pressure side pressure Ph before expansion to 2.8 MPa or more, the differential pressure (Ph -Pl) is the same, the pressure ratio (Ph / Pl) is reduced and the refrigeration efficiency is improved, and if the pressure ratio (Ph / Pl) is the same, the pressure difference before and after expansion (Ph-Pl) ) Can be greatly increased, and the refrigerating capacity can be improved.

  Furthermore, in the GM refrigerator of this embodiment, the refrigeration unit is expanded at the same time by the first expansion space 35 and the second expansion space 36 including the first-stage displacer piston 43 and the second-stage displacer piston 44. It is configured to reduce loss due to refrigerant movement under non-isostatic pressure and non-isothermal temperature, which is a thermodynamically irreversible process in the regenerator, so-called regenerator loss, but in this embodiment, By increasing the high-pressure side pressure of the refrigerant supplied from the compression unit from about 2 MPa to about 2.8 MPa, the pressure difference between the high-pressure side pressure and the low-pressure side pressure before and after expansion where the refrigeration capacity is proportional is made the same. In this case, the pressure ratio before and after expansion decreases as the high-pressure side pressure increases. In addition to reducing valve loss based on the pressure difference, the thermodynamically irreversible process in the regenerator There loss based on the coolant transfer at unequal pressure can also be reduced, correspondingly further compressed portions load (power consumption) is reduced, refrigeration efficiency is improved.

  In the GM refrigerator of the present embodiment, an example of two-stage expansion is shown, but the present invention is also applicable to one-stage expansion or multistage expansion of three or more stages.

It is the structure schematic which shows embodiment in the GM type pulse tube refrigerator concerning this invention. It is a graph which shows each on-off valve operating condition and pressure state in embodiment in the GM type pulse tube refrigerator concerning this invention. It is the structure schematic which shows the conventional GM type | mold pulse tube refrigerator. It is a graph which shows the operating condition of each on-off valve of the conventional GM type pulse tube refrigerator, and the pressure state of a freezing part. It is a graph which shows the relationship between the refrigerating capacity in 77K in the embodiment with the GM type pulse tube refrigerator concerning this invention, and the discharge pressure of a compression part. It is a graph which shows the relationship between the 77K freezing efficiency and discharge pressure of a compression part in embodiment with the GM type pulse tube refrigerator concerning this invention. It is a schematic block diagram which shows embodiment with the GM refrigerator concerning this invention. It is a graph which shows the operating condition of the on-off valve in the embodiment in the GM refrigerator concerning this invention, and the pressure state of a freezing part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... GM type | mold pulse tube refrigerator 11 ... Pressure vibration apparatus 12 ... Freezing part 13 ... 1st intermediate pressure buffer 14 ... 1st intermediate pressure buffer valve 15 ... 2nd intermediate pressure Buffer 16 ··· Second intermediate pressure buffer valve 21 ··· Compression portion 21a ··· Discharge port 21b ··· Suction port 22 ··· High pressure valve 23 ··· Low pressure valve 24a ··· Regenerator 24b ··· High temperature of regenerator End 24c ··· Cold storage cold end 25 ··· Low temperature heat exchanger 26 ··· Pulse tube 26a · · Pulse tube cold end 26b · · Pulse tube high temperature end 27 ··· High temperature heat exchanger

Claims (4)

  A compressor having a compressor for pressurizing the refrigerant; a refrigeration unit having a regenerator for expanding the refrigerant; a high-pressure valve for supplying the refrigerant from the compressor to the refrigeration unit; and the refrigerant from the freezer to the compressor. A regenerative refrigerator having a low-pressure valve to be recovered, wherein the pressure of the refrigerant supplied from the compression unit to the refrigerating unit via the high-pressure valve is 2.8 MPa or more.   2. The regenerative refrigerator according to claim 1, wherein the pressure of the refrigerant recovered from the refrigeration unit to the compression unit through a low-pressure valve is 1 MPa or more.   In any one of Claims 1 and 2, while the refrigeration unit is configured as a GM type pulse refrigerator having a regenerator and a pulse tube, a plurality of medium pressure buffer valves connected to the pulse tube, A plurality of medium pressure buffers connected to each of the plurality of medium pressure buffer valves, wherein the high pressure valve, the low pressure valve, and the plurality of medium pressure buffer valves are opened in order of their control pressures. A regenerative refrigerator.   The regenerative refrigerator according to any one of claims 1 and 2, wherein the refrigeration unit is configured as a GM refrigerator having multistage expansion.

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