CN108106039B - Multi-channel shunt vascular refrigerator - Google Patents

Abstract

The invention relates to a multi-channel bypass pulse tube refrigerator, including a cold head, a compression mechanism and a phase modulator, wherein n stages are arranged in the cold head, and each stage of the cold head is composed of a radiator, a regenerator, and a cooling capacity exchanger. The heater and the pulse tube are connected in sequence. The compression mechanism has n compression chambers, and each compression chamber is connected to each cold head respectively. The cold ends of the tubes are connected, the pulse tube of the last stage is connected with the phase modulator, and a phase-modulating gas reservoir is arranged between at least n-1 stage cold heads and corresponding compression chambers. Compared with the prior art, the present invention introduces a phase-adjusting air reservoir between the cold head and the compression chamber, so that phase modulation and work distribution can be carried out separately. The work distribution follows the scavenging volume ratio, and the scavenging volume is made Large, so that the scavenging volume of one of the compression chambers meets the requirements of phase modulation, and when the scavenging volume of other compression chambers is excessive, use the phase modulation gas storehouse to balance the remaining part, which not only meets the requirements of phase modulation, but also satisfies the distribution of work question.

Description

Multiple bypass pulse tube refrigerator

technical field

The invention relates to the technical field of refrigerators, in particular to a multi-path bypass pulse tube refrigerator.

Background technique

In the multi-path bypass pulse tube refrigerator, the expansion work of the pulse tubes at all levels is finally collected together to the room temperature end, and an inertia tube can be used at the room temperature end. Because it is an inertial tube, compared with multiple inertial tubes, the heat transfer loss and friction loss are small, so that a better phase adjustment effect can be obtained. Due to the existence of the bypass, the DC component is difficult to avoid, and the suppression of the DC component is very complicated from the perspective of engineering application. A method to eliminate the DC component structurally is to use stepped pistons to divide the cylinder into several cylinders, each stage uses an independent regenerator, and each cylinder supplies air to each stage. This structure eliminates the DC component theoretically, but there are problems of phase modulation and work distribution. Theoretically, the distribution ratio of compression work to the first stage and the second stage is related to the scavenging volume ratio of the first stage and the second stage piston. From the perspective of phasing, the phasing of each stage requires the scavenging volume of the corresponding cylinder to make the phase difference between the air flow and the pressure at the cold end of the regenerator optimal. Generally speaking, the occasions where work distribution and phase adjustment are satisfied at the same time are very small. Therefore, although the multi-channel bypass pulse tube refrigerator is the most compact form of multi-stage pulse tube refrigerator, it has not yet become the main multi-stage form.

Due to the use of an inertial tube, there is excess expansion work to be recovered under high power conditions, and the phase modulation is still insufficient under low power conditions. Therefore these problems need to be overcome. The use of stepped pistons theoretically eliminates the DC component, but when using gap seals, measures still need to be taken to control the existence of the DC component caused by tiny leaks.

Contents of the invention

The object of the present invention is to provide a multi-channel bypass pulse tube refrigerator with a phase modulation function in order to overcome the above-mentioned defects in the prior art.

The purpose of the present invention can be achieved through the following technical solutions:

A multi-path bypass pulse tube refrigerator, including a cold head, a compression mechanism and a phase modulator, wherein the cold head is provided with n stages, and each stage of the cold head is composed of a radiator, a regenerator, a cooling heat exchanger and The pulse tubes are connected in sequence. The compression mechanism has n compression chambers, each compression chamber is connected to each cold head respectively, and the high temperature end of the pulse tube of the nth cold head is connected to the n-1th cold head. The low-temperature end of the pulse tube of the head is connected, the high-temperature end of the first-stage pulse tube is connected with the phase modulator, and a phase-modulating gas reservoir is set between at least n-1 cold heads and corresponding compression chambers, n≥2 , and is a positive integer.

n is preferably 2 or 3, which is the most common form of secondary cold head or tertiary cold head.

The phase-adjusting gas storage may be the dead volume between the cold head and the compression chamber, or the connecting pipe therebetween.

Further, the phase modulator is composed of an inertial tube and an inertial tube gas reservoir connected in sequence, and the pulse tube of the first-stage cold head is connected with the inertial tube.

The phase adjuster can also be in other forms, such as choosing a small-hole gas storage type phase adjuster, a two-way inlet type phase adjuster or a room temperature push piston type phase adjuster.

Further, in the compression mechanism, a compression chamber is formed by a stepped piston and a stepped cylinder, and a piston ring groove is provided at the lower part of the stepped piston, so that the gap sealing length between the stepped piston and the stepped cylinder is controllable. Or, the compression mechanism is composed of a stepped piston and a stepped cylinder to form a compression chamber, and the stepped cylinder is provided with a cylinder ring groove, so that the gap sealing length between the stepped piston and the stepped cylinder is controllable. Or, the compression mechanism is formed by a step piston and a step cylinder to form a compression chamber, the bottom of the step piston is provided with a piston ring groove, and at the same time, the step cylinder is provided with a cylinder ring groove, so that the gap between the step piston and the step cylinder The gap seal length is controllable.

Furthermore, the inertial tube gas storage is connected with one of the compression chambers to recover part of the expansion work.

Further, in addition to having n compression chambers, the compression mechanism is also provided with a back chamber opposite to the compression chamber. The cavity can be a compression cavity at the other end of the shaft of the linear motor, or a double-acting working cavity formed by a back cavity of the stepped piston to recover part of the expansion work.

Further, in addition to having n compression chambers, the compression mechanism is also provided with a back chamber opposite to the compression chamber, and the inertia tube air reservoir is connected to the back chamber of the compression mechanism, and the back chamber can be in a straight line A compression chamber at the other end of the shaft of the motor, or a double-acting working chamber formed by a back chamber of the stepped piston. Its working principle is to input work to the inertial tube, which can enhance the phase modulation ability of the inertial tube by inputting work to the inertial tube when the phase modulation of the inertial tube is insufficient, thereby improving the cooling effect.

n=2, specifically a two-stage multi-channel bypass pulse tube refrigerator, the cold head is composed of the first-stage cold head and the second-stage cold head, the first-stage cold head is composed of the first-stage radiator, and the first-stage heat recovery The second-stage cold head is composed of the second-stage radiator, the second-stage first heat regenerator, and the second-stage second heat regenerator. The second-stage cooling heat exchanger and the second-stage pulse tube are connected in sequence; the high-temperature end of the second-stage pulse tube is connected to the low-temperature end of the first-stage pulse tube; the second-stage first regenerator is connected to the first-stage The airflow channel between the second-stage regenerators is cooled by the first-stage cooling heat exchanger; the inertia tube is connected to the high-temperature end of the first-stage pulse tube; the compression mechanism is composed of a stepped piston and a stepped cylinder to form the first compression chamber and The second compression chamber; the first compression chamber is connected to the first-stage radiator of the first-stage cold head, and there is a first phase-adjusting gas reservoir between the first compression chamber and the first-stage radiator of the first-stage cold head; The second compression chamber is connected to the second-stage radiator of the second-stage cold head, and there is a second phase-adjusting gas reservoir between the second compression chamber and the second-stage radiator of the second-stage cold head.

n=3, specifically a three-stage multi-channel bypass pulse tube refrigerator, the cold head is composed of the first-stage cold head, the second-stage cold head and the third-stage cold head, and the first-stage cold head is composed of the first-stage radiator , the first-stage regenerator, the first-stage cooling heat exchanger, and the first-stage pulse tube are connected in sequence, and the second-stage cold head is composed of the second-stage radiator, the second-stage first regenerator, and the second-stage cold head The second-stage regenerator, the second-stage cooling heat exchanger, and the second-stage pulse tube are connected in sequence, and the third-stage cold head is composed of the third-stage radiator, the third-stage first regenerator, and the second-stage cold head. The third-stage second regenerator, the third-stage third regenerator, the third-stage cooling heat exchanger, and the third-stage pulse tube are connected in sequence; the high-temperature end of the third-stage pulse tube is connected to the second-stage pulse tube The low-temperature end is connected, and the high-temperature end of the second-stage pulse tube is connected with the low-temperature end of the first-stage pulse tube; The volume heat exchanger is cooled, and the airflow channel between the third-stage second regenerator and the third-stage third regenerator is cooled by the second-stage cold heat exchanger, and the second-stage first regenerator and the second The airflow channel between the second regenerators of the first stage is cooled by the first-stage cooling heat exchanger; the inertia tube is connected to the high-temperature end of the first-stage pulse tube; the compression mechanism is composed of a stepped piston and a stepped cylinder to form the first compression chamber, the second The second compression chamber and the third compression chamber, the first compression chamber is connected with the first stage radiator of the first stage cold head, and there is a first adjustment between the first compression chamber and the first stage radiator of the first stage cold head Phase gas storehouse; the second compression chamber is connected with the second-stage radiator of the second-stage cold head, and there is a second phase-adjusting gas storehouse between the second compression chamber and the second-stage radiator of the second-stage cold head. The three compression chambers are connected to the third-stage cold head, and there is a third phase-adjusting gas reservoir between the third compression chamber and the third-stage radiator of the third-stage cold head.

Compared with the prior art, the present invention introduces a phase-adjusting gas reservoir between the cold head and the compression chamber, so that the distribution of phase adjustment and work can be carried out separately. The distribution of work follows the scavenging volume ratio, and the scavenging volume is enlarged so that the scavenging volume of one of the compression chambers meets the requirements of phase modulation. Here, the phase-modified gas reservoir refers to a cavity with a certain volume. This not only meets the requirements of phase modulation, but also satisfies the problem of work distribution.

Description of drawings

Fig. 1 is a schematic structural diagram of a two-stage multi-path bypass pulse tube refrigerator in Embodiment 1;

Fig. 2 is a schematic structural diagram of a coaxial two-stage multi-channel bypass pulse tube refrigerator in embodiment 2;

Fig. 3 is a schematic structural diagram of a three-stage multi-channel bypass pulse tube refrigerator in embodiment 3;

Fig. 4 is a schematic structural diagram of a coaxial three-stage multi-channel bypass pulse tube refrigerator in embodiment 4;

Fig. 5 is a schematic structural diagram of a two-stage multi-path bypass pulse tube refrigerator using stepped pistons to recover work in Example 5;

Fig. 6 is a schematic structural diagram of a two-stage multi-channel bypass pulse tube refrigerator using a motor back cavity piston to recover work in embodiment 6;

Fig. 7 is a schematic structural diagram of a two-stage multi-channel bypass pulse tube refrigerator using a motor back cavity piston to input work to an inertia tube in embodiment 7;

Fig. 8 is a schematic structural diagram of a two-stage multi-channel bypass pulse tube refrigerator using the motor back cavity to input work to the inertial tube in embodiment 8;

Fig. 9 is a schematic structural view of the controllable sealing length in embodiment 9;

Figure 10 is a schematic structural view of the controllable sealing length in Embodiment 10;

Figure 11 is a schematic structural view of the controllable sealing length in Embodiment 11;

Fig. 12 is a schematic structural view of the controllable sealing length in embodiment 12.

Labels in the figure: 100, cold head, 10, first-stage cold head, 11, first-stage pulse tube, 12, first-stage radiator, 13, first-stage regenerator, 14, first-stage cooling capacity exchange Heater, 20, second stage cold head, 21, second stage pulse tube, 22, second stage radiator, 231, second stage first regenerator, 232, second stage second regenerator, 24 , the second-stage cooling heat exchanger, 30, the third-stage cold head, 31, the third-stage pulse tube, 32, the third-stage radiator, 331, the third-stage first regenerator, 332, the third-stage first heat exchanger Second regenerator, 333, third stage third regenerator, 34, third stage cooling heat exchanger, 40, phase modifier, 41, inertia tube, 42, inertia tube gas storage, 50, compression mechanism, 51. First compression chamber, 52. Second compression chamber, 53. Third compression chamber, 54. Stepped piston, 541. Piston ring groove, 5455. Gap seal, 55. Stepped cylinder, 551. Short ring groove of cylinder, 552 , cylinder long ring groove, 56, drive mechanism, 57, back cavity, 58 is the second piston, 59 is the second cylinder, 15, the first phase-modulating gas storehouse, 25, the second phase-modulating gas storehouse, 35, the third Phasing gas storage.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example 1

The two-stage multi-channel bypass pulse tube refrigerator has a structure as shown in FIG. 1 , and is composed of a compression mechanism 50 , a cold head 100 and a phase modulator 40 . The cold head 100 is composed of the first-stage cold head 10 and the second-stage cold head 20; 1. The first-stage pulse tubes 11 are connected in sequence; the second-stage cold head 20 is composed of a second-stage radiator 22, a second-stage first regenerator 231, a second-stage second regenerator 232, a second-stage The cooling heat exchanger 24 and the second-stage pulse tube 21 are connected in sequence; the high-temperature end of the second-stage pulse tube 21 is connected to the low-temperature end of the first-stage pulse tube 11; the second-stage first regenerator 231 is connected to the second-stage The gas flow passage between the second stage heat exchanger 232 passes through the first stage cold heat exchanger 14 but does not communicate with the first stage cold heat exchanger 14 so that the gas flowing through it is cooled so that the second stage The heat loss of the second-stage first regenerator 231 is balanced by the first-stage cooling capacity, so that more cooling capacity is obtained at the second-stage cooling capacity heat exchanger 24; the phase modulator 40 is composed of an inertial tube 41 and an inertial tube Gas storehouse 42 forms. The inertia tube 41 is connected to the high-temperature end of the first-stage vessel 11; the compression mechanism 50 is composed of a stepped piston 54 and a stepped cylinder 55 to form a first compression chamber 51 and a second compression chamber 52; the first compression chamber 51 and the first-stage cold head The first-stage radiator 12 of 10 is connected, and there is a first phase-adjusting gas storehouse 15 between the first-stage radiator 12 of the first-stage cold head 10 and the first-stage compression chamber 51; the second-stage compression chamber 52 and the second-stage The second-stage radiator 22 of the cold head 20 is connected, and there is a second phase-adjusting gas storage 25 between the second compression chamber 52 and the second-stage radiator 22 of the second-stage cold head 20 .

When working, the stepped piston 54 reciprocates up and down driven by the driving mechanism, thereby generating pressure fluctuations and generating reciprocating gas flow in the cold head 100, the gas dissipates heat at the first-stage radiator 12 and the second-stage radiator 22, and Cooling capacity is obtained at the first-stage cooling heat exchanger 14 and the second-stage cooling heat exchanger 24. Generally, the operating temperature of the first-stage cooling heat exchanger 14 is 80K, and the second-stage cooling heat exchanger 24 works The temperature is 20K, and the specific cooling temperature and cooling capacity vary according to different applications. The gas expands at the cold end of the pulse tube to do work and cool down. After the expansion work is transmitted to the inertial tube, the gas inside oscillates to produce phase modulation and is lost in the environment in the form of heat. If loss is not considered, theoretically, the pressure of the first compression chamber 51 is the same as that of the second compression chamber 52, and the output work is determined by the scavenging volume ratio. In the regenerative refrigerator, the loss control of the regenerator is the key factor to improve the refrigeration efficiency. The phase difference between the airflow and the pressure at the cold end of the regenerator has an optimal value to minimize the loss of the regenerator. The inertial tube produces an airflow that is 90 degrees to the pressure and plays the role of phase modulation. Since it is a common inertial tube, how to distribute it to the first-stage pulse tube 11 and the second-stage pulse tube 21 so that the airflow and pressure at the cold end of the regenerator The optimal phase difference depends on the volume of the regenerator, phase-modulating gas storage and the working chamber of the compression mechanism. Due to the introduction of the phase-modulating gas store, the ratio of the scavenging volume of the first compression chamber 51 and the second compression chamber 52 can be designed according to the distribution ratio of the work, and the design of one of the volumes can be designed according to the phase-modulation optimum design, and the other The volume is larger than the optimal volume of phase adjustment, and the excess part is balanced by the phase adjustment gas storage. Therefore, in this embodiment, there may be one phase-modifying gas store, that is to say, only one of the first phase-modifying gas store 15 or the second phase-modifying gas store 25 may be provided. In this way, due to the introduction of the phase modulation gas bank, the work distribution and phase modulation can be separated, so that both work distribution and phase modulation can be satisfied.

Due to various application occasions, various refrigeration capacity and refrigeration temperature, there are not many working conditions that can satisfy both work distribution and phase modulation without a phase-modulating gas storage, so the present invention The application range of the multi-path bypass pulse tube refrigerator can be widened.

Here, if the first compression chamber 51 is connected with the second cold head, the second compression chamber 52 is connected with the first cold head. Same effect. In short, each cold head is connected to a working chamber.

Here, the phase adjuster can also be in other forms, such as selecting a small-hole gas storage type phase adjuster, a two-way inlet type phase adjuster, or a room temperature push piston type phase adjuster, and so on.

Example 2

The coaxial two-stage multi-channel bypass pulse tube refrigerator, as shown in Figure 2, is different from Embodiment 1 in that the cold head adopts a coaxial structure, and its function is the same as that of Embodiment 1, but the structure is more compact.

Example 3

The three-stage multi-channel bypass pulse tube refrigerator structure, as shown in FIG. 3 , consists of a compression mechanism 50 , a cold head 100 and a phase modulator 40 . Cold head 100 is made up of first-stage cold head 10, second-stage cold head 20 and third-stage cold head 30; third-stage cold head 30 is composed of third-stage radiator 32, third-stage first regenerator 331, The third-stage second regenerator 332, the third-stage third regenerator 333, the third-stage cooling heat exchanger 34, and the third-stage pulse tube 31 are connected in sequence; the high-temperature end of the third-stage pulse tube 31 It is connected to the low-temperature end of the second-stage pulse tube 21; the airflow channel between the third-stage first regenerator 331 and the third-stage second regenerator 332 passes through the first-stage cooling heat exchanger 14 but does not It communicates with the first-stage cooling heat exchanger 14 so that the gas flowing through it is cooled; the airflow channel between the third-stage second regenerator 332 and the third-stage third regenerator 333 passes through the second stage The cooling heat exchanger 24 is not in communication with the second-stage cooling heat exchanger 24 so that the gas flowing through it is cooled; Balanced, the heat loss of the third-stage second regenerator 332 is balanced by the second-stage cooling capacity, so that the third-stage cooling capacity heat exchanger 34 can obtain more cooling capacity. The compression mechanism 50 forms the first compression chamber 51, the second compression chamber 52, and the third compression chamber 53 by the stepped piston 54 and the stepped cylinder 55; the third compression chamber 53 is connected with the third stage cold head, and the third compression chamber 53 and the There is a third phase-modulating gas reservoir 35 between the third-stage radiators of the third-stage cold head 30 . Other parts are identical with embodiment 1.

The same principle, although the technical solution of setting three phase-modulating gas storages is provided in this embodiment, according to the content of the invention of the present invention, it can be known that two phase-modulating gas storages in this embodiment can also realize the same function, that is to say Only two of the first phase-modifying gas storage 15 , the second phase-modifying gas storage 25 or the third phase-modifying gas storage 35 may be provided.

Likewise, any compressor working chamber can be connected to any cold head, not limited to the connection method in the figure.

Example 4

The coaxial three-stage multi-channel bypass pulse tube refrigerator, as shown in Figure 4, is different from Embodiment 3 in that the cold head adopts a coaxial structure, and its function is the same as that of Embodiment 3, but the structure is more compact.

Example 5

The two-stage multi-channel bypass pulse tube refrigerator adopting stepped piston recovery work, as shown in Figure 5, compared with Embodiment 1, the difference is that the compression mechanism 50 has a first compression chamber formed by a stepped piston 54 and a stepped cylinder 55 51 , the second compression chamber 52 , and the third compression chamber 53 . The third compression chamber 53 is connected with the inertia tube gas storage 42, so that a part of the expansion work can be recovered to improve the cooling efficiency. Its working principle is that the inertial tube 41 makes the phase difference between the pressure of the inertial tube gas reservoir 42 and the pressure between the first-stage vessel 11 about 180 degrees. In this way, the integral signs of the PVs of the first compression chamber 51 and the second compression chamber 52 and the third compression chamber 53 are opposite, when the first compression chamber 51 and the second compression chamber 52 output work, the third compression chamber 53 inputs work, and also It is to recover a part of the expansion work in the vessel. This works when the inertial tubes are sufficiently phased and there is expansion work to recover.

Example 6

The structure of the two-stage multi-channel bypass pulse tube refrigerator adopting the recovery work of the piston in the back chamber of the motor is shown in Figure 6. Compared with Embodiment 1, the difference is that the stepped piston 54 of the compression mechanism is connected to the drive mechanism 56. , the other end of the drive mechanism 56 is installed with a second piston 58 , a second cylinder 59 is arranged outside the second piston 58 , and a back cavity 57 is formed between the second piston 58 and the second cylinder 59 . The back cavity 57 is connected to the hot end of the first-stage vessel 11 . In an ideal state, the pressure between the first compression chamber 51 and the second compression chamber 52 and the back chamber 57 is the same. In this way, the integral signs of the PVs of the first compression chamber 51 and the second compression chamber 52 and the back chamber 57 are opposite. When the first compression chamber 51 and the second compression chamber 52 output work, the back chamber 57 inputs work, that is, a part of expansion work in the vessel is recovered. This works when the inertial tubes are sufficiently phased and there is expansion work to recover.

In this embodiment, the driving mechanism can be a linear motor.

Example 7

The two-stage multi-channel bypass pulse tube refrigerator using the motor back cavity piston to input work to the inertial tube, as shown in Figure 7, compared with Embodiment 1, the difference is that the stepped piston 54 of the compression mechanism is connected to the drive mechanism 56 , the other end of the drive mechanism 56 is equipped with a second piston 58 , and a second cylinder 59 is arranged outside the second piston 58 , and a back chamber 57 is formed between the second piston 58 and the second cylinder 59 . The inertia tube air storage 42 is connected with the back chamber 57 . Its working principle is that the inertial tube 41 makes the phase difference between the pressure of the inertial tube gas reservoir 42 and the pressure between the first-stage vessel 11 about 180 degrees. In this way, the integral sign of the PV of the first compression chamber 51 and the second compression chamber 52 and the back chamber 57 is the same, when the first compression chamber 51 and the second compression chamber 52 output work, the back chamber 57 also outputs work, that is, to the inertia In the case of insufficient phase modulation of the inertial tubes, the phase modulation capability of the inertial tubes can be enhanced by inputting work to the inertial tubes, thereby improving the cooling effect.

In this embodiment, the driving mechanism can be a linear motor.

Example 8

The two-stage multi-channel bypass pulse tube refrigerator using the motor back chamber to input work to the inertial tube, as shown in Figure 8, compared with Embodiment 1, the difference is that the difference between the stepped piston 54 and the stepped cylinder 55 of the compression mechanism In addition to forming the first compression chamber 51 and the second compression chamber 52 , a back chamber 57 opposite to the first compression chamber 51 and the second compression chamber 52 is also formed.

The inertia tube air storage 42 is connected with the back chamber 57 . Its working principle is the same as that of Embodiment 7, but because the volume of the stepped cylinder cavity and the diameter of the stepped piston of the driving structure are restricted by other conditions, they cannot be adjusted arbitrarily. Generally, the motor is installed in the back chamber 57, and the volume cannot have too much freedom of adjustment. Therefore, the degree of freedom of work input to the inertial tube cannot be the same as that in Embodiment 7.

Example 9

Generally, in order to improve the service life, a gap seal is used between the stepped piston 54 and the stepped cylinder 55 . The length of the gap seal between the stepped piston 54 and the stepped cylinder 55 will change with the position of the stepped piston 54, so the leakage between the first compression chamber 51 and the second compression chamber 52 is not only related to the flow resistance of the regenerator, but also to the step The position of the piston 54 is related, which will cause a direct current component to exist between the first compression chamber 51 and the second compression chamber 52 , thereby generating a direct current component between the first-stage cold head 10 and the second-stage cold head 20 . The DC component is a fundamental phenomenon of a pulse tube refrigerator with a loop, such as a two-way intake pulse tube refrigerator. If it is not suppressed, the efficiency of the refrigerator will be reduced or the temperature will be unstable.

In order to overcome this difficulty, as shown in FIG. 9 , in this embodiment, a piston ring groove 541 is provided at the lower part of the stepped piston 54 , so that the length of the gap seal 5455 can be controlled. If the length of the piston ring groove 541 is very long and the sealing length does not change during the maximum stroke, then it is a fixed-length seal.

Example 10

Based on the description of Embodiment 9, in order to further control the length of the gap seal to control the direct current component, this embodiment has provided a piston ring groove 541 on the lower part of the stepped piston 54 in Embodiment 9, and further set a short cylinder on the stepped cylinder 55. The ring groove 551 is shown in FIG. 10 .

Example 11

As shown in FIG. 11 , the difference from Embodiment 9 is that the stepped cylinder 55 of this embodiment is provided with a cylinder long annular groove 552 , and the length of the gap seal 5455 remains unchanged when the stepped piston 54 is at its maximum stroke.

Example 12

As shown in Figure 12, the structure of the stepped piston and the stepped cylinder of this embodiment is adapted to the three-stage multi-path bypass pulse tube refrigerator described in Embodiment 3. In this embodiment, two A piston ring groove 541, so that the length of the gap seal 5455 can be controlled.

Certainly, the stepped piston and the stepped cylinder of this embodiment may also adopt the structure shown in FIG. 10 or FIG. 11 .

Words such as "first", "second" and "third" are used herein to define components, and those skilled in the art should know that the use of words such as "first", "second" and "third" is only Components are distinguished for convenience of description. Unless otherwise stated, the above terms have no special meanings.

The above descriptions of the embodiments are for those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative effort. Therefore, the present invention is not limited to the above-mentioned embodiments. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (10)

1. A multi-path bypass pulse tube refrigerator, comprising a cold head, a compression mechanism and a phase modulator, wherein the cold head is provided with n stages altogether, and each stage of cold head is composed of a radiator, a regenerator, and a cooling capacity for heat exchange The compression mechanism has n compression chambers, and each compression chamber is connected to each cold head respectively. The high temperature end of the blood vessel of the nth cold head is connected to the n-1th The low-temperature end of the pulse tube of the first-stage cold head is connected, and the high-temperature end of the first-stage pulse tube is connected with the phase modulator. It is characterized in that a phase modulation device is provided between at least n-1 level cold head and the corresponding compression chamber. Gas storage, n≥2, and it is a positive integer. 2. A multi-path bypass pulse tube refrigerator according to claim 1, characterized in that the phase-modulating gas storage is a dead volume between the cold head and the compression chamber, or a connecting pipe therebetween. 3. A multi-channel bypass pulse tube refrigerator according to claim 1, characterized in that, the phase modulator is composed of an inertial tube and an inertial tube gas store connected in sequence, and the pulse tube of the first stage cold head The tube is connected with the inertia tube. 4. A multi-path bypass pulse tube refrigerator according to claim 1, characterized in that, the phase modulator is selected from a small hole gas storage type phase modulator, a two-way inlet type phase modulator or a room temperature shifting Piston type phaser. 5. A multi-path bypass pulse tube refrigerator according to claim 1, characterized in that, In the compression mechanism, a compression chamber is formed by a stepped piston and a stepped cylinder, and a piston ring groove is arranged at the lower part of the stepped piston, so that the gap sealing length between the stepped piston and the stepped cylinder is controllable; or, In the compression mechanism, a compression chamber is formed by a stepped piston and a stepped cylinder, and a cylinder ring groove is provided on the stepped cylinder, so that the gap sealing length between the stepped piston and the stepped cylinder is controllable; or, In the compression mechanism, a compression chamber is formed by a stepped piston and a stepped cylinder. A piston ring groove is provided at the lower part of the stepped piston, and at the same time, a cylinder ring groove is provided on the stepped cylinder, so that the gap between the stepped piston and the stepped cylinder is sealed. Controllable length. 6 . The multi-path pulse tube refrigerator according to claim 3 , wherein the inertia tube gas reservoir is connected to one of the compression chambers to recover part of the expansion work. 7 . 7. A multi-path bypass pulse tube refrigerator according to claim 1, characterized in that, in addition to having n compression chambers, the compression mechanism is also provided with a back chamber opposite to the compression chamber, each The hot end of the vessel after the first-stage cold head is connected to the back cavity is connected to recover part of the expansion work. 8. A multi-path bypass pulse tube refrigerator according to claim 3, characterized in that, in addition to having n compression chambers, the compression mechanism is also provided with a back chamber opposite to the compression chamber, so The inertial tube gas storage mentioned above is connected with the back cavity of the compression mechanism. 9. A multi-path bypass pulse tube refrigerator according to claim 1, characterized in that, n=2, specifically a two-stage multi-path bypass pulse tube refrigerator, The cold head is composed of the first-stage cold head and the second-stage cold head. The second-stage cold head is composed of the second-stage radiator, the second-stage first regenerator, the second-stage second regenerator, the second-stage cooling heat exchanger, and the second-stage pulse tube. made of secondary connections; The high-temperature end of the second-stage vessel is connected to the low-temperature end of the first-stage vessel; The airflow channel between the second-stage first regenerator and the second-stage second regenerator is cooled by the first-stage cooling heat exchanger; The inertial tube is connected to the high-temperature end of the first-stage pulse tube; The compression mechanism consists of a stepped piston and a stepped cylinder to form a first compression chamber and a second compression chamber; the first compression chamber is connected to the first-stage radiator of the first-stage cold head, There is a first phase-adjusting air reservoir between the first-stage radiators; the second compression chamber is connected to the second-stage radiator of the second-stage cold head, and between the second compression chamber and the second-stage radiator of the second-stage cold head There is a second phase-adjusting gas storage in between. 10. A multi-path bypass pulse tube refrigerator according to claim 1, characterized in that, n=3, specifically a three-stage multi-path bypass pulse tube refrigerator, The cold head is composed of the first-level cold head, the second-level cold head and the third-level cold head. The first-stage pulse tubes are connected in sequence, and the second-stage cold head is composed of the second-stage radiator, the second-stage first regenerator, the second-stage second regenerator, the second-stage cooling heat exchanger, The second-stage pulse tubes are connected in sequence, and the third-stage cold head is composed of a third-stage radiator, a third-stage first regenerator, a third-stage second regenerator, a third-stage third regenerator, The third-stage cooling heat exchanger and the third-stage pulse tube are connected in sequence; The high-temperature end of the third-stage vessel is connected to the low-temperature end of the second-stage vessel, and the high-temperature end of the second-stage vessel is connected to the low-temperature end of the first-stage vessel; The air flow channel between the third-stage first regenerator and the third-stage second regenerator is cooled by the first-stage cold heat exchanger, and the third-stage second regenerator and the third-stage third regenerator The airflow channel between the two is cooled by the second-stage cooling heat exchanger, and the airflow channel between the second-stage first regenerator and the second-stage second regenerator is cooled by the first-stage cold heat exchanger; The inertial tube is connected to the high-temperature end of the first-stage pulse tube; The compression mechanism consists of a stepped piston and a stepped cylinder to form a first compression chamber, a second compression chamber, and a third compression chamber. The first compression chamber is connected to the first-stage radiator of the first-stage cold head. There is a first phase-adjusting gas reservoir between the first-stage radiators of the first-stage cold head; the second compression chamber is connected to the second-stage radiator of the second-stage cold head, and the There is a second phase-modulation air reservoir between the secondary radiators, the third compression chamber is connected to the third-stage cold head, and there is a third phase modulation between the third compression chamber and the third-stage radiator of the third-stage cold head gas storage.