JPS61265457A - Refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a refrigerating machine, and in particular a reciprocating drive of a movable body such as a split Stirling cold storage refrigerator by differential pressure across the movable body. Regarding refrigerators such as

[Conventional technology]

A known split Stirling refrigerator is shown in Figure 3 (I).
~(ff). This refrigerator includes a reciprocating compressor (14) and a cold finger section (IB). The piston (17) of the comb 1/tsusa (14) pressurizes a refrigerant gas such as helium and causes a curved pressure fluctuation with a sine force. Said pressure fluctuations in the head chamber (8) are transmitted into said cold finger part (18) through a supply pipe (20).

Split Stirling refrigerators typically have a compressor driven by an electric motor. A variant of this type of refrigerator is the Split Vufll type.
eumier) refrigerator. This device uses a thermally driven compressor.

Inside the housing of the cold finger section (1B), a cylindrical moving body freely reciprocates to change the volume of the greenhouse chamber (22) and cold section (24) within the cold finger section (18). It is being done. The moving body (2s) includes a regenerative heat exchanger (28). The regenerative heat exchanger (28)
is formed by stacking hundreds of thin mesh side metal screen disks to form a cylindrical matrix. Other types of heat exchangers are also known, such as stacked poles. Helium is passed through the heat exchanger (28) between the hot room (22) and the cold room (20).
) is allowed to flow freely through the As discussed below, the piston member (30) is located at the end of the cold finger section (16) in the gas spring chamber (3).
2) a movable body (26) extending upward from the main body portion;

The refrigerator shown in FIGS. 3(I)-(IT) is shown as containing two separate chambers of pressurized gas. The working volume of the gas that forms the working chamber of the gas is the compressor (
14), the gas in the supply pipe (20), and the gas in the hot chamber (22) and the cold chamber (2).
4) and the gas in the heat exchanger (28) of the cold finger section (18). It is the gas spring chamber (32) that forms the second gas working volume;
The spring chamber (32) is sealed to the working chamber by a piston seal (34) surrounding the drive piston member (30).

Next, the operation of this known tin-lit Stirling type refrigerator will be explained. At the time of the cycle shown in FIG. 3(I), the moving body (26) is
6) at the end of the cold chamber in the compressor (14).
) is compressing the gas in the working chamber. compressor(
The compressive movement of the piston (17) of 14) increases the pressure in the working chamber from the lowest pressure to the highest pressure, and this warms the gas in the working chamber. Spring room (3
2) The pressure within is stabilized at a level between the lowest and highest pressure levels within the working chamber. Thus,
At some point, the increasing pressure in said working chamber creates a differential pressure against the drive piston member (30) sufficient to overcome the frictional resistance of the moving object seal (38) and the piston member seal (32). generate. The piston member (aO) and the movable body (28) then rapidly rise to the position shown in FIG. Due to the movement of the moving body (26), the gas in the high pressure working chamber at almost ambient temperature is transferred to the heat exchanger (28).
) and is forcibly guided into the cold room (24). The heat exchanger (28) absorbs the heat of the pressurized gas passing through it, thereby reducing the temperature.

Due to the sine curve drive by the crankshaft device, the compressor piston (17) is now in the third position.
The volume of the working chamber begins to expand as shown in figure (m). Due to this expansion, the high pressure helium gas in the cold chamber (24) is further cooled. Over the entire length of the heat exchanger (2 days)
It is this cooling in the cold chamber (24) that generates a refrigeration effect that maintains a temperature gradient of more than 200°. At some point in the expansion movement of the piston (17),
The pressure in the working chamber drops below the pressure in the spring chamber (32) and the differential pressure acts on the piston member (30) sufficiently to overcome the frictional force of the seal. Then, the moving body (28) is driven downward to the position shown in Fig. 3 (17). The position shown in Fig. 3 (rV) is the position before reaching the position shown in Fig. 3 (1). It is also the starting position.

The cooled gas in the cold room (24) is transferred there to a heat exchanger (
28) is forced to pass through a heat exchanger to extract heat from the heat exchanger.

It is known that the phase relationship between the pressure in the working chamber and the movement of the moving body is determined by the braking force of the seal applied to the moving body. For example, if these seals have a very low frictional resistance, the moving body moves from the lower position shown in FIG. 3(I) to the upper position shown in FIG. 3(n) in the working chamber. The pressure in the spring chamber (32) is brought to a pressure approximately intermediate between the minimum and maximum values of the working chamber pressure, which will shift when the pressure increases above the pressure in the spring chamber (32). Therefore, the movement of the moving body will already take place by the time the piston (17) of the compressor reaches the middle of its stroke, which means that a considerable amount of gas in the cold chamber (24) of the cold finger will be removed. This would have undesirable consequences, since compressing the gas would therefore warm the gas.

In order to increase the efficiency of the device, the upward movement of the moving body is such that the compressor piston (L7) is near the end of its stroke as shown in FIGS. 3(I) and 3(n). will be delayed until In this way, almost all the gas is compressed and warmed in the cold finger greenhouse chamber (22). The warmed gas is then simply moved through the heat exchanger (28) the next time the mobile moves upwards.

Thus, the gas currently contained in the cold chamber (24) has been cooled as much as possible before it is further cooled by expansion. Similarly, within the cold chamber of the cold finger section, it is preferred that the gas is expanded as much as possible before being transferred to the greenhouse chamber by the moving body (28); in other words, the movement of the moving body is must be delayed for pressure changes at .

In conventional devices, the seal (34) and the seal (38
) were precisely designed and manufactured to apply a predetermined amount of load to the moving object, and thus slow the movement of the moving object by an optimal amount. A major problem with split-stirling refrigerators is that the braking action of these seals changes as the seals wear.

Next, this problem will be clarified according to Figure 4.

In the figure, the horizontal axis is the crank angle of the piston (17),
The vertical axis indicates the displacement of the piston (17) and the displacement of the moving body (28) with respect to the crank angle. Piston (17)
Since the displacement is not shown or is driven by a zinc mechanism, the displacement is approximately sinusoidal. By the way,
Crank angle θ; O is the bottom dead center of the piston, and θ=π is the top dead center.

Here, a load force (frictional force) is applied in advance to the moving body by the seal (34) and the seal (3B). The displacement is determined by this load force and the pressure conditions in the spring chamber (32) and greenhouse chamber (22).The solid line in the diagram is for the piston (!7) where the split Stirling refrigerator exhibits the highest performance. This shows ideal displacement. Here, the displacement of the moving body when the load force (frictional force), that is, the braking force applied in advance to the moving body by the seal (34) and the seal (36) changes, will be explained. When the load decreases, the displacement occurs as shown by the dashed line. If the load increases too much, the displacement will occur as shown by the broken line. As the load changes in this manner, the displacement deviates from the ideal displacement, resulting in a decrease in the performance of the refrigerator.

[Problem that the invention seeks to solve]

However, in the conventional refrigerator, large vibrations occur in the cold finger section (18) due to the reciprocating inertia mass of the moving body (28) reciprocating within the cold finger section (1B), and this vibration is caused by the cold finger section (18) This was an important flaw depending on the purpose for which it was used.

The object of the present invention is to provide a refrigerator that can prevent the above-mentioned problems, particularly vibrations in the cold finger section (1G).

[Means for solving problems]

A refrigerator according to the present invention includes a disk-shaped permanent magnet provided at the lower part of a piston member of a movable body protruding into a spring chamber in a housing, and a disk-shaped permanent magnet installed at a position facing the disk-shaped permanent magnet from the outside of the spring chamber and approaching the disk-shaped permanent magnet. a magnetoresistive sensor that senses the vibration, a forced vibration electromagnet fixed to the housing, a vibration sensor that detects vibration of the cold finger, and operating the forced vibration electromagnet based on a detection output of the vibration sensor. A vibration control circuit is provided to cancel the reciprocating inertia force generated by the reciprocating motion of the moving body, thereby preventing vibration of the cold finger.

[Effect]

In this invention, a balance body having an equivalent mass equivalent to that of the cold finger is connected to the reciprocating motion of the moving body in the axial direction by approximately 1Bθ°.
Since the cold finger is forced to reciprocate in directions with different phases, it becomes possible for the cold finger to approximately balance the entire reciprocating mass, and as a result, the signal decreases.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings. In FIG. 1, the same reference numerals as in FIGS. 3 to 6 indicate the same functional configurations. (101) is a cold finger (
(102) is a disc-shaped permanent magnet attached to the lower part of the piston member of the movable body (26), and (103) is magnetized by the proximity of the magnet. A magnetoresistive sensor whose resistance changes to perform switching, (102) is the output line of the magnetoresistive sensor, and (103a) and (103b) are input lines of the DC voltage applied to the magnetoresistive sensor.

In addition, (104) has a central magnetic pole (10
(105) is a disk-shaped electromagnet with a magnetic pole in the axial direction, which is provided opposite to the central magnetic pole of the electromagnet. It is a permanent magnet. (108), (107) connect the permanent magnet (105) to the electromagnet (104) c7) center magnetic pole (
104a) is a coil spring provided with a predetermined spacing, and the spacing is equal to or longer than the stroke of the moving body (26). (108) is the permanent magnet (10
5) A guide member for supporting the reciprocating motion, and is made of a polyimide-based or Teflon-based self-lubricating material. (10
9) is a vibration sensor for detecting vibration in the moving axis direction of the moving body (26) below the electromagnet (104).

Further, FIG. 2 is a block diagram showing a vibration control circuit related to the method of driving the electromagnet (104) shown in FIG. 1.

In the figure, (110) is the output (
102) into an 0N-OFF pulse, the mobile object (2
6) A switching circuit that turns on at bottom dead center, (1
11) is an electromagnet (10) based on the switching signal.
4) applying a voltage to push up the permanent magnet (105) toward the moving body (2B) when the switching signal is ON, and calculating the period of the switching signal;
An electromagnet drive circuit that pulls the permanent magnet (105) toward the electromagnet (104) after the expansion period immediately after the switching signal is turned ON; (113) indicates the winding of the electromagnet (104). (114) indicates a vibration sensor that detects the magnitude of vibration of the cold finger (16) and outputs the magnitude. The switching circuit (115) determines whether or not the output is a signal commensurate with a predetermined magnitude of vibration, and if the output is not within the permissible range, the switching circuit (110
), a vibration level determination circuit that outputs a phase correction signal to (
11B) is a switching circuit (110) that connects the mobile body (16
) is a phase correction circuit for correcting the lead angle of the ON signal generated when the motor is at the bottom dead center. With the vibration control circuit configured in this way, when the compressor (14) operates at a predetermined rotational speed or reciprocating speed, the movable body (2
6) also has a reciprocating speed equivalent to that of a compressor. Therefore, the average magnitude of the reciprocating inertia of the moving body (2B) determined by the mass of the moving body (2B) and its reciprocating speed is approximately constant during operation, and as a result, the mass of the permanent magnet also varies depending on the reciprocating stroke of the permanent magnet. In this embodiment, the mass of the permanent magnet and its reciprocating stroke are determined so that the average values of the reciprocating inertia forces of the moving body and the permanent magnet are approximately equal.

Therefore, in this embodiment, when the compressor is driven by a motor (not shown), the movable body (2θ) moves back and forth as explained in the conventional embodiment, and the tip of the cold finger (18) is heated to about -200°C. become. On the other hand, by sensing the reciprocating motion of the moving body, the permanent magnet (105) is forcibly excited by the electromagnet (104) in the direction opposite to the reciprocating motion of the movable body (26). At this time, the vibration control circuit operates in the cold finger (16) main body so that the reciprocating inertia forces of the two cancel each other out, so the vibration becomes extremely small. In addition, in this example, an electromagnet (104
), the permanent magnet (105) was forcibly excited, but instead of the permanent magnet, a voice coil type, that is, a movable winding was used, and a weight of an appropriate mass was attached to the movable winding to forcibly excite it. Needless to say, it is possible to obtain a refrigerator having a structure similar to that of the practical system shown in FIGS. 1 and 2.

〔Effect of the invention〕

As described above, according to the present invention, the magnitude of the average value of the reciprocating inertia force of the reciprocating motion of the moving body is made equal to the magnitude of the average value of the reciprocating inertia force of the permanent magnet forcibly excited by the electromagnet. Since the permanent magnets are moved so that they cancel each other out, and the phase of the reciprocating motion of the permanent magnets is controlled so that the vibration level of the vibration sensor is reduced, the vibration of the cold finger can be reduced. As a result, a refrigerator with low vibration can be provided.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing an embodiment of the present invention, Fig. 2 is a block diagram showing the mechanical configuration of the vibration control circuit, and Fig. 3
(1) to (■) are explanatory diagrams showing the action of the cold finger of the refrigerator. In the figure, (2B) is a moving body, (102) is a disk-shaped permanent magnet, (103) is a magnetoresistive sensor, (104) is an electromagnet, (105) is a disk-shaped permanent magnet, and (109) is a vibration sensor. , (108) is a guide member, (ito) is a switching circuit, (111) is an electromagnet drive circuit, (113) is an electromagnet, (114) is a vibration sensor, (115) is a vibration level determination circuit, and (116) is a phase. This is a correction circuit. Agent Masuo Oiwa Figure 1

Claims (4)

[Claims] (1) A compressor, a cold finger housing communicated with the compressor through a supply pipe, a movable body configured to reciprocate within the housing, gas in contact with opposing end surfaces of the movable body, and the moving body a gas working chamber and a gas spring chamber separated by a fluid seal surrounding the moving body, the moving body being driven by a differential pressure between the working chamber and the spring chamber; In a refrigerator that has a phase relationship between the pressure and the motion of the movable body determined by a braking force applied to the movable body, the movable body protrudes into the spring chamber in the housing. A disk-shaped permanent magnet provided at the bottom of the piston member, a magnetic resistance sensor installed at a position facing the disk-shaped permanent magnet from the outside of the spring room and detecting its approach, and a forced vibration electromagnet fixed to the housing. a vibration sensor that detects the vibration of the cold finger; and a vibration that cancels the reciprocating inertia force generated by the reciprocating motion of the moving body by operating the forcibly vibrating electromagnet based on the detection output of the vibration sensor. A refrigerator characterized by comprising a control circuit. (2) The forcibly vibrating electromagnet includes an electromagnet whose magnetic poles are configured to surround a central magnetic pole, and a circular flat permanent magnet arranged opposite to the central magnetic pole, and the permanent magnet is inserted from both sides of the holder and the electromagnet. A patent characterized in that the moving body is held at a distance of 1/2 or more of the stroke of the moving body from the central magnetic pole, and is equipped with a self-lubricating guide material to guide the reciprocating movement of the permanent magnet from the surrounding magnetic poles of the electromagnet. Claim 1
Refrigerator as described in section. (3) The stroke of the permanent magnet is adjusted such that the average value of the inertial force accompanying the reciprocating motion of the moving body and the average value of the inertial force accompanying the reciprocating motion of the permanent magnet are approximately the same. The refrigerator according to claim 1 or 2, wherein the mass is determined. (4) The vibration control circuit includes a position detecting means comprising a disk-shaped permanent magnet attached to the lower part of the piston member of the moving body and a magnetic resistance sensor, a switching circuit that performs switching response based on the detection output of the magnetic resistance sensor; a vibration level determination circuit that outputs a phase correction signal to the switching circuit when the vibration exceeds a predetermined value; a phase correction circuit that performs advance angle correction based on the ON signal of the switching circuit; A refrigerator according to any one of claims 1 to 3, characterized in that the refrigerator comprises an electromagnet drive circuit that forcibly vibrates a permanent magnet.