JPH0735935B2 - Chiller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a gas cooler used for cooling an infrared element, an air liquefier, etc., such as a Stirling cooler.

[Prior Art] FIG. 3 is a cross-sectional side view showing a schematic configuration of a conventional Stirling type gas cooler disclosed in, for example, Japanese Patent Publication No. 54-28980. In the figure, reference numeral 1 denotes a cylinder, and a piston 2 reciprocates inside the cylinder 1. A cold finger 3 contains a displacer 4 which reciprocates according to the pressure fluctuation of the working gas, and a lower part thereof communicates with the cylinder 1 by a communication pipe 5. The upper working surface 4b of the displacer 4 delimits the expansion space 6, which is the first working space 7 between the lower working surface 4a of the displacer 4 and the communication pipe 5, the upper working space of the piston 2. A second space 8 between the surface 2a and the communication pipe 5,
A working space is formed with the heat storage 9 provided in the displacer 4, the space in the communication pipe 5, and the like. The regenerator 9 can communicate with the working gas below it via the central hole 10 and also with the working gas above via the central hole 11 and the radial flow duct 12. The machine also includes a freezer 13 as a heat exchanger for exchanging heat between the expanded cold working gas and the object to be cooled.

A seal 14 is arranged between the piston 2 and the wall of the cylinder 1 to prevent the flow of working gas between the buffer space 15 below the piston 2 and the working space.

A seal 16 is provided between the displacer 4 and the cold finger 3 to force the flow of the working gas between the expansion space 6 and the first compression space 7 to flow in the heat accumulator 9.

A lightweight sleeve made of a non-magnetic and non-magnetizable material such as aluminum in the piston 2 and the buffer space 15 below the piston 2.
Equipped with 17. Wrap a conductor around the sleeve 17 and coil
Forming a coil 18, which coil 18 is connected to leads 19, 20 which pass through the wall of the cylinder 1, these leads 19, 20 being connected to electrical terminals 21, 22 respectively outside the cylinder 1. The coil 18 can reciprocate in the annular gap 23 in the axial direction of the piston 2, and the armature magnetic field exists in the annular gap 23. The lines of force of this armature magnetic field extend in a radial direction transverse to the moving direction of the coil 18. In this case, the permanent magnetic field is obtained using an annular permanent magnet 24 having upper and lower magnetic poles, a soft iron annular disc 25, a soft iron cylinder 26 and a soft iron circular disc 27. The annular permanent magnet 24, the soft iron annular disk 25, the soft iron cylinder 26, and the soft iron circular disk 27 form a closed magnetic circuit, that is, a closed magnetic force line circuit. The sleeve 17, coil 18, and lead wires 19, 2 described above
0, annular spacing 23, annular permanent magnet 24, soft iron annular disc 2
5, the soft iron cylinder 26 and the soft iron circular disk 27 constitute a linear motor 28 for driving the piston as a whole. Further, the piston 2 and the displacer 4 are reciprocally engaged in the cylinder 1 and the cold finger 3 via the elastic member 29 for the piston and the elastic member 30 for the displacer, respectively, and the piston 2 and the displacer 4 are fixed at a stationary position. And the neutral position during operation is defined.

Next, the operation of the conventional Stirling type gas cooler will be described. When an AC power source (not shown) having a resonance frequency of the system is connected to the electric terminals 21 and 22, the coil 18 is affected by the permanent magnetic field in the radial direction of the annular gap 23, and the coil 18 receives a periodic Lorentz force in the axial direction. As a result, the system including the piston 2, the sleeve 17, and the coil 18 and the elastic member 29 for the piston is in a resonance state, and the assembly vibrates in the axial direction. The vibration of the piston 2 causes the expansion space 6, the first compression space 7, the second compression space 8, the communication pipe 5,
Heat storage device 9, central hole 10, central hole 11, radial duct 12
The working gas enclosed in the working space consisting of the freezer 13 and the freezer 13 causes a periodical pressure change, and a periodical alternating vibrational force is generated in the displacer 4 by the flow rate change of the gas passing through the heat storage device 9. . In this way, the displacer 4 including the heat accumulator 9 reciprocates axially in the cold finger 33 at the same frequency as the piston 2 but at different phases.

When the piston 2 and the displacer 4 move while maintaining an appropriate phase difference, the working gas enclosed in the working space constitutes a thermodynamic cycle known as the "reverse Stirling cycle", mainly the expansion space 6 and the freezer. Generates cold heat to 13. With the "reverse Stirling cycle",
For the principle of cold heat generation, refer to the document "Cryo coolers".
(G. Walker, Plenum Press, New york, 1983, PP. 177-12
It is explained in detail in 3). The principle will be briefly described below.

The gas compressed in the second compression space 8 by the piston 2 has its compression heat cooled while flowing through the communication pipe 5, and flows into the first compression space 7, the central hole 10, and the heat storage device 9. In the heat storage unit 9, the working gas is pre-cooled by the cold heat stored before the half cycle, and the working gas further enters the expansion space 6 through the central hole 11, the radial circulation duct 12 and the freezer 13. Then, when most of the working gas enters the expansion space 6, expansion starts and cold heat is generated in the expansion space 6. The working gas then returns to the flow path while releasing cold heat to the heat storage device 9 in the reverse order and enters the second compression space 8. At this time, heat is taken from the outside in the freezer 13 to cool the outside. Then, when most of the working gas returns to the second compression space 8, the compression starts again and the next cycle starts. By the above process, the "reverse Stirling cycle" is completed and cold heat is generated.

[Problems to be Solved by the Invention] In the above conventional technique, it is necessary to determine the stroke phase of the displacer so as to maximize the cooling capacity in relation to the pressure change in the expansion space. However, since the conventional coolant has frictional resistance between the displacer and the inner surface of the cold finger, and there is a flow loss of the working gas in the heat accumulator, these two factors have a great influence on the stroke phase of the displacer. Further, it is very difficult to accurately determine these two factors, and there is a problem that the cooling capacity itself of the cooler is not stable.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a cooler that can maximize the cooling capacity without directly considering the stroke and phase of the displacer.

[Means for Solving the Problems] A cooler according to the present invention includes a closed magnetic circuit including an exciting coil and an exciting yoke that fix a conductive ring coaxially with a displacer and generate a magnetic flux interlinking with the conductive ring. It is provided with a power supply for supplying a direct current to the exciting coil, and the magnitude of the direct current can be controlled.

[Operation] With the vibration of the displacer, an eddy current is generated in the conductive ring fixed to the displacer. Due to the generation of this eddy current, a resistance force is generated against the vibration, and the electromagnetic damper functions. Since the magnitude of the DC current can be controlled to any magnitude, the damper action can be adjusted arbitrarily. Therefore, if the magnitude of this DC current is controlled so that the cooling capacity of the cooler is maximized,
This means that the above problems can be solved.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 31 is an exciting coil, and 32 is a cylindrical soft iron yoke arranged to focus a magnetic field by a direct current supplied to the exciting coil 31. A pole piece 33 made of soft iron is arranged at the center of the soft iron yoke 32. 34 is a displacer 4
Has a cylindrical shape that is adhered to a conductive material (for example,
It is a conductive ring made of copper, aluminum, etc.). The conductive ring 34 is inserted in a magnetic gap formed between the soft iron yoke 32 and the ball piece 33 in a non-contact state. With this structure, the conductive ring is moved along with the reciprocating motion of the displacer 4.
Since 34 moves so as to interlink the magnetic flux in the magnetic gap formed by the exciting coil 31, an eddy current based on an electromagnetic flux induction action is generated in the conductive ring 34 made of a conductive material, Eddy current loss occurs. This eddy current loss is proportional to the movement speed of the displacer 4, and an electromagnetic force is generated in response to this movement. Therefore, it acts as a damping action for the movement of the displacer 4. Then, as shown in FIG. 2, when the magnitude of the DC current supplied from the DC power source 36 connected to the exciting coil 31 is arbitrarily changed, the magnetomotive force of the exciting coil changes, and the magnetic flux density of the magnetic gap is almost proportional to it. Will also change. Therefore, the magnitude of the eddy current generated in the conductive ring 34 also changes in proportion, so that the damping action acting on the displacer 4 can be controlled.

With the above configuration, without considering the pressure loss of the working gas in the heat storage device 9 and the friction loss acting on the displacer,
By adjusting only the magnitude of the direct current supplied to the exciting coil 31, the stroke and movement phase of the piston can be adjusted.

As described above, according to the present invention, the stroke and phase of the displacer are directly controlled by controlling the magnitude of the direct current to the exciting coil while observing the cooling capacity of the cooler. The cooling capacity of the chiller can be maximized without consideration. Therefore, the cooling capacity of the cooler can be improved and stable performance can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a cooler according to an embodiment of the present invention, FIG. 2 is a block diagram showing coupling between an exciting coil and a DC power source in FIG. 1, and FIG. 3 is a conventional cooler. It is sectional drawing shown. 1 ... Cylinder, 2 ... Piston, 2a, 4a, 4b ... Working surface, 3 ... Cold finger, 4 ... Displacer,
5 ... communication pipe, 6 ... expansion space, 7 ... first compression space,
8: second compression space, 9: heat storage device, 10: central hole, 11
…… Center hole, 12 …… Radial flow duct, 13 …… Freezer, 14 …… Seal, 15 …… Buffer space, 16 …… Seal, 17 …… Sleeve, 18 …… Coil, 19,20 …… Lead Wires, 21,22 ... Electronic terminals, 23 ... Ring gap, 24 ... Ring permanent magnet, 25 ... Soft iron ring disk, 26 ... Soft iron cylinder, 27 ... Soft iron circular disk, 28 ... Linear motor, 29
...... Plastic elastic member, 30 …… Displacer elastic member. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A coil provided in a magnetic field produced by a permanent magnet, and an alternating current is caused to flow through the coil to vibrate a piston connected to the coil, a cylinder on which the piston slides, and a cold communicating with the cylinder. By causing a periodic pressure change in the working gas enclosed in the fingers, the displacer contained in the cold fingers is caused to vibrate and at the same time the working gas is compressed and expanded in the cylinder and the cold fingers to cause the cold fingers to move. In a cooler that generates cold heat, a conductive ring is fixed coaxially with the displacer, and a closed magnetic circuit composed of an exciting coil and an exciting yoke that generates a magnetic flux interlinking with the conductive ring is disposed, and the exciting coil is connected to the exciting coil. It is equipped with a power supply that supplies a direct current of Adjustable stroke and the phase of the serial displacer and the cooler.