JPH02146470A - Stirling refrigerator - Google Patents

Abstract

PURPOSE:To certainly prevent the working gas from leaking without complicating the construction by a method wherein a brushless type motor is employed, its rotor is housed in a crank case or in a displacement part connecting to the crank case, and its winding is arranged outside the crank case. CONSTITUTION:A motor 2 is of a brushless type, its rotor 21 is housed in a crank case 1, and its winding 22 is arranged outside the crank case 1. The rotor 21 is connected to a crank shaft 109 directly or through a speed reducer. The rotor 21 is housed inside the crank case 1 and connected to the crank shaft 109 without a dynamic seal. The winding 22 is placed outside the crank case 1 and directly cooled by the outside air sent by a thin type fan 27.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a Stirling refrigerator that is suitably used to generate extremely low temperatures.

[Prior Art] A Stirling refrigerator generally uses He as a working gas and uses its adiabatic expansion to obtain extremely low temperatures. The schematic configuration and principle will be explained based on Fig. 5.
A piston 102, a displacer 103, and a crankshaft 109 for orthogonally distributing power to these are housed in a crankcase 101 indicated by a thick line in the figure.

A compression chamber 104 is formed between the working end of the piston 102 and the crankcase 101, and an expansion chamber 105 is formed between the working end of the dispressor 103 and the crankcase 101. Further, the compression chamber 104 and the expansion chamber 105 are connected to each other by a gas transfer line 10 with a regenerator 106 interposed therebetween.
Connected by 7. And these compression chambers 104
, He gas is sealed in a space sealed by the expansion chamber 105 and the gas transfer line 107, and it is transferred to the piston 10.
After being compressed in step 2, it is fed into the expansion chamber 105 and adiabatically expanded in the displacer 103, and after swelling, it is sent back to the compression chamber 104 and subjected to compression again.

By operating such a well-known Stirling cycle, an extremely low temperature cold head 108 is generated at the casing end forming the expansion chamber 105.

Note that the machine chamber 110 in which the crankshaft 109 is housed and the compression chamber 104 and expansion chamber 105 described above are separated by seals 111 and 112, and He
This is to prevent gas leaks. However, these seals 111 and 112 must have low sliding resistance and must be oil-free so that the oil does not enter the low-temperature part and solidify due to the working gas flow, so they are too expensive. It is difficult to improve the sealing effect. In particular, in the expansion chamber 104, leakage is likely to occur through the seal 111 when the gas pressure temporarily increases. For this reason, in the past, the entire crankcase 101 was made airtight, and the machine chamber 110 was also filled with He gas.
4 and the expansion chamber 105, and also to ensure that some of the leaked He gas is refluxed to prevent a decrease in the refrigerating capacity due to leakage.

[Problems to be Solved by the Invention] However, even if such a configuration is adopted, the conventional crankcase 101 does not have perfect airtightness, so the filled He gas escapes slowly and the effect is halved. That is, as shown in the figure, in a typical Stirling refrigerator, an existing motor 113 is separately attached to the outside, and this motor 113 passes through the crankcase 101 and is connected to the internal crankshaft 109. . For this reason, it is necessary to provide a dynamic seal as a shaft seal in the penetrating portion 101a of the crankcase 101, and there is no way to prevent leakage from occurring from this dynamic seal beyond a certain level.

On the other hand, in order to solve this problem, a crankcase 121 has been considered that houses the entire motor 113 and eliminates the need for a dynamic seal, as shown in FIG. However, in this case, although the crankcase 121 is completely sealed, the heat generated from the windings within the motor 113 must be removed to the outside of the crankcase 113. For this reason, it is necessary to perform processing such as providing a cooling water pipe 114 for introducing cooling water into the motor 113 and connecting the winding part with the outside using a material with good heat conductivity (not shown). This results in the disadvantage that the motor structure becomes complicated.

The present invention was made in view of these problems, and aims to realize a Stirling refrigerator that can reliably prevent leakage of working gas without complicating the structure. There is.

[Means for Solving the Problems] In order to achieve the above object, the present invention employs the following configuration.

That is, in the Stirling refrigerator of the present invention, at least a piston, a displacer, and a crankshaft are housed in a crankcase filled with working gas, and the piston and the displacer are driven synchronously by a common motor via the crankshaft. In things,
The motor is characterized in that the motor is of a brushless type, the rotor is housed within the crankcase or a volume portion continuous thereto, and the windings thereof are disposed outside the crankcase.

[Function] With this configuration, when the crankcase is sealed, the rotor is housed inside the crankcase, so it can be connected to the crankshaft without a dynamic seal, and the windings are arranged outside the crankcase. Therefore, there is no need to bring cooling means into the crankcase. Therefore, this device allows power to be introduced without impairing the airtightness of the crankcase, and can also suitably cool the windings simply by configuring a simple cooling means that uses outside air, etc. becomes.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a Stirling refrigerator according to this embodiment, and the parts other than the crankcase 1 and motor 2 have the same structure as the conventional one. Therefore, common parts are given the same reference numerals and their explanations are omitted. The motor 2 is of a brushless type, and has a rotor 21 housed within the crankcase 1 and a winding 22 disposed outside the crankcase 1.

Specifically, as shown in FIGS. 2 and 3, the rotor 21 is connected to the crankshaft 109 shown in FIG.
directly or via a speed reduction mechanism. Further, the outer periphery of the rotor 2 is surrounded by a large number of magnetic poles 23 that are connected in the circumferential direction and have a convex cross section. These magnetic poles 23 are integrally attached to the inner circumference of a yoke 24 having a hollow cylindrical shape. Further, a sealing member 25 is packed between each magnetic pole 23, and the entire inner peripheral surface connected by these magnetic poles 23 and sealing member 25 forms a stator as schematically shown in FIG. A cylindrical body 11 is formed. One end of the cylindrical body 11 is connected to the main body 12 of the crankcase 1, and a cover 13 is attached to the other end to communicate the inner peripheral space of the cylindrical body 11 with the inside of the crankcase main body 12. . That is, the crankcase main body 12, the cylindrical body 11, and the cover 13 integrally form the crankcase 1 to ensure internal airtightness. Then, the crankcase 1 is filled with He gas, which is the same as that sealed in the compression chamber 104 and the expansion chamber 105.

In addition, in order to provide each magnetic pole 23 with its original function,
A winding 22 is wound around each magnetic pole 23 using the space 26 formed between the magnetic pole 23 and the yoke 24, and rotational power is applied to the rotor 21 from outside the figure to the winding 22 as appropriate. It is now possible to energize for this purpose. At this time, when the winding 22 is energized, a large amount of heat is generated due to Joule heat, etc., so a thin fan 27 is rotatably provided on the outer wall of the cover 13 described above, and outside air is drawn into the space 26 from one end of the motor 2. is introduced to generate an air flow as shown by the arrow X in FIG. 1, and removes heat from the winding 22.
It is arranged so that it can be discharged from the other end of the motor 2 to the outside.

Note that when metal is used for the sealing member 25, eddy current may occur surrounding the magnetic pole 23, so insulating members 28 are interposed at required locations to prevent this.

With such a configuration, the rotor 21 is housed within the crankcase 1 and connected to the crankshaft 109 without a dynamic seal, and the winding 22 is disposed outside the crankcase 1 and connected to the thin fan 27. Direct cooling can be achieved using outside air blown from the outside. Therefore, the crankcase 1 can be completely sealed as shown by the thick line in FIG. 1, and the cooling means only needs to be provided with a simple thin fan 27.

Note that, as shown in FIG. 4, a shell-shaped sealing member 29 may be provided further inside the inner surface of the magnetic pole 23. In this way, the sealing member 25 becomes unnecessary and a higher sealing effect can be achieved.

Although one embodiment of the present invention has been described above, the cross-sectional shape of each part is not limited to that of the illustrated embodiment, and various modifications can be made without departing from the spirit of the present invention.

[Effects of the Invention] With the above-described configuration, the present invention can provide a Stirling refrigerator with perfect measures against leakage of working gas without complicating the motor structure.

[Brief explanation of the drawing]

Figures 1 to 4 show examples of the present invention, with Figure 1 being a schematic explanatory view of the configuration, Figure 2 being a partially enlarged side sectional view, and Figure 3 being a partially enlarged side sectional view. FIG. 2 is a cross-sectional view taken along the line ■-■ in FIG. 2, and FIG. 4 is a side cross-sectional view showing a modified embodiment. Further, FIGS. 5 and 6 are explanatory diagrams corresponding to FIG. 1, respectively, showing different conventional examples. 1... Crank case 2... Motor 21... Rotor 22... Winding 102... Piston 103... Displacer 109... Crankshaft

Claims (1)

[Claims] At least a piston, a displacer, and a crankshaft are housed in a crankcase filled with working gas, and the piston and displacer are driven synchronously by a common motor via the crankshaft, wherein the motor is a brushless type. A Stirling refrigerator characterized in that the rotor is housed in a crankcase and the windings are arranged outside the crankcase.