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US-20260126219-A1 - CRYOCOOLER

US20260126219A1US 20260126219 A1US20260126219 A1US 20260126219A1US-20260126219-A1

Abstract

A cryocooler includes a cold head motor, a crank coupled to the cold head motor, a housing that accommodates the cold head motor and the crank, a bearing that supports the crank, the bearing being attached to the housing to partition the housing into two chambers together with the crank, and a pressure equalizing passage that connects the two chambers.

Inventors

  • Takaaki MORIE

Assignees

  • SUMITOMO HEAVY INDUSTRIES, LTD.

Dates

Publication Date
20260507
Application Date
20251120
Priority Date
20230928

Claims (10)

  1. 1 . A cryocooler comprising: a cold head motor; a crank coupled to the cold head motor; a housing that accommodates the cold head motor and the crank; a bearing that supports the crank, the bearing being attached to the housing to partition the housing into two chambers together with the crank; and a pressure equalizing passage that connects the two chambers.
  2. 2 . The cryocooler according to claim 1 , wherein the pressure equalizing passage is formed in the crank.
  3. 3 . The cryocooler according to claim 2 , wherein the pressure equalizing passage includes at least one through-hole extending in a direction of a rotary shaft of the cold head motor.
  4. 4 . The cryocooler according to claim 3 , wherein the crank includes a shaft hole into which the rotary shaft of the cold head motor is fitted, and a diameter of the through-hole is equal to or smaller than a diameter of the shaft hole.
  5. 5 . The cryocooler according to claim 1 , wherein the pressure equalizing passage is formed in the housing.
  6. 6 . The cryocooler according to claim 1 , further comprising: a bearing retaining member fixed to the housing and disposed adjacent to the bearing on a side of the cold head motor with respect to the bearing.
  7. 7 . The cryocooler according to claim 6 , wherein the bearing is positioned in a direction of a rotary shaft of the cold head motor between the bearing retaining member and a bearing retainer of the housing.
  8. 8 . The cryocooler according to claim 6 , further comprising: a cushioning material interposed between the bearing and the bearing retaining member.
  9. 9 . The cryocooler according to claim 1 , wherein the housing includes an exhaust port for exhausting a working gas of the cryocooler, and the two chambers are connected to the exhaust port.
  10. 10 . The cryocooler according to claim 1 , further comprising: a motion conversion mechanism including a scotch yoke shaft; a rotary valve coupled to the cold head motor via the motion conversion mechanism; and a valve support bearing that rotatably supports the rotary valve with respect to the housing, wherein the bearing that supports the crank is disposed symmetrically with the valve support bearing with respect to the scotch yoke shaft.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This is a bypass continuation of International PCT Application No. PCT/JP2024/031482, filed on Sep. 2, 2024, which claims priority to Japanese Patent Application No. 2023-168494, filed on Sep. 28, 2023, which are incorporated by reference herein in their entirety. BACKGROUND Technical Field Certain embodiments relate to a cryocooler. Description of Related Art For example, a cryocooler such as a Gifford-McMahon (GM) cryocooler includes a displacer that reciprocates to periodically change a volume of an expansion space of a working gas is known in the related art. A refrigeration cycle is configured in the cryocooler by causing a pressure in the expansion space to fluctuate in proper synchronization with periodic fluctuations in the volume of the expansion space. As one typical method for driving a reciprocating motion of the displacer, for example, there is a type in which a motor is mechanically coupled to the displacer via a motion conversion mechanism such as a scotch yoke mechanism. The motion conversion mechanism can convert a rotary motion output by the motor into a linear reciprocating motion of the displacer. SUMMARY One or more embodiments provide a cryocooler including a cold head motor, a crank coupled to the cold head motor, a housing that accommodates the cold head motor and the crank, a bearing that supports the crank, the bearing being attached to the housing to partition the housing into two chambers together with the crank, and a pressure equalizing passage that connects the two chambers. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically illustrates a cryocooler, according to an embodiment. FIG. 2 schematically illustrates the cryocooler, according to the embodiment. FIG. 3 schematically illustrates the cryocooler, according to the embodiment. FIG. 4 schematically illustrates an exploded perspective view of a main part of a driver of a cold head, according to the embodiment. FIG. 5 schematically illustrates a cryocooler, according to another embodiment. DETAILED DESCRIPTION During an operation of the cryocooler, a periodic load corresponding to intake and exhaust of a working gas acts on the displacer, thereby resulting in a load applied to the motor. In a large cryocooler having a high cooling capacity, the load applied to the motor which results from the intake and the exhaust of the working gas is likely to increase. An excessive load may cause an abnormal operation or a failure of the motor. It is desirable to improve long-term reliability of a cryocooler. Hereinafter, embodiments for implementing the present invention will be described in detail with reference to drawings. The same reference numerals are assigned to the same or equivalent components, members, and processes in the description and the drawings, and repeated description will be appropriately omitted. A scale or a shape of each shown element is set for convenience in order to facilitate the description, and is not to be interpreted in a limited manner unless otherwise specified. The embodiments are merely examples, and do not limit the scope of the present invention at all. All features or combinations thereof described in the embodiments are not necessarily essential to the invention. FIGS. 1 to 3 are views schematically showing a cryocooler 10 according to an embodiment. FIG. 1 illustrates an appearance of the cryocooler 10. FIG. 2 illustrates an internal structure of a low-temperature section of the cryocooler 10, and FIG. 3 shows an internal structure of a driver. As an example, the cryocooler 10 is a two-stage type Gifford-McMahon (GM) cryocooler. The cryocooler 10 includes a compressor 12 and an expander 14. The compressor 12 is configured to collect a working gas of the cryocooler 10 from the expander 14, to pressurize the collected working gas, and to supply the working gas to the expander 14 again. The compressor 12 and the expander 14 form a refrigeration cycle of the cryocooler 10. In this manner, the cryocooler 10 can provide desired cryogenic cooling. The expander 14 is also often referred to as a cold head. The cold head is usually installed in a vacuum container (not shown) such that a low-temperature section is disposed inside the vacuum container and a driver is disposed in a peripheral environment (for example, a room temperature atmospheric pressure environment) outside the vacuum container, and the compressor 12 is disposed in the peripheral environment. The working gas is also called a refrigerant gas, and is usually a helium gas. However, other suitable gases may be used. In order to facilitate understanding, a flow direction of the working gas is shown by an arrow in FIG. 1. In general, a pressure of the working gas supplied from the compressor 12 to the expander 14 and a pressure of the working gas collected from the expander 14 to the compressor 12 are considerably higher than the atmospheric pressure, and can be respectively referred to as a first high