Refrigeration – Gas compression – heat regeneration and expansion – e.g.,...
Reexamination Certificate
2003-05-30
2004-11-09
Doerrler, William C. (Department: 3744)
Refrigeration
Gas compression, heat regeneration and expansion, e.g.,...
C062S335000
Reexamination Certificate
active
06813892
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relatives to the field of cryocoolers having multiple cryocooler sections and, more particularly, to allowing for the use of one charge pressure source and pressure oscillator for one cryocooler section, and for the use of at least one other charge pressure source and pressure oscillator for a different cryocooler section.
BACKGROUND OF THE INVENTION
Various configurations of pulse tube cryocoolers are known for providing cooling in a number of applications. Pulse tube cryocoolers may provide cooling for electronics and the like on board extraterrestrial spacecraft. One way to categorize pulse tube cryocoolers is in relation to the number of stages that are utilized. Single stage pulse tube cryocoolers are typically operated at a comparatively high pressure for operating efficiency purposes, and can provide cooling down to about 60 K. Multiple stage pulse tube cryocoolers arranged in series (generally, where one pulse tube stage “precools” another pulse tube stage) are usually required to realize cooling temperatures of 50 K or below. These multi-stage types of pulse tube cryocoolers are typically operated at lower pressures than the above-noted single stage pulse tube cryocoolers in order to realize a desired operating efficiency.
There are pulse tube cryocooler designs having what may be characterized as multiple cryocooler sections. For instance, a first cryocooler section may include a single pulse tube stage, while a second cryocooler section may include multiple pulse tube stages. The first cryocooler section may provide precooling for the second cryocooler section in this type of design. However, the first and second cryocooler sections utilize a common charge pressure. Therefore, it should be appreciated that using this type of pressure source may not allow the first and second cryocooler sections to each operate at a desired efficiency since both the first and second cryocooler sections will be charged at the same mean pressure. Both the first and second cryocooler sections are also exposed to the same pressure oscillation in known designs. This common pressure oscillator may be in the form of a dual-piston compressor. Compressors of this type utilize what may be characterized as opposing pistons in a common compression space. Each piston is operated at the same frequency by the same drive. However, the pistons are moved through the common compression space in opposite directions to reduce vibrations. Therefore, it should be appreciated that using this type of pressure oscillator may not allow the first and second cryocooler sections to each operate at a desired efficiency since both the first and second cryocooler sections will undergo the same pressure oscillation.
BRIEF SUMMARY OF THE INVENTION
A first aspect of the present invention is generally directed to a cryocooler. This cryocooler includes at least two separate cryocooler sections (hereafter first and second cryocooler sections, although more cryocooler sections could of course be utilized). The first cryocooler section includes at least two stages, each having at least one pulse tube (hereafter first and second stages), while the second cryocooler section includes at least one stage, each having at least one pulse tube (hereafter a second cryocooler section first stage). Pressure oscillations for the first and second cryocooler sections are generated by a first pressure oscillator that is fluidly interconnected with the first cryocooler section and a second pressure oscillator that is fluidly interconnected with the second cryocooler section. The first pressure oscillator does not generate a pressure oscillation within the second cryocooler section. Similarly, the second pressure oscillator does not generate a pressure oscillation within the first cryocooler section. Stated another way, the first pressure oscillator is not fluidly interconnected with the second cryocooler section, and the second pressure oscillator is not fluidly interconnected with the first cryocooler section. Stated yet another way, the first and second cryocooler sections are fluidly isolated from each other. This then allows the charge pressures in the first and second cryocooler sections to be selected/established independently of each other. That is, the charge pressure that may be used in the first cryocooler section need not be dependent upon the charge pressure that is used in the second cryocooler section, and vice versa. Although the first and second cryocooler sections will typically each be charged with a gas, the first aspect also encompasses using any appropriate fluid. Hereafter, references will be made to having a fluid or a working fluid in the first and second cryocooler sections, each of which are closed systems.
Various refinements exist of the features noted in relation to the first aspect of the present invention. Further features may also be incorporated in the first aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. Any configuration/size/type of stage may be utilized by the first and second cryocooler sections, and including having its components (e.g., one or more regenerators, one or more heat exchangers, one or more pulse tubes, one or more flow impedance devices) being of any appropriate configuration/size/type and disposed in any appropriate relative arrangement. For instance, one or more of the stages may be of the inertance-type (having an inertance tube that interfaces with one end of a pulse tube that is opposite the end of this pulse tube that interfaces with a coldhead, where the inertance tube is disposed between a fluid reservoir and this pulse tube). One or more of the stages also may be of the orifice-type (having an orifice in a fluid line that interfaces with one end of a pulse tube that is opposite the end of this pulse tube that interfaces with a coldhead, where the orifice is disposed between a fluid reservoir and this pulse tube). Any type of flow impedance device (e.g., an orifice, valve, porous plug, inertance tube, vortex tube) may be used in conjunction with each stage of the cryocooler of the first aspect. Each stage will typically have only a single pulse tube, although a stage having multiple pulse tubes would be encompassed by this first aspect.
The first cryocooler section in the case of the first aspect may be characterized as a multi-stage side of the cryocooler (e.g., the first and second stages), while the second cryocooler section may be in the form of a single stage side of the cryocooler (i.e., the second cryocooler section first stage). Such a first stage for the first cryocooler section may include a first regenerator, a first pulse tube, and first, second, and third heat exchangers. The first pressure oscillator is fluidly interconnected with the first stage, the first heat exchanger may be associated with a first part of the first regenerator (e.g., a first hot end heat exchanger), the second heat exchanger may be associated with both a second part of the first regenerator and a first part of the first pulse tube (e.g., a first cold end heat exchanger), and the third heat exchanger may be associated with a second part of the first pulse tube (e.g., a first pulse tube heat exchanger). Similarly, such a second stage for the first cryocooler section may include a second regenerator, a second pulse tube, and fourth, fifth, and sixth heat exchangers. The first pressure oscillator is also fluidly interconnected with the second stage, the first stage may precool the second stage, the fourth heat exchanger may be associated with a first part of the second regenerator (e.g., a second hot end heat exchanger), the fifth heat exchanger may be associated with both a second part of the second regenerator and a first part of the second pulse tube (e.g., a second cold end heat exchanger), and the sixth heat exchanger may be associated with a second part of the second pulse tube (e.g., a second pulse tube heat exchanger). Finally, such a second cryocooler sec
Champagne Patrick J.
Olson Jeffrey R.
Doerrler William C.
Lockheed Martin Corporation
Marsh & Fischmann & Breyfogle LLP
LandOfFree
Cryocooler with multiple charge pressure and multiple... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cryocooler with multiple charge pressure and multiple..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cryocooler with multiple charge pressure and multiple... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3336885