Refrigeration – Gas compression – heat regeneration and expansion – e.g.,...
Reexamination Certificate
2003-02-21
2004-08-24
Tyler, Cheryl J. (Department: 3744)
Refrigeration
Gas compression, heat regeneration and expansion, e.g.,...
Reexamination Certificate
active
06779349
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a refrigerating system provided with a Stirling refrigerating device, and to a cooling apparatus such as a refrigerator employing such a refrigerating system.
2. Description of Related Art
In general, refrigerating cycle apparatuses such as household refrigerators adopt a vapor compression refrigerating cycle using a CFC (chlorofluorocarbon) as a refrigerant. As is well known, however, CFCs are notorious for their material contribution to the destruction of the ozone layer and, from the perspective of saving the environment, their use is increasingly restricted worldwide.
In recent years, as new refrigerating technology to replace the vapor compressing refrigerating cycle, much research has been done on Stirling refrigerating devices exploiting the reversed Stirling cycle. A Stirling refrigerating device uses an inert gas such as helium as a working medium, and therefore provides a cryogenic temperature efficiently without adversely affecting the global environment.
The reversed Stirling cycle is a closed cycle in which heat rejection and heat absorption are performed by repeatedly compressing and expanding a working medium together with a displacer driven to reciprocate with a predetermined phase difference kept relative to a piston inside a single cylinder by driving the cylinder with an external force fed from a linear motor or the like.
A Stirling refrigerating device requires a means for efficiently transferring the cold obtained in a low-temperature portion, called the cold section, thereof. Moreover, the higher the refrigeration performance of the Stirling refrigerating device, the larger the amount of heat generated in a heat-rejection portion, called the warm section, thereof, and therefore, unless the generated heat is efficiently rejected, the Stirling refrigerating device shows poor refrigeration performance, producing less cold than expected in its cold section.
For example, in the Stirling refrigerator disclosed in Japanese Patent Application Laid-Open No. H7-180921, as shown in
FIG. 20
, a cooler
101
for cooling the interior of the refrigerator is arranged in a highest, deepest position inside the body
100
of the refrigerator, and a Stirling refrigerating device
102
is housed inside a machine compartment at the bottom of the body. The cold section
103
of the Stirling refrigerating device
102
is connected to the cooler
101
by way of a pipe
104
filled with a working medium, and the working medium is circulated so that, when the Stirling refrigerating device
102
is operated, the cold generated in the cold section
103
is transferred by the working medium to the cooler
101
placed inside the refrigerator.
Then, the cold air obtained through heat exchange taking place on the surface of the cooler
101
between the cold transferred to the cooler
101
and the air inside the refrigerator is blown into the refrigerator interior by a fan
105
, so that the refrigerator interior is cooled to a predetermined temperature. On the other hand, in the warm section
106
of the Stirling refrigerating device
102
, heat-rejecting fins
107
are arranged, and air is blown therethrough by a blower fan
108
to prompt heat rejection from the warm section
106
.
However, while refrigeration performance of the order of a few hundred watts is required in Stirling refrigerators for which high demands are expected as models for household and commercial use, attempting to achieve such refrigeration performance with the conventional construction described above results in extremely increasing the surface area of the heat-rejecting fins
107
and the amounts of cooling air blown by the blower fan
108
.
This makes the refrigerating system as a whole larger, and thus makes it necessary to secure, for the machine compartment, a volume as large as or larger than in a conventional refrigerator of the vapor compression type. This not only makes it inevitable to reduce the volume of the remaining space inside the refrigerator, but also, as a result of increased electric power consumption by the fan, degrades the efficiency of the system as a whole, contrary to energy saving.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a compact Stirling refrigerating system with enhanced refrigeration efficiency achieved by prompting heat rejection from the warm section.
To achieve the above object, according to one aspect of the present invention, a Stirling refrigerating system is provided with: a Stirling refrigerating device including a piston and a displacer that reciprocate with a predetermined phase difference kept therebetween inside a cylinder having a working medium sealed therein, a heat absorber that absorbs heat from outside to produce cold as a result of the working medium being expanded in an expansion space formed inside the cylinder as the displacer reciprocates, and a heat rejecter that rejects, to outside, heat generated as a result of the working medium being compressed in a compression space formed inside the cylinder as the piston reciprocates; a ring-shaped member fitted to the heat rejecter and having a refrigerant flow passage; a cylindrical heat-rejecting heat exchanger disposed around the Stirling refrigerating device with a gap secured in between and formed so as to have a refrigerant flow passage; a refrigerant circulation passage formed by connecting the refrigerant flow passage of the ring-shaped member and the refrigerant flow passage of the heat-rejecting heat exchanger with a pipe; and circulating means for circulating a refrigerant through the refrigerant circulation passage.
Specifically, the heat-rejecting heat exchanger is composed of a first header pipe having at one end thereof a connection port to which one end of the pipe is connected, a second header pipe laid next to the first header pipe and parallel, together with the first header pipe, to the axis of the Stirling refrigerating device and having at one end thereof a connection port to which the other end of the pipe is connected, a plurality of ring-shaped condenser pipes that connect the first and second header pipes together so that they communicate with each other therethrough, and fins fitted between the plurality of condenser pipes. In this construction, the refrigerant that has collected compression heat in the compression space flows through the pipe into the second header pipe, and then flows through the ring-shaped condenser pipes into the first header pipe. Meanwhile, the compression heat is transferred to the fins, and is efficiently rejected from the surfaces of the fins. In this case, the condenser pipes and the fins may be given substantially equal lengths in the radial directions of the Stirling refrigerating device. This helps increase the surface area of the fins that contributes to heat rejection.
On the other hand, the transferring means comprises a cylindrical rod slide portion formed at the end of the Stirling refrigerating device opposite to the heat absorber, a rod slidable together with the piston along the inner surface of the rod slide portion, a first magnet fitted at the tip end of the rod, a box member fitted at the tip end of the rod slide portion and forming part of the refrigerant circulation passage, a resonant spring placed inside the box member and having the rod slide portion placed therethrough, a second magnet slidable along the outer surface of the rod slide portion by the action of the resonant spring, and a movable member fixed to the second spring and capable of reciprocating along the outer surface of the rod slide portion and along the inner surface of the box member. The refrigerant that has flowed into the box member is discharged out of it by the pumping action of reciprocating movement of the movable member.
In this construction, as the piston reciprocates, the first magnet fitted at the tip end of the rod reciprocates together, and, by the magnetism it exerts, the second magnet also reciprocates along the outer surface of the rod slide
Birch & Stewart Kolasch & Birch, LLP
Drake Malik N.
Sharp Kabushiki Kaisha
Tyler Cheryl J.
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