Stirling engine

Details Stirling engine Stirling engine

2003-05-30

2004-08-24

Nguyen, Hoang M. (Department: 3748)

Power plants

Motor operated by expansion and/or contraction of a unit of...

Unit of mass is a gas which is heated or cooled in one of a...

C060S517000

Reexamination Certificate

active

06779342

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a Stirling cycle engine provided with a regenerator that offers improved heat exchange efficiency.
BACKGROUND ART
A conventional Stirling cycle engine is provided with, for example, a regenerator as shown in
FIG. 6
, which is composed of a cylindrical bobbin
3
around the outer surface of which is wound a resin film
2
having very fine irregularities
11
formed on the surface thereof so that gaps are left between different layers of the resin film
2
. These gaps result from the resin film
2
having the fine irregularities
11
between different layers thereof.
FIG. 7
is a side sectional view of an example of a free-piston-type Stirling cycle refrigerator provided with such a regenerator
1
. First, the structure and operation of this free-piston-type Stirling cycle refrigerator
14
will be described.
As shown in
FIG. 7
, the free-piston-type Stirling cycle refrigerator
14
is provided with an enclosure
6
having working gas such as helium sealed therein, a displacer
17
and a piston
18
that divide the space inside the enclosure
6
into an expansion space
20
and a compression space
19
, a linear motor
21
for driving the piston
18
to reciprocate, a heat absorber
12
provided by the side of the expansion space
20
so as to absorb heat from outside, and a heat rejector
13
provided by the side of the compressed space
19
so as to reject heat to outside.
In
FIG. 7
, reference numerals
22
and
23
represent flat springs that support the displacer
17
and the piston
18
, respectively, to permit them to reciprocate under their resilience. Reference numeral
15
represents a heat-rejecting heat exchanger, and reference numeral
16
represents a heat-absorbing heat rejector. These serve to prompt the exchange of heat between the inside and outside of the free-piston-type Stirling cycle refrigerator
14
. Between the heat-rejecting heat exchanger
15
and the heat-absorbing heat rejector
16
is provided the regenerator.
In this structure, when the linear motor
21
is driven, the piston
18
moved upward inside the enclosure
6
, and compresses the working gas in the compression space
19
. Here, the working gas becomes warmer as it is compressed, but simultaneously it is cooled by exchanging heat with the outside air through the heat-rejecting heat exchanger
15
. Thus, the process that takes place here is isothermal compression.
Then, the displacer
17
, which is so controlled as to reciprocate with a predetermined phase difference kept relative to the piston
18
, starts moving downward, and thus the working gas in the compression space
19
is passed through the regenerator
1
to the expansion space
20
. Meanwhile, the heat of the working gas is accumulated in the resin film
2
forming the regenerator
1
, and thus the working gas becomes cooler.
Next, the piston
18
moves downward, and expands the working gas in the expansion space
20
. Here, the working gas becomes cooler, but simultaneously it is heated by absorbing heat from the outside air through the heat absorber
12
. Thus, the process that takes place here is isothermal expansion.
Then, the displacer
17
starts moving upward, and thus the working gas in the expansion space
20
is passed through the regenerator I back to the compression space
19
. Meanwhile, the working gas receives the heat accumulated in the regenerator
1
, and thus becomes warmer. This sequence of events, which together constitute the reversed Stirling cycle, is repeated by the reciprocating movement of the driver, and as a result the heat absorber
12
continues absorbing heat from the outside air and thereby gradually makes it cooler and cooler.
As described above, in the Stirling cycle refrigerator that permits cold to be extracted at the heat rejector
12
by making the working gas reciprocate between the compression space
19
and the expansion space
20
through the regenerator
1
, the regenerator
1
accumulates the heat of the compressed, warm working gas and then returns the accumulated heat to the expanded, cool working gas in such a way as to collect cold. Therefore, the larger the amount of heat accumulated in the regenerator, the more efficiently heat can be used, and thus the higher the performance of the Stirling cycle refrigerator can be made.
However, with the regenerator
1
structured as described above, when the resin film
2
wound around the outer surface of the cylindrical bobbin
3
is fitted into the free-piston-type Stirling cycle refrigerator
14
, the outer surface of the resin film
2
is not fixed on the inner surface of the enclosure
6
. Thus, the working gas tends to leak between the outer surface of the resin film
2
and the inner surface of the enclosure
6
. The working gas that so leaks flows between the compression space and the expansion space without contributing to the heat exchange taking place in the regenerator
1
. This causes a large loss of heat, and thus lowers the performance of the Stirling cycle engine.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a Stirling cycle engine that operates with a reduced loss of heat due to gas leakage by the use of a regenerator so structured as to easy and inexpensive to manufacture and thus with increased heat exchange efficiency in the regenerator.
To achieve the above object, according to the present invention, in a Stirling cycle engine provided with a regenerator arranged between a compression space and an expansion space so as to serve as a flow passage for working gas reciprocated between the compression and expansion spaces and operate by collecting heat from or releasing heat to the working gas, the regenerator is provided with a bobbin, a resin film wound around the outer surface of the bobbin so as to be kept in intimate contact therewith, and a sheath fitted around the outer surface of the resin film and having a slit formed in a longitudinal direction. Here, one end of the resin film is firmly fitted to the outer surface of the bobbin, the outer surface of the resin film is kept in intimate contact with the sheath, and the working gas flows between different layers of the resin film.
In this structure, no gap is left between the resin film and the sheath nor between the resin film and the bobbin, and thus the working gas does not leak. This helps improve the heat exchange efficiency in the regenerator.
Alternatively, according to the present invention, in a Stirling cycle engine provided with a regenerator arranged between a compression space and an expansion space so as to serve as a flow passage for working gas reciprocated between the compression and expansion spaces and operate by collecting heat from or releasing heat to the working gas, the regenerator is provided with a bobbin, a resin film wound around the outer surface of the bobbin, and a sheath fitted around the outer surface of the resin film and having a slit formed vertically therein. Here, the resin film has one end fixed on the outer surface of the bobbin, and has the other end led out through the slit and fixed to an end surface of the slit or to the outer surface of the sheath. Moreover, the working gas flows between different layers of the resin film.
In this structure, it is possible to minimize the gaps between the resin film and the sheath and between the resin film and the bobbin. This helps improve the heat exchange efficiency in the regenerator.
Alternatively, according to the present invention, in a Stirling cycle engine provided with a regenerator arranged inside an enclosure provided between a compression space and an expansion space so as to serve as a flow passage for working gas reciprocated between the compression and expansion spaces and operate by collecting heat from or releasing heat to the working gas, the regenerator is provided with a bobbin, a resin film wound around the outer surface of the bobbin, and a sheath fitted around the outer surface of the resin film and having a slit formed vertically therein. Here, the resin film has one end fixed on the ou

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