Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
2001-11-06
2003-11-04
Tyler, Cheryl J. (Department: 3746)
Pumps
Motor driven
Electric or magnetic motor
C417S416000, C417S419000, C417S488000
Reexamination Certificate
active
06641377
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a compressor for use in a cryogenic refrigerator.
Compressors of this kind are described in Japanese Patent No. 2522424 and Japanese Patent Publications (KOKAI) No. 5-288419 and No. 8-110110.
FIG. 9
is a vertical sectional view showing a compressor disclosed in Japanese Patent Publication No. 8-110110, and
FIG. 10
is a vertical sectional view showing only a movable portion thereof. In
FIGS. 9 and 10
, a piston
3
is inserted into a cylinder having a cylindrical space, via a gap
2
, to form an operating-gas-compressing space
5
in the cylindrical space of the cylinder
1
enclosed by a cylinder head
4
. A piston shaft
6
is coaxially secured to the piston
3
. The piston
3
is supported by two support springs
7
and
8
for free reciprocation in the axial direction. The support springs
7
and
8
are composed of plate springs attached to the piston shaft
6
with an axial gap formed therebetween.
The piston
3
is driven by a linear drive section
9
to reciprocate in the axial direction. The linear drive section
9
includes a driver coil
11
wound around a coil bobbin
10
secured to the piston shaft
6
, and a magnetic circuit having a void
12
in which the driver coil
11
is accommodated. The magnetic circuit is formed by an annular magnet
13
, and a flanged cylindrical yoke
14
and an annular yoke
15
arranged on the respective sides of the magnet
13
. The yoke
14
has a cylindrical frame
16
connected thereto, and the frame
16
has a bottomed two-stage cylindrical frame
17
connected thereto. The cylinder head
4
, the cylinder
1
, the yoke
4
, and the frames
16
and
17
constitute one pressure container generally forming a gas chamber
34
. The gas chamber
34
leads to the compressing space
5
via the gap
2
.
Here, a procedure of assembling a major portion of the compressor in
FIG. 9
will be described. The yokes
14
and
15
are stuck to and integrated with the permanent magnet
13
by using an adhesive. The frame
16
is combined with the integrated parts, and the combined parts are tightened together using screws (not shown). Then, the support spring
7
is combined with the yoke
14
from above in
FIG. 9
via their fitting portions, and these combined parts are tightened together by using screws (not shown). Then, the piston shaft
6
, integrated with the piston
3
, is inserted into a central hole in the support spring
7
from above. Furthermore, an interval tube
18
, a coil bobbin
10
, a washer
19
, a sleeve
20
, and the support spring
8
are sequentially fitted on the piston shaft
6
from below as shown in FIG.
10
. At the same time, the support spring
8
is combined with the frame via their fitting portions, and the combined parts are tightened by using screws (not shown).
Further, on the piston shaft
6
, the support spring
7
, the interval tube
18
, the coil bobbin
10
, the washer
19
, the sleeve
20
, and the support spring
8
are tightened between the piston
3
and a washer
21
by a nut
22
. Subsequently, the frame
17
is combined with the frame
16
via their fitting portions and secured thereto by fillet welding. Reference numerals
23
a
and
23
b
denote a movable portion and a fixed portion, respectively, of a displacement sensor for detecting the axial displacement of the piston
3
. The movable portion
23
a
is attached to the piston shaft
6
after tightening the nut
22
. As described above, a unit formed of the piston
3
, the support springs
7
and
8
, the yokes
14
and
15
, the frames
16
and
17
, and others, which are integrally assembled, is inserted into the cylinder
1
, which is separately supported on an assembly frame. The piston
3
is carefully aligned, and the yoke
14
is then tightened against the cylinder
1
by using a screw
24
.
In such a compressor, magnetic fluxes generated by the permanent magnet
13
return from the N pole surface thereof through the yoke
15
, the void
12
, and the yoke
14
to the S pole surface thereof. Thus, when a current is periodically conducted through the driver coil
11
, a magnetic force is generated between this current and the magnetic fields in the void
12
to reciprocate the piston
3
in the axial direction, thereby compressing an operating gas in the compressing space
5
. A pressure wave from the compressed gas is applied to a cryogenic refrigerator (not shown) through a gas channel
25
in the cylinder head
4
.
The above conventional compressor has the following problems.
(1) The piston
3
has the piston shaft
6
secured thereto, the piston shaft
6
has the linear drive section
9
arranged radially outside the piston shaft
6
, and the support springs
7
and
8
are arranged on the respective sides of the linear drive section
9
in the axial direction. Thus, the piston
3
, the linear drive section
9
, and the plurality of springs
7
and
8
are linearly arranged in the axial direction, resulting in a long movable portion to increase the longitudinal dimension of the compressor.
(2) Between the support springs
7
and
8
, the fitting portions are present between the support spring
7
and the yoke
14
, between the yoke
14
and the frame
16
, and between the frame
16
and the support spring
8
. Accordingly, parts and assembly errors may be accumulated in the fitting portions to cause misalignment between the support springs
7
and
8
. This misalignment may incline the axis of the piston
3
to the cylinder
1
to bring the piston and the cylinder into contact with each other, thus causing friction therebetween.
(3) For assembly, the support spring
7
and the piston
3
are inserted from one side (from the upper side in
FIG. 9
) of the linear drive section
9
in the axial direction, and the interval tube
18
, the coil bobbin
10
, and the support spring
8
, and others are inserted from the other side (from the lower side in FIG.
9
). Consequently, one-direction assembly can not be made on the linear drive section
9
, preventing an easy assembly operation.
Thus, the object of the present invention is to solve these problems by decreasing the size of compressor, increasing the accuracy thereof, and allowing the compressor to be assembled more easily.
SUMMARY OF THE INVENTION
The present invention provides a compressor comprising a cylinder having a cylindrical space, a piston inserted into the cylinder via a gap forming a clearance seal, the piston forming an operating-gas-compressing space in the cylindrical space, support springs composed of a plate spring for supporting the piston for free reciprocation in the axial direction, a linear drive section for driving the piston to reciprocate in the axial direction, and a pressure container that forms a gas chamber leading to the compressing space via the gap. The linear drive section is formed by a driver coil connected to the piston, and a magnetic circuit composed of a permanent magnet having a void in which the driver coil is located. The spring is arranged at an interval at the end of the corresponding piston which is opposite to the compressing space, and the linear drive section is arranged radially outside the compressing-space-side end of the piston (a first aspect of the invention).
According to the first aspect of the invention, one end of the piston is supported by the plurality of support springs in a cantilever manner, and the linear drive section is arranged radially outside the other end of the piston. Accordingly, the entire length of movable portion can be shorter than that of the piston, so that the longitudinal dimension of the compressor can be decreased. Further, since the plurality of support springs is arranged together at one side of the linear drive section, a surface of the compressor main body on which the support springs are fitted can be shared easily by the support springs. Consequently, the support springs can be more accurately aligned with each other, and the plurality of support springs can be assembled on the linear drive section from one direc
Ohshima Keishi
Toyama Kentaro
Yasukawa Yukio
Fuji Electric & Co., Ltd.
Kanesaka & Takeuchi
Sayoc Emmanuel
Tyler Cheryl J.
LandOfFree
Linear compressor with a plurality of support springs and a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Linear compressor with a plurality of support springs and a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Linear compressor with a plurality of support springs and a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3147881