Hermetic compressor

Details Hermetic compressor Hermetic compressor

1999-07-06

2001-03-27

Ryznic, John E. (Department: 3745)

Pumps

Expansible chamber type

Moving cylinder

C417S463000, C417S902000

Reexamination Certificate

active

06206661

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a hermetic compressor used in a refrigeration cycle system.
BACKGROUND ART
There is a conventionally proposed principle of a compressing mechanism which includes a rotary cylinder having a groove, and a piston slidable within the groove, so that the rotary cylinder is rotated in accordance with the movement of the piston to perform suction and compression strokes (for example, see German Patent No. 863,751 and British Patent No. 430,830).
The conventionally proposed principle of the compressing mechanism will be described below with reference to FIG.
16
.
The compressing mechanism is comprised of a rotary cylinder
101
having a groove
100
, and a piston
102
which is slidable within the groove
100
. The rotary cylinder
101
is provided for rotation about a point A, and the piston
102
is rotated about a point B.
The movements of the piston and the cylinder will be described as for a case where the rotational radius of the piston
102
is equal to the distance between the center A of rotation of the rotary cylinder
101
and the center B of rotation of the piston
102
. When the rotational radius of the piston
102
is larger or smaller than the distance between the rotational center A of the rotary cylinder
101
and the rotational center B of the piston
102
, different movements are performed. The description of these different movements is omitted herein.
A broken line C in
FIG. 16
indicate a locus for the piston
102
.
FIGS. 16
a
to
16
i
show states in which the piston
102
has been rotated sequentially through every 90 degree.
First, the movement of the piston
102
will be described below.
FIG. 16
a
shows the state in which the piston
102
lies immediately above the rotational center B.
FIG. 16
b
shows the state in which the piston
102
has been rotated through 90 degree in a counterclockwise direction from the state shown in
FIG. 16
a.
FIG. 16
c
shows the state in which the piston
102
has been further rotated through 180 degree in the counterclockwise direction from the state shown in
FIG. 16
a.
FIG. 16
d
shows the state in which the piston
102
has been further rotated through 270 degree in the counterclockwise direction from the state shown in
FIG. 16
a.
FIG. 16
e
shows the state in which the piston
102
has been rotated through 360 degree in the counterclockwise direction from the state shown in
FIG. 16
a
and has been returned to the state shown in
FIG. 16
a.
The movement of the rotary cylinder
101
will be described below.
In the state shown in
FIG. 16
a,
the rotary cylinder
101
is located, so that the groove
100
is located vertically. When the piston
102
is moved through 90 degree in the counterclockwise direction from this state, the rotary cylinder
101
is rotated through 45 degree in the counterclockwise direction, as shown in
FIG. 16
b
and hence, the groove
100
is likewise brought into a state in which it is inclined at 45 degree. When the piston
102
is rotated through 180 degree in the counterclockwise direction from the state shown in
FIG. 16
a,
the rotary cylinder
101
is rotated through 90 degree in the counterclockwise direction, as shown in
FIG. 16
c
and hence, the groove
100
is likewise brought into a state in which it is inclined at 90 degree.
In this way, the rotary cylinder
101
is rotated in the same direction with the rotation of the piston
102
, but while the piston
102
is rotated through 360 degree, the rotary cylinder
101
is rotated through 180 degree. Therefore, to rotate the rotary cylinder
101
through 360 degree, it is necessary to rotate the piston
102
through 720 degree.
The change in volume of the groove
100
defining the compressing space will be described below.
In the state shown in
FIG. 16
a,
the piston
102
lies at one end in the groove
100
and hence, only one space exists. This space is called a first space
100
a
herein. In the state shown in
FIG. 16
b,
the first space
100
a
is narrower, but a second space
100
b
is produced on the opposite side of the piston
102
. In the state shown in
FIG. 16
c,
the first space
100
a
is further decreased into a size as small as half of the space in the state shown in
FIG. 16
a,
but a second space
100
b
is of the same size as the first space
100
a.
The first space
100
a
is gradually decreased, as shown in
FIG. 16
d,
and is zero in volume in the state shown in
FIG. 16
e
in which the piston
102
has been rotated through 360 degree.
In this way, the first and second spaces
100
a
and
100
b
are defined in the groove
100
by the piston
102
and repeatedly varied in volume from the minimum to the maximum and from the maximum to the minimum, whenever the piston
102
is rotated through 360 degree.
Therefore, the spaces defining the compressing chambers perform the compression and suction strokes by the rotation of the piston
102
through 720 degree.
When the compressing mechanism is provided in the casing or bearing and operated, the compressing chambers are defined, so that they are surrounded by the outer peripheral surface of the piston, the wall surface of the groove in the rotary cylinder and end faces of the bearing. The surfaces of respective members defining the compressing chambers are slid on the opposed surfaces. The clearance between the slide faces is set at a small value in order to suppress the leakage of a refrigerant gas in the compressing course to the minimum, and a lubricating oil is supplied into the clearance in order to provide a lubricating effect and a sealing effect.
In such case, when two faces are rotationally slid on each other with the lubricating oil present therebetween, such as the end face of the rotary cylinder and the end face of the bearing, or the end face of the piston and the end face of the bearing, a power loss is produced due to the viscosity of the lubricating oil.
The power loss Ws due to the viscosity is represented by the following equation:
Ws=&pgr;&mgr;&ohgr;
2
(
r
2
4
−r
1
4
)/(2&dgr;)
wherein &mgr; is a viscosity coefficient of the oil; &ohgr; is a rotational angular speed; r
2
is an outside diameter of the slide face; r
1
is an inside diameter of the slide face; and &dgr; is a distance between the slide faces. Thus, the loss Ws due to the viscosity assumes a larger value in proportion to the fourth power of the radius of the slide face.
On the other hand, the power loss Wr produced due to viscosity between the slide faces of the outer peripheral surface of the rotary cylinder and the inner peripheral surface of the casing is represented by the following equation:
Wr
=2&pgr;&mgr;&ohgr;
2
R
3
W/&dgr;
wherein R is an outside diameter of the rotary cylinder; and W is a width of the rotary cylinder. The power loss Wr assumes a value proportional to the product of the third power of the outside diameter of the rotary cylinder and the width of the rotary cylinder.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to ensure that in view of the power loss produced due to the viscosity between the slide faces, the viscosity is lowered, while ensuring the sealability, and the loss in power of the compressor is reduced to enhance the compression efficiency.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided a hermetic compressor, comprising compressing mechanisms provided in a casing, each of the compressing mechanisms including a rotary cylinder having a groove, and a piston slidable in the groove, so that the suction and compression are carried out by rotation of the piston on a locus of a radius E about a point spaced at a distance E apart from the center of the rotary cylinder, opposite end faces of the casing being sandwiched between bearings, wherein a recess, which does not communicate with the groove, is defined in that end face of the rotary cylinder which is a slide face relative to the bearings.
With the above arrangement, the power loss produced due to the viscosity the rotary cylinder and th

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