[0001] This application claims the benefit of Korean Patent Application No.
10-2008-0094154 filed on September 25, 2008, in the Korean Intellectual Property Office, the disclosure of which is incorporated
herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the invention
[0002] The present invention relates to a cylinder and a rotary compressor having the same.
More particularly, the present invention relates to a rotary compressor using carbon
dioxide coolant that is natural coolant.
2. Description of the Related Art
[0003] Recently, with the increase in interest for environment, hydro-fluorocarbon (HFC)
that does not destroy an ozone layer is used as coolant in order to prevent depletion
of the ozone layer and global warming. In addition, studies and development regarding
a compressor using natural coolant having a low global warming coefficient have been
actively performed.
[0004] Under such a circumstance, carbon dioxide (CO
2) is spotlighted as environmental-friendly natural coolant having no problems in relation
to toxicity and flammability. Thus, a rotary compressor using such CO
2 as coolant is also spotlighted.
[0005] In a rotary compressor using the CO
2 as coolant, since the coolant has a high-pressure characteristic, a whole cooling
cycle must be designed to have pressure-resistance characteristics. In addition, if
the CO
2 is used as coolant, pressure difference between both surfaces of a vane is at least
three times greater than a case
where existing coolant such as R410A is used and force applied to a contact surface
between the vane and a roller is remarkably increased, so that it is necessary to
cope with gas leakage occurring during a compression operation of a compressing chamber
due to structural deformation, abrasion caused by friction, and shaft deformation.
[0006] In other words, as shown in FIG. 7, when gas introduced into a suction port 1 is
discharged through a discharge port 5 after the gas is changed to a high-pressure
state in a compressing chamber 2 due to eccentric rotation motion of the roller 6
and reciprocation motion of a vane 4, gas leakage mainly occurs at lateral side surfaces
of the vane 4 having the highest pressure difference, a contact surface between a
front end of the vane 4 and a roller 6, and a contact surface between the roller 6
and an inner surface of a cylinder 3 as indicated by arrows.
[0007] Accordingly, studies and research have been carried out to improve volumetric efficiency
by injecting oil together with suction gas to minimize a gap causing the gas leakage
through a sealing function of an oil film.
SUMMARY OF THE INVENTION
[0008] Accordingly, it is an aspect of the present invention to provide a rotary compressor
capable of improving sealing performance using oil.
[0009] Additional aspects and/or advantages of the invention will be set forth in part in
the description which follows and, in part, will be apparent from the description,
or may be learned by practice of the invention.
[0010] The foregoing and/or other aspects of the present invention are achieved by providing
a rotary compressor including a cylinder, which includes a compressing chamber receiving
a roller, a suction port supplying a fluid to the compressing chamber, and a vane
groove receiving a vane and allowing the vane to reciprocate in the vane groove such
that the compressing chamber is divided into a suction area and a discharge area by
the vane, and an expansion groove formed adjacent to an outlet of the suction port
and obtained by enlarging a sectional area of the suction port.
[0011] According to an aspect of the present invention, upper and lower portions of the
expansion groove are open.
[0012] According to an aspect of the present invention, the cylinder is provided with an
oil supply passage connecting the expansion groove with the vane groove.
[0013] According to an aspect of the present invention, the oil supply passage has a stepped
portion on at least one of top and bottom surfaces of the cylinder.
[0014] According to an aspect of the present invention, the stepped portion of the oil supply
passage has a height in a range of 0.05 mm to 0.2 mm.
[0015] According to an aspect of the present invention, the oil supply passage comprises
a guide unit guiding a direction of oil to one side of a side surface of the vane
groove, and the guide unit is inclined from the expansion groove to a front end of
the vane groove.
[0016] According to an aspect of the present invention, the oil supply passage comprises
a guide unit guiding a direction of oil to one side of a side surface of the vane
groove, and the guide unit is curved from the expansion groove to a front end of the
vane groove.
[0017] According to an aspect of the present invention, the fluid introduced into the suction
port is mixture of oil and carbon dioxide that is natural coolant.
[0018] It is another aspect of the present invention to provide a rotary compressor including
a cylinder, which includes a compressing chamber receiving a roller, a suction port
supplying a fluid to the compressing chamber, and a vane groove receiving a vane and
allowing the vane to reciprocate in the vane groove such that the compressing chamber
is divided into a suction area and a discharge area by the vane. In this case, the
suction port is formed with an outlet having a size identical to a height of an inner
circumferential surface of the cylinder.
[0019] According to another aspect of the present invention, the rotary compressor includes
an oil supply passage configured to be stepped between an expansion groove and the
vane groove.
[0020] It is still another aspect of the present invention to provide a rotary compressor
including a cylinder, which includes a compressing chamber receiving a roller, a suction
port supplying a fluid to the compressing chamber, and a vane groove receiving a vane
and allowing the vane to reciprocate in the vane groove such that the compressing
chamber is divided into a suction area and a discharge area by the vane. In this case,
the suction port is formed with an outlet enlarged corresponding to a height of an
inner circumferential surface of the cylinder.
[0021] According to still another aspect of the present invention, the rotary compressor
further includes an oil supply passage configured to be stepped between the suction
port of the cylinder and the vane groove.
[0022] As described above, in the rotary compressor according to one embodiment of the present
invention, sealing performance can be improved due to oil and the abrasion of components
can be prevented, so that reliability and compression efficiency of the rotary compressor
can be improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] These and/or other aspects and advantages of the invention will become apparent and
more readily appreciated from the following description of the embodiments, taken
in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic sectional view showing a rotary compressor according to one
embodiment of the present invention;
FIG. 2 is a sectional view showing a compressing unit of the rotary compressor according
to one embodiment of the present invention;
FIG. 3 is a perspective view showing a cylinder of the rotary compressor according
to one embodiment of the present invention;
FIG. 4 is a sectional view taken along line A-A' of FIG. 2;
FIG. 5 is a sectional view showing a compressing unit of a rotary compressor according
to another embodiment of the present invention;
FIG. 6 is a view showing flow of oil in the rotary compressor according to one embodiment
of the present invention; and
FIG. 7 is a view showing a gas leakage passage of a conventional rotary compressor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] Reference will now be made in detail to the embodiments of the present invention,
examples of which are illustrated in the accompanying drawings, wherein like reference
numerals refer to the like elements. The embodiments are described below to explain
the present invention by referring to the figures.
[0025] Hereinafter, preferred embodiments according to the technical feature of a rotary
compressor of the present invention will be described with reference to accompanying
drawings.
[0026] In the following description about the preferred embodiments of the present invention,
a rotary compressor may perform compressing by one compressing unit, but the present
invention is applicable for a twin rotary compressor performing compressing by two
compressing units.
[0027] FIG. 1 is a sectional view schematically showing the structure of the rotary compressor
according to one embodiment of the present invention, and FIG. 2 is a sectional view
showing a compressing unit according to the present invention.
[0028] As shown in FIG. 1, the rotary compressor according to one embodiment of the present
invention includes a case 10 forming an outer portion, a driving unit 30 generating
a driving force, and a compressing unit 50 receiving the driving force of the driving
unit 30 to compress coolant gas. The driving unit 30 and the compressing unit 50 are
installed in the case 10 having a cylindrical shape.
[0029] A suction pipe 11 is connected to one lower side of the case 10 to supply the coolant
gas from an accumulator 70, which processes the liquid-phase coolant, to the compressing
unit 50. A discharge pipe 13 is provided at an upper portion of the case 10 to discharge
the coolant gas compressed in the compressing unit 50. An oil storage space 15 filled
with a predetermined amount of oil is provided at a lower portion of the case 10 in
order to lubricate and cool a member performing friction motion.
[0030] The driving unit 30 includes a stator 31 fixed to the case 10, a rotor 33 rotatably
supported in the stator 31, and a rotating shaft 35 press-fitted into the rotator
33. Accordingly, if power is supplied to the rotor 33, the rotor 33 rotates by electromagnetic
force, and the rotating shaft 35 press-fitted and integrally formed with the rotor
33 transmits rotational force to the compressing unit 50.
[0031] The compressing unit 50 includes an eccentric unit 51 formed at one lower side of
the rotating shaft 35, a roller 52 fitted around the eccentric unit 51, a cylinder
100 provided with a compressing chamber 110 receiving the roller 52, and upper and
lower bearings 53 and 57 coupled to upper and lower portions of the cylinder 100 to
seal the compressing chamber 110 and support the rotating shaft 35.
[0032] The cylinder 100 and the upper and lower bearings 53 and 57 are formed with bolt
coupling holes 101, 54, and 58. As a coupling bolt 59 is inserted into the bolt coupling
holes 101, 54, and 58, the upper and lower bearings 53 and 57 closely make contact
with top and bottom surfaces of the cylinder 100 to seal the compressing chamber 110.
[0033] The cylinder 100 is provided at one side thereof with a suction port 130 connected
to the suction pipe 11 coupled to the accumulator 70 to supply coolant gas, and at
the other side thereof with a discharge port 150 to guide the coolant gas compressed
in the compressing chamber 110 to the outside of the compressing chamber 110.
[0034] A discharge hole 55 is formed at one side of the upper bearing 53 such that the discharge
hole 55 communicates with the discharge port 150 to discharge coolant gas, which has
been guided to the discharge port 150, to an outside. A valve unit 56 is provided
at an upper portion of the upper bearing 53 placed at a side of the discharge hole
55 to open/close the discharge hole 50.
[0035] The mixture of carbon dioxide coolant and oil is introduced into the suction port
130 and supplied to the compressing chamber 110, and the inside of the compressing
chamber 110 is sealed by the oil. The oil supplied to the compressing chamber 110
can be mixed with the carbon oxide coolant to the extent that volumetric efficiency
is not lowered.
[0036] Referring to FIGS. 2 and 3, the suction port 130 is formed through an outer peripheral
surface of the cylinder 100 and an inner peripheral surface of the cylinder 100. An
expansion groove 131 is formed at an outlet of the suction port 130 adjacent to an
inner peripheral surface of the cylinder 100 constituting the compressing chamber
110. The expansion groove 131 can be obtained by enlarging the size of the outlet
of the suction port 130.
[0037] The expansion groove 131 is recessed from the inner circumferential surface of the
cylinder 100 by a predetermined depth, and upper and lower portions of the expansion
groove 131 are open. This is necessary to allow the outlet of the expansion groove
131, which communicates with the compressing chamber 110, to have a height h identical
to a height of an inner surface of the cylinder 100.
[0038] As shown in FIG. 4, oil introduced through the suction port 130 can be sufficiently
supplied to upper and lower portions of the roller 52 as well as a central portion
of an outer circumferential surface of the roller 52 by the expansion groove 131.
[0039] Accordingly, the oil introduced through the suction port 130 is directly supplied
from the outlet of the suction port 130 to the central portion and the upper and lower
portions of the roller 52 due to the structure of the expansion groove 131. Thus,
an oil film is sufficiently formed between an outer circumferential surface of the
roller 52 in the compressing chamber 110 and the inner circumferential surface of
the cylinder 100. Therefore, when compressing high-pressure carbon dioxide coolant,
gas leakage can be prevented from occurring in the longitudinal direction at a region
between the inner circumference surface of the cylinder 100 and the central portion
of the roller 52. That is, the gas is prevented from being leaked from the high-pressure
discharge area 113 of the cylinder 100 to the lower-pressure suction area 111. Accordingly,
volumetric efficiency can be prevented from being lowered due to the gas leakage.
[0040] A vane groove 170 is formed between the suction port 130 and the discharge port 150
of the cylinder 100 and a vane 171 is provided in the vane groove 170. The vane 171
reciprocates relative to the compressing chamber 110 by an elastic port 173 provided
at a rear portion of the vane 171 when the roller 52 rotates in a state in which a
front end of the vane 171 makes contact with the outer circumferential surface of
the roller 52. Thus, an internal space of the compressing chamber 110 is partitioned
into the suction area 111 placed at a side of the suction pipe 11 and the discharge
area 113 placed at a side of the discharge port 150 by the vane 171 so that gas existing
at the inside of the discharge area 113 can be compressed.
[0041] In other words, if the rotating shaft 35 rotates in a direction of a solid line arrow
shown in FIG. 2, the roller 52 eccentrically rotates in the compressing chamber 110,
low-pressure coolant gas, which has been sucked into the compressing chamber 110 through
the suction port 130, is compressed into a high-pressure state in the discharge area
113 of the compressing chamber 110, the size of which is gradually reduced, and discharged
to the discharge port 150.
[0042] During the rotation of the roller 52 along the inner circumferential surface of the
cylinder 100, the vane 171 reciprocates while making contact with the roller 52. High-pressure
coolant gas of the discharge area 113 is introduced into the suction area 111 from
the vane groove 170 due to high pressure difference between the lower-pressure suction
area 111 and the high-pressure discharge area 113.
[0043] In other words, micro-gaps are created at lateral sides of the vane groove 170 and
the vane 171 and at a contact surface between of the roller 52 and the vane 171 to
cause gas leakage.
[0044] Accordingly, in order to prevent the gas leakage, an oil supply passage 190 is formed
between the expansion groove 131 and the vane groove 170 to connect the expansion
groove 131 to the vane groove 170 so that oil can be sufficiently supplied to the
side surface of the vane groove 170 provided at a side the suction area 111 having
high pressure difference. The oil supply passage 190 is necessary to induce oil, which
is introduced through the suction port 130, from the expansion groove 131 to the vane
171.
[0045] As shown in FIG. 3, the oil supply passage 130 according to one embodiment of the
present invention is stepped on top and bottom surfaces of the cylinder 100 such that
the oil introduced through the suction port 130 can be supplied to the side surface
of the vane groove 170 from the upper and lower portions of the expansion groove 131.
[0046] The oil supply passage 190 includes a recess unit 191, which is recessed by a predetermined
depth from the top and bottom surfaces of the cylinder 100 such that a passage is
formed to allow oil to flow from the expansion groove 131 to the vane groove 170 when
the upper and lower bearings 53 and 57 closely make contact with the top and bottom
surfaces of the cylinder 100, and a guide unit 193 guiding the direction of the oil
such that the oil is supplied within a movement range of the vane 171 reciprocating
in the vane groove 170.
[0047] The depth of the recess unit 191 stepped according to one embodiment of the present
invention can be suitably set by taking into compression efficiency consideration,
and may be in the range of about 0.05mm to 0.2mm. Preferably, the depth of the recess
unit 191 is about 0.1 mm.
[0048] The guide unit 193 is inclined in a straight line toward the front end of the vane
groove 170 from one upper side of the expansion groove 131 such that oil is prevented
from being introduced to a rear portion of the vane groove 170 as shown in FIG. 3.
The present invention is not limited thereto, but the guide unit 193 may be formed
in the curved shape as shown in FIG. 5 such that hydraulic resistance of oil can be
reduced.
[0049] Accordingly, oil passing through the suction port 130 is introduced from the upper
and lower portions of the expansion groove 131 to the side surface of the vane groove
170 through the oil supply passage 190, so that oil films are sufficiently formed
on the contact surface of the vane 171 and the vane groove 170, and the contact surface
of the front end of the vane 171 and the roller 52. Accordingly, gas leakage caused
by gap creation is prevented, and components are prevented from being damaged due
to the abrasion of the components in a compression operation.
[0050] Hereinafter, the operation of the rotary compressor having the above structure according
to one embodiment of the present invention and effects according to the operation
of the rotary compressor will be described.
[0051] If a driving force of the driving unit 30 is transmitted so that the rotating shaft
35 rotates, the eccentric unit 51 and the roller 52 coupled to an outer portion of
the eccentric unit 51 eccentrically rotate in the compressing chamber 11, and the
mixture of oil and carbon dioxide coolant that is natural coolant is introduced into
the suction area 111 of the compressing chamber 110 through the suction port 130 according
to the eccentric rotation of the roller 2 as shown in FIG. 6.
[0052] The mixture introduced through the suction port 130 is supplied to upper and lower
portions of the roller 52 as well as the central portion of the roller 52 by the expansion
groove 131 provided at the outlet of the suction port 130 as shown in FIG. 4 so that
oil can be sufficiently supplied to the outer circumferential surface of the roller
52. Accordingly, a sealing area is significantly increased on the contact surface
between the inner circumferential surface of the cylinder 100 and the outer circumferential
surface of the roller 52.
[0053] The mixture introduced into the suction area 111, which is provided in the compressing
chamber 110, is changed into a high-pressure state in the discharge area 113 of the
compressing chamber 110, in which the size of the discharge area 113 is gradually
reduced due to the eccentric rotation motion of the roller 52 and the reciprocation
motion of the vane 171 supported on the outer circumference surface of the roller
52.
[0054] At this time, carbon dioxide coolant having a pressure corresponding to about three
times that of coolant such as R410A is used, so that a gap is created at a contact
surface between components provided in the compressing chamber 110. In particular,
this gap is a main cause of gas leakage from the lateral sides of the vane 171 and
the contact surface between the front end of the vane 171 and the roller 52 representing
the highest pressure difference.
[0055] In this case, oil sucked through the suction port 130 is sufficiently supplied to
the side surface of the vane groove 170 through the oil supply passage 190 formed
between the expansion groove131 and the vane groove 170, so that gas sealing is sufficiently
achieved due to oil.
[0056] In other words, the oil introduced through the suction port 130 is sufficiently uniformly
supplied to a connection part of the roller 52 and the inner circumferential surface
of the cylinder 100 by the expansion groove 131, so that sealing performance of the
compressing chamber110 is improved due to the oil. In addition, since oil is sufficiently
supplied to the side surface of the vane 171 having the highest pressure difference
through the oil supply passage 190, the reliability and the efficiency of the rotary
compressor is remarkably increased when high-pressure carbon dioxide coolant is used.
[0057] As an experimental result for the compressor having a cylindrical shape according
to one embodiment of the present invention, coefficient of performance (COP) and volumetric
efficiency in all operational areas of the compressor can be improved by 20% relative
to a conventional compressor.
[0058] Although few embodiments of the present invention have been shown and described,
it would be appreciated by those skilled in the art that changes may be made in these
embodiments without departing from the principles and spirit of the invention, the
scope of which is defined in the claims and their equivalents.
1. A rotary compressor comprising:
a cylinder comprising a compressing chamber receiving a roller, a suction port supplying
a fluid to the compressing chamber, and a vane groove receiving a vane and allowing
the vane to reciprocate in the vane groove such that the compressing chamber is divided
into a suction area and a discharge area by the vane; and
an expansion groove formed adjacent to an outlet of the suction port and obtained
by enlarging a sectional area of the suction port.
2. The rotary compressor of claim 1, wherein upper and lower portions of the expansion
groove are open.
3. The rotary compressor of claim 1, wherein the cylinder is provided with an oil supply
passage connecting the expansion groove with the vane groove.
4. The rotary compressor of claim 1, wherein the oil supply passage has a stepped portion
on at least one of top and bottom surfaces of the cylinder.
5. The rotary compressor of claim 4, wherein the stepped portion of the oil supply passage
has a height in a range of 0.05 mm to 0.2 mm.
6. The rotary compressor of claim 4, wherein the oil supply passage comprises a guide
unit guiding a direction of oil to one side of a side surface of the vane groove,
and the guide unit is inclined from the expansion groove to a front end of the vane
groove.
7. The rotary compressor of claim 4, wherein the oil supply passage comprises a guide
unit guiding a direction of oil to one side of a side surface of the vane groove,
and the guide unit is curved from the expansion groove to a front end of the vane
groove.
8. The rotary compressor of one of claims 1 to 7, wherein the fluid introduced into the
suction port is mixture of oil and carbon dioxide that is natural coolant.
9. A rotary compressor comprising a cylinder comprising a compressing chamber receiving
a roller, a suction port supplying a fluid to the compressing chamber, and a vane
groove receiving a vane and allowing the vane to reciprocate in the vane groove such
that the compressing chamber is divided into a suction area and a discharge area by
the vane, and wherein the suction port is formed with an outlet having a size identical
to a height of an inner circumferential surface of the cylinder.
10. The rotary compressor of claim 9, further comprising an oil supply passage configured
to be stepped between an expansion groove and the vane groove.
11. A rotary compressor comprising
a cylinder comprising a compressing chamber receiving a roller, a suction port supplying
a fluid to the compressing chamber, and a vane groove receiving a vane and allowing
the vane to reciprocate in the vane groove such that the compressing chamber is divided
into a suction area and a discharge area by the vane, and wherein the suction port
is formed with an outlet enlarged corresponding to a height of an inner circumferential
surface of the cylinder.
12. The rotary compressor of claim 11, further comprising an oil supply passage configured
to be stepped between the suction port of the cylinder and the vane groove.