EP2169230A2

EP2169230A2 - Cylinder and rotary compressor having the same

Info

Publication number: EP2169230A2
Application number: EP08169527A
Authority: EP
Inventors: Yamanaka Masaji; Young Min Choi; Sung Oug Cho
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2008-09-25
Filing date: 2008-11-20
Publication date: 2010-03-31
Also published as: KR20100034914A; EP2169230A3; CN101684812A

Abstract

A rotary compressor includes a cylinder (100) which includes a compressing chamber (110) receiving a roller (52), a suction port (130) supplying a fluid to the compressing chamber (110), and a vane groove (170) receiving a vane (171) and allowing the vane (171) to reciprocate in the vane groove (170) such that the compressing chamber (110) is divided into a suction area (111) and a discharge area (113) by the vane, and an expansion groove (131) formed adjacent to an outlet of the suction port (130) and obtained by enlarging a sectional area of the suction port.

Description

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

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

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.
Under such a circumstance, carbon dioxide (CO₂) is spotlighted as environmental-friendly natural coolant having no problems in relation to toxicity and flammability. Thus, a rotary compressor using such CO₂ as coolant is also spotlighted.
In a rotary compressor using the CO₂ 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 CO₂ 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.
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.
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

Accordingly, it is an aspect of the present invention to provide a rotary compressor capable of improving sealing performance using oil.
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.
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.
According to an aspect of the present invention, upper and lower portions of the expansion groove are open.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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

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

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.
Hereinafter, preferred embodiments according to the technical feature of a rotary compressor of the present invention will be described with reference to accompanying drawings.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.

Claims

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.
The rotary compressor of claim 1, wherein upper and lower portions of the expansion groove are open.
The rotary compressor of claim 1, wherein the cylinder is provided with an oil supply passage connecting the expansion groove with the vane groove.
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.
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.
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.
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.
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.
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.
The rotary compressor of claim 9, further comprising an oil supply passage configured to be stepped between an expansion groove and the vane groove.
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.
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.