Backflow preventing apparatus for compressor

A backflow preventing apparatus for a scroll compressor is disclosed, in which a check valve is hinge-coupled to a valve seat, or is coupled to a valve seat so as to be elastically opened and closed. The check valve is opened and closed by a pressure difference and its own weight or elasticity, thereby having a quick response speed. The check valve prevents discharged refrigerant from backflowing, thus enhancing efficiency of the compressor. Further, since the check valve when opened is prevented from colliding with a valve housing by a valve stopping surface or a retainer, discharge noise from the compressor is reduced.

RELATED APPLICATION

The present application claims priority to Korean Application No. 10-2006-0031625, filed on Apr. 6, 2006, Korean Application No. 10-2006-0081978, filed in Korea on Aug. 28, 2006, and Korean Application No. 10-2007-0016229, filed in Korea on Feb. 15, 2007, all of which are herein expressly incorporated by reference in their entirety.

BACKGROUND

A compressor, and more particularly, a backflow preventing apparatus for a compressor are disclosed herein.

Generally, a compressor serves to compress a refrigerant at a low pressure into a refrigerant at a high pressure. The compressor may include a driving motor that generates a driving force at an inner space of a hermetic casing, and a compression part that compresses a refrigerant using the driving force received from the driving motor. The compressor may be classified into, for example, a reciprocating compressor, a rotary compressor, a scroll compressor, or a centrifugal compressor, according to the method of compressing the refrigerant. However, the compressor may have degraded function or may be damaged when a discharged refrigerant backflows into the inner space of the casing. Accordingly, a backflow preventing apparatus, including a backflow preventing valve is provided to prevent discharged refrigerant from backflowing into the casing. However, the conventional backflow preventing apparatus have various problems.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. The backflow preventing apparatus according to embodiments is shown implemented in both a low pressure type scroll compressor and a high pressure type scroll compressor; however, the backflow preventing apparatus according to embodiments may implemented in other types of compressors as well.

A scroll compressor having a backflow preventing apparatus according to an embodiment will be explained hereinafter. Scroll compressors are widely applied to, for example, air conditioning systems due to their high efficiency and low noise output. A scroll compressor may include a driving motor and a compression part at an inner space of a casing, the compression part including compression chambers formed by two scrolls engaged with each other. In the scroll compressor, a refrigerant is respectively sucked into a pair of compression chambers that are formed by a wrap of an orbiting scroll engaged with a wrap of a fixed scroll. While the refrigerant sucked into the respective compression chambers moves along an orbit of the orbiting scroll, it is compressed and then discharged to the inner space of the casing at a final compression chamber.

FIG. 1discloses a scroll compressor according to one embodiment, which includes a casing10to which a suction pipe11and a discharge pipe12are connected, a main frame20and a sub frame (not shown) fixed to upper and lower sides of an inner circumferential surface of the casing10, a driving motor30with stator31disposed between the main frame20and the sub frame that generates a rotation force, a fixed scroll40fixed to an upper surface of the main frame20and having an involute wrap42at a lower surface of a plate41, an orbiting scroll50having an involute wrap52at an upper surface of a plate51that performs an orbiting motion by being engaged with the involute wrap42of the fixed scroll40so that a plurality of compression chambers are formed, an Oldham's ring60disposed between the orbiting scroll50and the main frame20that orbits the orbiting scroll50while preventing the orbiting scroll50from rotating, a high-low pressure separating plate70coupled to a rear surface of the fixed scroll40that divides an inner space of the casing10into a suction space13and a discharge space14, and a backflow preventing apparatus80disposed at an outlet of the discharge space14that prevents compression gas discharged to the discharge pipe12from backflowing.

In the scroll compressor ofFIG. 1, when power is supplied to the driving motor30, a driving shaft33of the driving motor30is rotated together with a rotor32. Accordingly, the orbiting scroll50performs an eccentric orbiting motion on an upper surface of the main frame20via the Oldham's ring60, thereby forming a pair of compression chambers P that consecutively move between the orbiting wrap52and the fixed wrap42. At the same time, as the orbiting scroll50continuously performs an orbiting motion, a refrigerant is sucked into an outermost compression chamber through an inlet43of the fixed scroll40. While the refrigerant moves to a center of a scroll along an orbit of the orbiting scroll50, it is compressed and is discharged into the discharge space14of the casing10through a discharge port44of the fixed scroll40at the final compression chamber. Then, the refrigerant is discharged, for example, to a condenser of a refrigerating cycle provided in an air conditioning system through the discharge pipe12thus to circulate the refrigerant through the refrigerating cycle.

When the compressor is stopped, a pressure of the discharge space14is lower than that of the discharge pipe12. As a result, the refrigerant discharged to the discharge pipe12may backflow into the discharge space14. However, since a backflow preventing apparatus80is disposed at the outlet of the discharge space14, the refrigerant having been discharged to the discharge pipe12is prevented from backflowing into the discharge space14due to the pressure difference.

Examples of backflow preventing apparatus provided in the outlet of the discharge space have been disclosed, for example, in the U.S. Pat. No. 5,141,420, No. 6,171,084, and No. 6,428,292. The backflow preventing apparatus ofFIG. 1is configured so that a check valve serves to open and close a space between the discharge space and the discharge pipe due to a pressure difference. The backflow preventing apparatus ofFIG. 1will be explained in more detail with reference toFIGS. 2 and 3.

Referring toFIG. 2, the backflow preventing apparatus80includes a housing81having a first refrigerant passing hole85through which the discharge space14and the discharge pipe12of the casing10communicate with one another, and fixedly-coupled to an inner circumferential surface of the casing10; a valve seat82fixedly-coupled to an entrance of the housing81and having a second refrigerant passing hole86at an edge thereof; a stop83fixedly-coupled to an exit of the housing81and having a third refrigerant passing hole87at a center thereof; and a check valve84formed, for example, of a thin plate so as to freely move between the valve seat82and the stop83and having a fourth refrigerant passing hole88at a center thereof, that opens and closes the second refrigerant passing hole86of the valve seat82.

The backflow preventing apparatus80allows a refrigerant to be smoothly discharged and prevents a refrigerant from backflowing by opening and closing the second refrigerant passing hole86of the valve seat82according to an operation state of the compressor. When the compressor is normally operated, since a pressure of the discharge space14is higher than that of the discharge pipe12, the check valve84is pushed to the stop83due to the pressure difference. Since the second refrigerant passing hole86of the valve seat82is opened, the refrigerant discharged to the discharge space14is discharged to the discharge pipe12. However, when the compressor is stopped, since the pressure of the discharge space14is lower than that of the discharge pipe12, the check valve84is pushed to the valve seat82due to the pressure difference. As the second refrigerant passing hole86of the valve seat82is closed, the refrigerant discharged to the discharge pipe12is prevented from backflowing into the discharge pipe14.

Referring toFIG. 3, in the backflow preventing apparatus80, an entrance of the discharge pipe12is stepped without having the housing, the stop, and the valve seat, thereby forming the housing81for receiving the check valve84and the stop83. Also, the valve seat82is formed at an outer surface of the casing10received in the entrance of the discharge pipe12. Herein, the check valve84opens and closes a space between the discharge space14and the discharge pipe12freely moving due to a pressure difference.

However, the backflow preventing apparatus shown inFIG. 1-3has the following problems. Since the check valve84moves only due to the pressure difference, it has a low responsive characteristic and a delayed closing speed. As a result, the refrigerant discharged to the discharge pipe12backflows, and a performance of the compressor is lowered. Further, the check valve84collides with the valve seat82when closed, and collides with the stop83when opened, thereby causing collision noise at the check valve and vibration noise for the compressor.

Hereinafter, a backflow preventing apparatus according to another embodiment will be explained in more detail herein below.

FIGS. 4 to 8Bare views of a backflow preventing apparatus according another embodiment implemented in a scroll compressor. The scroll compressor ofFIG. 4may include a casing100to which a suction pipe110and a discharge pipe120are connected; a main frame200fixed to the inside of the casing100; a driving motor300fixed to the inside of the casing100that generates a driving force; a fixed scroll400fixed to an upper surface of the main frame200; an orbiting scroll500disposed on an upper surface of the main frame200and eccentrically coupled to a driving shaft330of the driving motor300, forming a pair of compression chambers P and performing an orbiting motion by being engaged with the fixed scroll400; an Oldham's ring600disposed between the orbiting scroll500and the main frame200, that causes the orbiting scroll500to orbit while preventing the orbiting scroll500from rotating; a high-low pressure separating plate700that divides an inner space of the casing100into a suction space130and a discharge space140; and a backflow preventing apparatus800inserted into the discharge space140of the casing100, having an entrance connected to the casing100, and having an exit connected to the discharge pipe120, that prevents a refrigerant discharged to the discharge pipe120from backflowing into the discharge space140of the casing100.

The suction pipe110may be connected to the suction space130of the casing100, and the discharge pipe120may be connected to the discharge space140of the casing100. The discharge pipe120may be insertion-coupled to a valve housing810of the backflow preventing apparatus800, thereby connected to the discharge space140.

An involute wrap420of the fixed scroll400and an orbiting wrap520of the orbiting scroll500may be disposed on plates410and510, respectively. The involute wrap420of the fixed scroll400and an orbiting wrap520of the orbiting scroll500may be engaged with each other, thereby forming a pair of compression chambers P that consecutively move. An inlet430through which an outermost compression chamber communicates with the suction space130of the casing100may be disposed at one lower edge of the fixed scroll400. An outlet440with which the discharge space140of the casing100communicates at a final compression chamber may be disposed at a middle portion of the fixed scroll400. A check valve (not shown) that prevents the refrigerant discharged to the discharge space140of the casing100from backflowing into the compression chamber P may be disposed at an exit of the outlet440.

The high-low pressure separating plate700may be formed as a ring-shaped plate having a predetermined width so that an inner circumferential surface thereof may be coupled to an upper surface of the fixed scroll400and an outer circumferential surface thereof may be coupled to the casing100. Reference numeral310denotes a stator,320denotes a rotor, and450denotes a sub frame.

As shown inFIGS. 5 to 7, the backflow preventing apparatus800may include a valve housing810adhered to an inner wall surface of the casing100, a valve seat820fixed to the inside of the valve housing810and having a refrigerant passing hole821at a center thereof, and a check valve830rotatably disposed on the valve seat820so as to open and close the refrigerant passing hole821of the valve seat820by being rotated that prevents a discharged refrigerant from backflowing.

The valve housing810may be disposed in the discharge space140of the casing100, and both ends thereof may be opened so that the discharge space140and the discharge pipe120can may communicate with each other. One of the ends of the valve housing810may have a tapered cylindrical shape to which the discharge pipe120may be connected. The tapered portion may be partially inserted into a through hole101of the casing100, and may be coupled thereto by, for example, welding. The valve housing810may be integrally coupled to the end of the tapered portion so that the valve housing810and discharge pipe120constitute one module. Accordingly, when the valve housing810is coupled to the casing100, the discharge pipe120may be coupled thereto together therewith.

The valve housing810may have a seat supporting portion811that supports the valve seat820. The seat supporting portion811may be formed by being protruded from an inner circumferential surface of the valve housing810, or by contracting both ends of an entrance of the valve housing810.

The valve seat820may have a ring shape having the first refrigerant passing hole821at a center thereof. The valve seat820may be forcibly inserted into the valve housing810, or may be fixed to the valve housing810, such as by welding or a by a bolt. The valve seat820may be integrally formed in the valve housing810.

The valve seat820may have hinge protrusions822for inserting a hinge portion831of the check valve830and rotating the hinge portion831, at right and left upper portions. A side hinge hole823for inserting a hinge pin840may be formed at a center of the hinge protrusion822in correspondence to a side hinge hole833of the check valve830. The side hinge hole823may be formed on the same vertical line as a front end of the valve seat820, or may be disposed at a discharge side so that the check valve830may be smoothly closed by a pressure difference and its weight.

As shown inFIG. 5, a sealing protrusion824may be formed near the refrigerant passing hole821so that a front end of the valve seat820may be in linear contact with a compression surface of the check valve830. However, as shown inFIG. 6, a buffering member825may be disposed so that a refrigerant may be prevented from leaking between the check valve830and the valve seat820when the check valve830is closed, and so that an impact due to collision of the check valve830with another component may be buffered. The buffering member825may be formed to have a circular section so as to be in linear-contact with the check valve830. The buffering member825may be disposed at the compression surface of the check valve830.

As shown inFIGS. 5 to 7, the check valve830may have a hinge portion831configured to be hinge-coupled to the valve seat820at one end thereof, and an opening/closing portion832for opening and closing the refrigerant passing hole821of the valve seat820at another end thereof. The opening/closing portion832may have a disc shape. Further, the check valve830may be formed to be thicker towards the opening/closing portion832from the hinge portion831so as to be quickly opened.

The side hinge hole833may be formed at a center of the hinge portion831in correspondence to the side hinge hole823of the valve seat820. The side hinge hole833may be formed on the same vertical line as the compression surface of the check valve830, or may be disposed at a discharge side so that the check valve830may be smoothly closed by a pressure difference and its weight. The check valve830may have a valve stopping surface834inclined at a certain angle for limiting an opened angle of the check valve830being opened when an outer circumferential surface of the hinge portion831comes into contact with the valve seat820. As shown inFIG. 9, a valve stopping protrusion835for limiting an opened angle of the check valve830by coming into contact with an inner circumferential surface of the valve housing810may be disposed at a compression rear surface of the opening/closing portion832.

The check valve830may be formed of a thin metallic plate with consideration to rigidity and elasticity, or may be formed of an engineered plastic material, such as peek, with consideration to noise and cost.

As shown inFIG. 10, an elastic member850, such as a torsion spring, for accumulating an elastic force when the check valve830is opened and being restored when the check valve830is closed may be installed between the check valve830and the valve seat820. Reference numeral836denotes a spring supporting protrusion. Refrigerant backflow may be effectively prevented by enhancing a closing speed of the check valve830.

Operation and effect of the backflow preventing apparatus according to an embodiment will be explained herein below.

When power is supplied to the driving motor300, the driving shaft330rotates, causing the orbiting scroll500coupled to the driving shaft330to eccentrically orbit by being engaged with the fixed scroll400. When the orbiting scroll500progressively moves within the fixed scroll400, a pair of compression chambers P having decreased volume toward the center of the scrolls is formed. A refrigerant is sucked into the suction space130of the casing100through the suction pipe110, and is sucked to an outermost compression chamber through the outlet430of the fixed scroll400. Then, the refrigerant is compressed while moving towards a final compression chamber, and is discharged into the discharge space140of the casing100. The refrigerant opens the check valve830provided at an entrance of the valve housing810by pushing, moves into the discharge pipe140through the refrigerant passing hole821of the valve seat820, and is discharged from the compressor.

The process for opening and closing the check valve will be explained in detail herein below.

As shown inFIG. 8A, when the compressor is normally operated, a discharge pressure of a refrigerant applied to a front surface of the check valve830is greater than the sum of the pressure applied to a rear surface of the check valve830and the pressure due to the weight of the check valve830. Accordingly, the check valve830is opened by upwardly rotating around the hinge pin840. The refrigerant compressed through the refrigerant passing hole821is quickly discharged to the discharge pipe120. Since the valve stopping surface834having a predetermined inclination angle (α) is formed on an outer circumferential surface of the hinge portion831of the check valve830, it comes into contact with the valve seat820, thereby limiting an opened angle of the check valve830.

In contrast, as shown inFIG. 8B, when the compressor is abnormally operated or stopped, a discharge pressure of a refrigerant applied to the front surface of the check valve830is less than the sum between the pressure applied to the rear surface of the check valve830and the pressure due to the weight of the check valve830. Accordingly, the check valve830is closed by downwardly rotating around the hinge pin840. In this position, the front surface of the check valve830is in linear-contact with the sealing protrusion824of the valve seat820, thereby preventing the refrigerant discharged into the discharge pipe120from backflowing into the discharge space140. As shown inFIG. 6, when the buffering member825is disposed in the valve seat820, the discharge valve830is elastically buffered by the buffering member825. The buffering member825prevents or reduces collision noise or damage to the check valve, and refrigerant backflow is effectively prevented as the buffering member825is in linear-contact with the discharge valve830.

As the check valve is hinge-coupled to the valve seat, the check valve has a quick response speed when opened and closed. When the check valve is closed, it is quickly closed by the pressure difference between both sides thereof and its own weight. Accordingly, discharged refrigerant may be effectively prevented from backflowing, and thus efficiency of the scroll compressor may be enhanced.

Further, collision noise of the check valve may be reduced when the check valve is opened and closed, thereby reducing discharge noise of the compressor. When the check valve is opened, it is prevented from colliding with other components by the valve stopping surface. Also, when the check valve is closed, noise that occurs when the discharge valve collides with the valve seat is reduced by the buffering member provided at the valve seat. Accordingly, discharge noise of the compressor may be reduced.

The backflow preventing apparatus according to another embodiment will be explained herein below.

In the previously disclosed embodiment, the check valve830is implemented as a hinge type valve. However, in this embodiment, the check valve861may be implemented as a read type valve.

The check valve861may be formed of a thin metallic plate having its own elasticity, as shown inFIG. 11. One end of the check valve861may have a fixed end fixedly-coupled to the valve seat820, and another free end for opening and closing the refrigerant passing hole821of the valve seat820by freely rotating centered around the fixed end to a bent state. The check valve861may have an opened degree limited by its own elastic force, by an inner circumferential surface of the valve housing810, or by additionally disposing a retainer862at the rear surface of the check valve830.

Construction and operation of the valve housing810and the valve seat820of the backflow preventing apparatus are the same as those of the aforementioned embodiment, and thus their detailed explanation will be omitted. When the check valve861is opened, noise may be generated as the check valve861collides with the retainer862. However, if the retainer862is formed to have a curved surface in correspondence to an opened shape of the check valve, the collision noise may be reduced.

An installation position of the backflow preventing apparatus according to embodiments may be varied as follows.

As shown inFIG. 12, the valve housing810may be penetratingly-coupled to the casing100, for example, by one or more weldings100a,100b. The valve housing810may be disposed on an outer surface of the casing100, as shown inFIG. 13, or may be insertion-coupled to a discharge plenum900coupled to the fixed scroll410, as shown inFIG. 14.

Referring toFIG. 12, when the valve housing810penetrates the casing100, an outer circumferential surface of the valve housing810penetrates the through hole101of the casing100, and is coupled to the casing by, for example, welding. With this configuration, the backflow preventing apparatus may be assembled even after the casing100is assembled.

Referring toFIG. 13, when the valve housing810is disposed on an outer surface of the casing100, a valve seat portion150having a refrigerant passing hole151may be integrally formed in the casing100. Also, the hinge protrusion152for rotatably coupling the hinge portion831of the check valve830may be disposed above the refrigerant passing hole151. An entrance of the valve housing810receives the check valve830thus to be hermetically-coupled to an outer surface of the casing100, and the discharge pipe120may be connected to an exit of the valve housing810. Since an additional valve seat for fixing the check valve830is not required, the number of components and the number of assembly processes may be reduced. Accordingly, a manufacturing cost may be reduced and productivity enhanced.

Referring toFIG. 14, when the valve housing810is coupled to a discharge plenum900that forms the discharge space, the valve housing810may be insertion-coupled to a through hole910of the discharge plenum900. Also, the discharge pipe120connected to the exit of the valve housing810may be penetratingly-coupled to the casing100sealed to an outer surface of the discharge plenum900. With this configuration, since the inner space of the casing100except the discharge plenum900forms a suction space of low pressure, a welding portion between the casing100and the discharge pipe120may receive less pressure, thus enhancing a sealing force. Also, since the discharge plenum900serves as a muffler, noise from the compressor may be reduced. The valve housing810may be adhered to an inner wall surface of the discharge plenum900.

In the aforementioned embodiment, the backflow preventing apparatus was applied to a low pressure type scroll compressor in which the inner space of the casing is divided into a suction space and a discharge space by the high-low pressure separating plate or the discharge plenum. However, as shown inFIG. 15, the backflow preventing apparatus may be applied to a high pressure type scroll compressor in which the suction pipe110is directly coupled to the fixed scroll400by penetrating the casing100, the inner space of the casing100maintains the discharge space140of a high pressure, and the discharge pipe120is connected to the discharge space140. That is, the backflow preventing apparatus, such as the hinge type valve or the read type valve according to embodiments disclosed herein, is disposed between the discharge space140and the discharge pipe120. Operation of the high-pressure type scroll compressor is the same as that of the low-pressure type scroll compressor, and thus its detailed explanation will be omitted.

Embodiments disclosed herein provide a backflow preventing apparatus for a compressor, such as a scroll compressor, capable of enhancing a performance of the compressor by quickly closing a check valve, enhancing a responsive characteristic of the check valve, and preventing a refrigerant from backflowing.

Embodiments disclosed herein also provide a backflow preventing apparatus for a compressor, such as a scroll compressor, capable of lowering vibration noise of the compressor by reducing collision noise that occurs when the check valve is opened and closed.

The backflow preventing apparatus for a compressor, such as a scroll compressor, includes a valve housing disposed between an inner space of a hermetic casing and a discharge pipe communicated with the inner space, a valve seat disposed at the valve housing and having a refrigerant passing hole so that the inner space of the casing and the discharge pipe can communicate with each other, and a check valve rotatably coupled to the valve seat, that opens and closes the refrigerant passing hole of the valve seat.