CN115143103A

CN115143103A - Compression mechanism

Info

Publication number: CN115143103A
Application number: CN202110340984.8A
Authority: CN
Inventors: 刘轩; 房元灿
Original assignee: Emerson Climate Technologies Suzhou Co Ltd
Current assignee: Copeland Suzhou Co Ltd
Priority date: 2021-03-30
Filing date: 2021-03-30
Publication date: 2022-10-04

Abstract

The present disclosure provides a compression mechanism, comprising: an orbiting scroll including an orbiting scroll end plate and an orbiting wrap formed at one side of the orbiting scroll end plate; the fixed scroll comprises a fixed scroll end plate and a fixed scroll formed on one side of the fixed scroll end plate, and an exhaust port is formed in the fixed scroll end plate; and a valve assembly including a valve sheet including a circular arc-shaped first body portion and a single moving portion extending from the first body portion, the moving portion including a movable end capable of selectively opening or closing the discharge port. According to the present disclosure, it is possible to provide a compressor having a variable volume ratio function which is not limited by an installation space and has a simple structure.

Description

Compression mechanism

Technical Field

The present disclosure relates to the field of scroll compressors, and more particularly, to a compression mechanism of a scroll compressor having a variable volume ratio function.

Background

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

The compressor may be applied to application systems requiring different pressures, such as an air conditioning system, a refrigerator system, etc., and thus, a case where a discharge pressure of a compression chamber (a maximum pressure in the compression chamber) is greater than a pressure required for a specific application system, that is, an over-compression case may occur. In the case of over-compression, the fluid compressed to the discharge pressure will drop to the pressure required by the application system after exiting the compression chambers, and therefore the compressor does unnecessary work, which will reduce the efficiency of the compressor.

In order to reduce or prevent over-compression of the working fluid, compressors having a variable volume ratio function have been developed. The compressor can realize variable volume ratio by using the bypass valve arranged in the auxiliary exhaust port, namely, the compressor can be operated at low volume ratio when the pressure required by the system is low and operated at high volume ratio when the pressure required by the system is high, thereby effectively avoiding over-compression phenomenon and improving the efficiency of the compressor. However, in the field of compressors, there are still technical problems that the variable volume ratio function cannot be realized or the structure for realizing the variable volume ratio function is complicated, leakage is likely to occur, cost is high, and the like, because the installation space is limited and the bypass valve cannot be provided.

Disclosure of Invention

It is an object of one or more embodiments of the present disclosure to provide a compression mechanism of a compressor capable of implementing a variable volume ratio function in a limited installation space in a structurally simple and low-cost manner.

It is another object of one or more embodiments of the present disclosure to provide a compression mechanism of a compressor in which a fastener of a bypass valve can provide a uniform down force to prevent the bypass valve from overturning.

According to an aspect of the present disclosure, there is provided a compression mechanism including: an orbiting scroll including an orbiting scroll end plate and an orbiting wrap formed at one side of the orbiting scroll end plate; a non-orbiting scroll including a non-orbiting scroll end plate having a discharge port formed therein and a non-orbiting scroll formed at one side thereof, the non-orbiting scroll and the orbiting scroll cooperating to form a series of compression chambers therebetween; and a valve assembly characterized by comprising a valve sheet including a circular arc-shaped first body portion and a single moving portion extending from the first body portion, the moving portion including a movable end capable of selectively opening or closing the discharge port.

According to one aspect of the present disclosure, the valve assembly further comprises: a valve stop including a second body portion and a stopper portion extending from the second body portion, the second body portion abutting the first body portion and the stopper portion configured to limit a range of motion of the movable end; and an annular fastener fixed to the non-orbiting scroll and configured to abut against the second body portion to fix axial positions of the valve plate and the valve stop.

According to one aspect of the present disclosure, the valve assembly further includes a positioning pin extending through the pin hole of the valve plate and the pin hole of the valve stopper and into the pin hole of the fixed scroll end plate to prevent circumferential displacement of the valve plate.

According to one aspect of the present disclosure, the exhaust ports include a primary exhaust port in fluid communication with a central compression chamber of the series of compression chambers and a secondary exhaust port in fluid communication with an intermediate compression chamber located radially outward of the central compression chamber, the movable end selectively opening or closing the secondary exhaust port.

According to one aspect of the present disclosure, the intermediate compression chambers include a first intermediate compression chamber and a second intermediate compression chamber, with a fluid passage provided therebetween to allow fluid communication therebetween.

According to an aspect of the present disclosure, the non-orbiting scroll end plate is provided with an annular wall on a side opposite to the fixed wrap, the main discharge port and the sub discharge port are formed in a discharge area defined by the inner annular wall, and the valve assembly is disposed radially inside the inner annular wall.

According to an aspect of the present disclosure, the main discharge port includes a first main discharge port portion and a second main discharge port portion communicating with each other, the first main discharge port portion being located at a center of the non-orbiting scroll end plate and communicating with the central compression chamber, the second main discharge port portion being offset from the first main discharge port portion in a radial direction and communicating with the discharge area.

According to an aspect of the disclosure, the first body portion corresponds to a circumferential angle greater than 180 degrees.

According to an aspect of the present disclosure, the moving portion extends substantially linearly from one end of the first body portion, and a free end of the moving portion forms the movable portion, the free end of the moving portion being close to an imaginary outer circumference defined by the first body portion and/or close to the free end of the first body portion

According to an aspect of the present disclosure, the first body portion has a width smaller than that of the moving portion.

The compressor structure according to the present disclosure can save an installation space of the bypass valve, prevent fluid leakage, and reduce production and processing costs.

Drawings

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

FIG. 1 is a schematic longitudinal cross-sectional view of an exemplary compressor with variable volume ratio functionality;

fig. 2A and 2B are perspective views schematically showing a non-orbiting scroll and a bypass valve of another compressor having a variable volume ratio function;

FIG. 3 is a perspective view schematically illustrating a non-orbiting scroll and a bypass valve of a compressor according to an exemplary embodiment of the present disclosure;

fig. 4 and 5 are a sectional view and a plan view, respectively, schematically illustrating a non-orbiting scroll of a compressor according to an exemplary embodiment of the present disclosure, in which a bypass valve is installed in an inner space of an inner annular wall of the non-orbiting scroll;

FIG. 6 is a top view schematically illustrating a non-orbiting scroll of a compressor according to an exemplary embodiment of the present disclosure with a bypass valve removed;

fig. 7A and 7B are plan views schematically illustrating a valve sheet of a bypass valve of a compressor according to an exemplary embodiment of the present disclosure and a variation thereof;

FIG. 8 is a perspective view schematically illustrating a non-orbiting scroll of a compressor according to an exemplary embodiment of the present disclosure, with a bypass valve removed; and

fig. 9 schematically illustrates a main discharge port arrangement of a compressor according to an embodiment of the present disclosure.

Detailed Description

The following description of the various embodiments of the present disclosure is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. The same reference numerals are used to designate the same components in the respective drawings, and thus the configurations of the same components will not be described repeatedly.

An example compressor having a variable volume ratio will be described with reference to fig. 1. As shown in fig. 1, the compressor 1 may include a housing 20, a driving mechanism, a compression mechanism, a sealing assembly, and a valve assembly.

Specifically, the housing 20 may be constituted by a substantially cylindrical body portion 22, a top cover 24 provided at one end of the body portion 22, and a bottom cover 26 provided at the other end of the body portion 22. A partition plate 30 is provided between the top cover 24 and the body portion 22 to partition the inner space of the housing 20 into the fluid suction chamber 21 and the fluid discharge chamber 23. The space between the partition plate 30 and the top cover 24 constitutes the fluid discharge chamber 23, and the space between the partition plate 30, the body portion 22 and the bottom cover constitutes the fluid suction chamber 21. An intake joint for sucking fluid is provided at one side of the fluid suction chamber 21, and an exhaust joint for discharging compressed fluid is provided at one side of the fluid discharge chamber 23.

A compression mechanism and a drive mechanism for driving the compression mechanism are provided in the housing 20. The compression mechanism sucks fluid from the fluid suction chamber 21 of the housing 20 and discharges the fluid after compression into the fluid discharge chamber 23 of the housing 20. More specifically, referring to fig. 1, the compression mechanism may include, for example, a non-orbiting scroll 40 and an orbiting scroll 50. Orbiting scroll 50 includes an end plate 54 and a spiral orbiting scroll 56 formed on one side of the end plate. The fixed scroll 40 includes an end plate 44 and a spiral fixed scroll 46 formed on one side of the end plate, and the end plate 44 includes a main exhaust port 42 formed at a substantially central position of the end plate and first and second

sub exhaust ports

64 and 66 located radially outside the exhaust port 42. Fixed wrap 46 of fixed scroll 40 and orbiting wrap 56 of orbiting scroll 50 intermesh to define therebetween a series of compression pockets of progressively decreasing volume from the radially outer side to the radially inner side and progressively increasing pressure. Specifically, of the compression chambers, the radially outermost compression chamber has the smallest pressure, the radially innermost compression chamber, i.e., the central compression chamber C1 at the center of the scroll has the largest pressure, and a plurality of intermediate compression chambers located between the radially outermost position and the innermost position have intermediate pressures between the largest pressure and the smallest pressure. Discharge port 42 is in fluid communication with the central compression chamber (the fluid communication described in this section corresponds to direct fluid communication), while first and second

auxiliary discharge ports

64 and 66 are in fluid communication with first and second intermediate compression chambers C2 and C3, respectively, located on either side of the central compression chamber.

To achieve axial sealing between the tip of fixed scroll 46 of fixed scroll 40 and end plate 54 of orbiting scroll 50, and between the tip of orbiting scroll 56 of orbiting scroll 50 and end plate 44 of fixed scroll 40, typically, a back pressure chamber 70 is provided on the opposite side of end plate 44 of fixed scroll 40 from fixed scroll 46. More specifically, an inner annular wall 43 and an outer annular wall 45 are formed on the end plate 44. The inner annular wall 43 defines an exhaust region including the primary exhaust port 42 and the

secondary exhaust ports

64, 66. The back pressure chamber 70 is formed by the space enclosed by the end plate 44, the inner annular wall 43 and the outer annular wall 45 and is closed by a sealing assembly disposed therein which isolates the region of the back pressure chamber at medium pressure from the region of the exhaust gas at high pressure and the region of the suction gas at low pressure. Back pressure chamber 70 is in fluid communication with one of the intermediate pressure chambers between orbiting scroll 50 and non-orbiting scroll 40 through an axially extending through hole (not shown) formed in end plate 44, thereby creating a force that compresses non-orbiting scroll 40 toward orbiting scroll 50, and non-orbiting scroll 40 and orbiting scroll 50 may be effectively pressed together by the pressure in back pressure chamber 70.

Typically, a bypass valve 80 may be provided in the scroll mechanism in order to prevent over-compression of the working fluid. During operation of the compressor 1, working fluid is drawn into the compression mechanism and compressed as it flows from a radially outermost position to a radially innermost position, the compressed fluid is discharged through the main discharge port 42 to a discharge area defined by the inner annular wall 43, and then discharged to the discharge chamber 23 via a one-way valve provided at a central position of the partition plate 30. In the event of over-compression, however, fluid may be prematurely expelled through the secondary exhaust ports to the exhaust region before reaching the radially innermost position. Specifically, when the pressure of the fluid in the compression chambers in the radially intermediate position is greater than the pressure of the fluid in the discharge chambers 23 (i.e., over-compression occurs), the bypass valve selectively opens the

secondary exhaust ports

64, 66, allowing fluid to be discharged prematurely. The bypass valve selectively closes and seals the

secondary exhaust ports

64, 66 when the pressure of the fluid contained in the compression chamber at the radially intermediate position is less than the pressure of the fluid in the discharge chamber 23.

In the compressor 1, in order to enable the back pressure chamber 70 to provide a stable and sufficient pressure to effectively prevent fluid leakage between the respective compression chambers, it is necessary to ensure that the back pressure chamber 70 has a sufficient space, whereby the space inside the annular wall 43 is very limited. In particular, for a small displacement scroll compressor, the space inside the annular wall 43 may have only a diameter of 20mm to 30mm, in which case there is a problem in that it is difficult to fit the bypass valve to the inside of the annular wall 43 to achieve the variable volume ratio function because the volume of the bypass valve is large relative to the scroll.

To address this problem, one way is to use a split bypass valve as shown in fig. 2A and 2B. Fig. 2A and 2B schematically show a fixed scroll and a bypass valve according to another compressor having a variable compression ratio function. The compressor employs a cover plate 220 to divide the discharge area and the back pressure chamber into upper and lower portions so that the installation space of the bypass valve is not limited by the annular wall 43 as in the compressor of fig. 1. Specifically, referring to fig. 2A, non-orbiting scroll end plate 144 and cover plate 220 are fastened together by a plurality of screws 210, wherein non-orbiting scroll end plate 144 is provided with a groove 208 on the opposite side where the wrap is formed, and groove 208 is formed around exhaust port 202 and

sub-exhaust ports

164, 166, thereby forming an exhaust region at groove 208 (i.e., the lower side of cover plate 220).

A corresponding bypass valve 200 is provided in each of the

secondary exhaust ports

164, 166. The bypass valve 200 allows fluid flow from the compression chambers to the exhaust area and prevents fluid flow from the exhaust area to the compression chambers. The bypass valve 200 may include a valve plate 220 covering the

sub-discharge ports

164, 166, a valve stopper 230 preventing the valve plate 220 from being excessively deformed, and a screw 240 fastening the valve plate 220 and the valve stopper 230 to the non-orbiting scroll. The valve sheet 220 has a movable portion 226 and a fixed portion 224, the movable portion 226 being displaceable between an open position and a closed position relative to the fixed portion 224. The screw 240 extends through the valve plate 220 and the valve stop 230 and is fixed into a valve fixing hole formed in the non-orbiting scroll end plate 144, thereby limiting the axial and circumferential positions of the valve plate 220 and the valve stop 230.

The upper side of the cover plate 220 forms a recess 222, the recess 222 being in fluid communication with an intermediate pressure chamber in the compression chambers through an intermediate pressure bore, and a seal assembly may be disposed in the recess 222 to form a back pressure chamber that provides an axial sealing force to the non-orbiting scroll. A spacer 250 is disposed between cover plate 220 and non-orbiting scroll end plate 144.

However, in the split type compressor shown in fig. 2A and 2B, the non-orbiting scroll is divided into upper and lower two layers due to the presence of the upper cover plate, and the overall height of the non-orbiting scroll is increased, thereby correspondingly increasing the height and volume of the compressor, resulting in an increase in the production cost of the compressor. Furthermore, since the discharge area between the cover plate 220 and the non-orbiting scroll end plate 144 has a large pressure, there is a risk that the screw-coupled cover plate 220 and the non-orbiting scroll end plate 144 may not be completely sealed and fluid leakage may occur, thereby possibly resulting in a reduction in performance of the compressor. And this makes the structure complicated and increases the production and processing costs due to the need to use additional cover plates 220, gaskets 250, and corresponding fasteners.

In order to solve the above problems, the present inventors have devised an improved compressor structure capable of not only saving the installation space required for the bypass valve but also preventing fluid leakage and reducing the production and processing costs.

A compressor according to an exemplary embodiment of the present disclosure will be described in further detail with reference to fig. 3 to 8, in which like reference numerals denote like components and detailed descriptions thereof will be omitted.

The compressor according to the exemplary embodiment of the present disclosure is substantially similar in structure to the compressor of fig. 1, except that the non-orbiting scroll 40A of the compressor according to the present disclosure is provided with one bypass hole 64 and a bypass valve 100 is provided in the annular wall 43 of the non-orbiting scroll 40A. As shown in FIG. 3, the bypass valve 100 may include a valve plate 120. The valve sheet 120 includes a first body portion 122 having a circular arc shape and a single moving portion 124 extending from the first body portion 122, and the moving portion 124 includes a movable end 126 capable of selectively opening or closing the sub-exhaust port 64 (shown in fig. 4 and 6). Still referring to FIG. 3, the bypass valve 100 may also include a valve stop 140 and an annular fastener 180. The valve stopper 140 corresponds to the valve plate 120 and includes a second body 142 having a circular arc shape and a stopper 144 extending from the second body 142. In the assembled state, the second body portion 142 abuts against the first body portion 122 and the stopper portion 144 is formed with an inclined surface to limit the maximum movement range of the movable end 126. An annular fastener 180 is fixed to the inner annular wall 43 of the non-orbiting scroll 40A and is configured to abut against the second body portion to limit the axial position of the valve plate 120 and the valve stop 140. The fastening force of the annular fastener 180 is applied to the second body portion 142 of the valve stopper 140 and the first body portion 122 of the valve sheet 120, so that the second body portion 142 abuts against the entirety of the first body portion 122 and the entirety of the first body portion 122 is kept fixed. Such an annular fastener can provide uniform downforce and prevent tipping of the bypass valve 100.

The annular fastener 180 may be removably attached to the internal threads of the inner annular wall 43, such as by a threaded connection, to removably secure the bypass valve 100 radially inward of the inner annular wall 43. The annular fastener 180 may also be formed with two notches 182 that are symmetrically arranged so that the annular fastener 180 can be easily secured or detached from the annular wall 43 using a tool, facilitating installation and maintenance of the bypass valve 100.

The bypass valve 100 may further include a positioning pin 160, the positioning pin 160 extending through the pin holes 123,125 of the valve plate 120 and the pin holes 143, 145 of the valve stop 140 and to the non-orbiting pin holes 46, 48 (shown in FIG. 6) to prevent circumferential displacement of the valve plate 120. The two pin holes 123,125 of the valve plate 120 are respectively disposed at the boundary portion of the first body portion and the moving portion and at the portion of the first body portion between the boundary portion and the free end of the first body portion. The pin holes 143, 145 of the valve stopper 140 and the screw pin holes 46, 48 may be arranged corresponding to the two pin holes 123,125 of the valve plate 120.

The bypass valve 100 according to the present disclosure includes only a single moving part 124, which requires only a small installation space and thus can be installed in a small displacement compressor, thereby implementing a variable compression ratio function. In addition, the compressor according to the exemplary embodiment of the present disclosure may avoid the use of an additional cover plate, a gasket, and a corresponding fastener, reduce manufacturing costs and component costs, and prevent fluid leakage from a high pressure discharge region between the cover plate and the non-orbiting scroll end plate, as compared to the split type compressor shown in fig. 2A and 2B. Also, the compressor structure according to the exemplary embodiment of the present disclosure has high compatibility, is applicable to most scrolls, and can maintain the size of the existing compressor outer shape structure.

In addition, since the annular fastener 180 may uniformly apply a downward fastening force to the circular arc-shaped second body part 142 of the valve stopper 140 and the circular arc-shaped first body part 122 of the valve plate 120 on the circumference thereof, the fastener 180 may firmly fasten the valve stopper 140 and the valve plate 120 into the non-orbiting scroll. Compared with a bypass valve using screws as fasteners, such as shown in fig. 2, the annular fastener 180 changes from point stress to annular surface stress by uniformly distributing the pressing force along almost the entire annular body portion, thereby effectively preventing stress concentration, extending the service life of the bypass valve, and also enabling the bypass valve to be more firmly and stably held in the non-orbiting scroll.

Fig. 7A and 7B show the valve sheet 120 and a modification 120A thereof, respectively. Referring to fig. 7A, the circular arc-shaped first body portion 122 may preferably correspond to a circumferential angle greater than 180 ° (i.e., an arc length greater than a semicircle). In this way, on the one hand, the annular fastening member 180 can have a sufficiently large area of action on the valve plate 120 for providing a uniform pressing force, and on the other hand, the longer circular arc-shaped body portion can have a large empty space inside thereof so as to avoid the main discharge port 42. More preferably, the first body portion 122 may preferably have a circumferential angle corresponding to 220 °. In addition, the width of the first body part 122 may be smaller than the width of the moving part 124. The wider moving portion 124 ensures that the moving portion maintains sufficient strength to prevent fracture failure during repeated up and down movement of the movable end 126, while the thinner body portion 122 ensures that sufficient space is provided for the main exhaust port 42 to prevent interference with the main exhaust port's fluid discharge.

Although FIG. 2 schematically illustrates the presence of two locating pins 160, those skilled in the art will appreciate that the bypass valve 100 may include only one locating pin 160. Fig. 7B shows the valve plate 120A structure in the case where the bypass valve 100 includes only one positioning pin 160. Referring to fig. 7B, the pin hole 125 of the valve sheet 120A may be disposed at an interface of the first body part 122 and the moving part 124. Accordingly, the number of the first and second electrodes, the pin holes 145 and the pin holes 48 in the non-orbiting scroll end plate may be arranged corresponding to the pin holes 125. When the moving part 124 moves relative to the first body part 122, the valve sheet 120A may be effectively prevented from being circumferentially displaced by the positioning pin 160 extending through the pin hole 125 at the interface, and in particular, the valve sheet 120A may be prevented from being circumferentially displaced by the single positioning pin 160 and the arc-shaped first body part 122. As shown in fig. 7A and 7B, the moving portion 124 extends substantially linearly from one end of the first body portion 122, and a free end of the moving portion forms the movable end 126, the free end of the moving portion 235 being proximate to the imaginary outer circumference defined by the first body portion 122 and/or proximate to the free end of the first body portion 122.

Preferably, in the compressor according to the exemplary embodiment of the present disclosure, a fluid passage may be provided between the first intermediate compression chamber C2 and the second intermediate compression chamber C3 to communicate therewith. FIG. 8 illustrates an exemplary non-orbiting scroll provided with a fluid passage according to the present disclosure, wherein the bypass valve 100 is not shown. The second intermediate compression chamber C3 may be symmetrical to the first intermediate compression chamber C2 about the central compression chamber C1. A fluid passage 300 including

sections

310, 320, and 330 may be disposed between the first intermediate compression chamber C2 and the second intermediate compression chamber C3. In the description of this application, will have the middle compression chamber of roughly the same pressure and cavity volume in the working process of compressor and be called a set of first middle compression chamber and second middle compression chamber, a set of middle compression chamber is carminative simultaneously to avoid the excessive compression or the under-compression of a certain compression chamber that the not simultaneously carminative arouses, improve the performance of compressor. In a symmetrical single-scroll compressor, the compression chambers are symmetrical with respect to the central compression chamber, and the pressures and volumes in the two symmetrical compression chambers are substantially the same and can be regarded as a set of intermediate compression chambers. In a twin-scroll compressor, there may be two sets (i.e., four) of intermediate compression chambers of approximately the same pressure and volume. In the asymmetric scroll design, the compression pockets formed by the fixed and orbiting scrolls are asymmetric with respect to the central compression pocket, and thus, the first intermediate compression pocket C2 may also be asymmetric with respect to the second intermediate compression pocket C3. Since a fluid passage is provided between the first intermediate compression chamber C2 and the second intermediate compression chamber C3, it is possible to simultaneously discharge the fluid of the intermediate compression chambers located at the same pressure through the single secondary discharge port 64 and the bypass valve 100 in advance, further improving the performance of the compressor.

Furthermore, the exhaust port 42 is typically centrally located in the end plate 44 of the non-orbiting scroll 40, and in the case of a very limited space defined by the inner annular wall 43, such a centrally located exhaust port may interfere with the provision of the bypass valve such that the bypass valve extends at least partially across the main exhaust port 42, which may cause high pressure fluid discharged through the main exhaust port 42 to act on the flaps of the bypass valve, possibly causing the bypass valve to prematurely discharge the under-compressed fluid without over-compression. In order to solve the above-mentioned problem, referring to fig. 8, in one embodiment according to the present disclosure, the main exhaust port 42A of the non-orbiting scroll 40A includes a first exhaust port portion 42A and a second exhaust port portion 420B communicating with each other. First discharge port portion 420A is centrally located in end plate 44 of non-orbiting scroll 40A and is in fluid communication with central compression chamber C1, and second discharge port portion 420B is offset in a radial direction from first discharge port portion 42A and is in fluid communication with a discharge region defined by inner annular wall 43. In the compressor according to the present disclosure, since the second exhaust port portion 420B located axially upward is offset from the first exhaust port portion 420A located centrally of the end plate below, interference of the exhaust port 42A with the bypass valve 100 is reduced, and a larger installation space is provided for the bypass valve 100.

Although various embodiments and modifications of the present disclosure have been specifically described above, it will be understood by those skilled in the art that the present disclosure is not limited to the specific embodiments and modifications described above but may include other various possible combinations and combinations. Other modifications and variations may be effected by one skilled in the art without departing from the spirit and scope of the disclosure. All such variations and modifications are intended to fall within the scope of the present disclosure. Moreover, all the components described herein may be replaced by other technically equivalent components.

Claims

1. A compression mechanism, comprising:

an orbiting scroll (50) including an orbiting scroll end plate (54) and an orbiting wrap (56) formed on one side of the orbiting scroll end plate;

a non-orbiting scroll (40A) including a non-orbiting scroll end plate (44) having a discharge port (42, 64) formed therein and a non-orbiting wrap (46) formed on one side of the non-orbiting scroll end plate, the non-orbiting and orbiting scrolls cooperating to form a series of compression chambers therebetween; and

valve assembly (100), characterized in that it comprises:

a valve flap (120, 120A) comprising a first body portion (122) of circular arc shape and a single moving portion (124) extending from the first body portion, the moving portion comprising a movable end (126) capable of selectively opening or closing the exhaust port.

2. The compression mechanism of claim 1, wherein the valve assembly (100) further comprises:

a valve stop (140) comprising a second body portion (142) and a stop portion (144) extending from the second body portion, the second body portion abutting the first body portion and the stop portion configured to limit a range of motion of the movable end; and

an annular fastener (180) secured to the non-orbiting scroll (40A) and configured to abut the second body portion to fix an axial position of the valve plate and the valve stop.

3. The compression mechanism of claim 2, further comprising a locating pin (160) extending through the pin hole (123, 125) of the valve plate and the pin hole (143, 145) of the valve stop and into the pin hole (46, 48) of the non-orbiting scroll end plate (44) to prevent circumferential displacement of the valve plate.

4. The compression mechanism as recited in any one of claims 1-3, wherein the exhaust ports include a primary exhaust port (42) and a secondary exhaust port (64), the primary exhaust port being in fluid communication with a central compression chamber (C1) of the series of compression chambers and the secondary exhaust port being in fluid communication with an intermediate compression chamber (C2) of the series of compression chambers radially outward of the central compression chamber, the movable end (126) selectively opening or closing the secondary exhaust port (64).

5. The compression mechanism according to claim 4, wherein the intermediate compression chamber includes a first intermediate compression chamber (C2) and a second intermediate compression chamber (C3), and a fluid passage (300) for fluid communication is provided between the first intermediate compression chamber (C2) and the second intermediate compression chamber (C3).

6. The compression mechanism of claim 4, wherein the non-orbiting scroll end plate is provided with an annular wall (43) on a side opposite the non-orbiting scroll, the primary and secondary discharge ports are formed in a discharge area defined by the inner annular wall, and the valve assembly (100) is disposed radially inward of the inner annular wall.

7. The compression mechanism of claim 6, wherein the primary discharge port (42A) includes a first primary discharge port portion (420A) and a second primary discharge port portion (420B) in communication with each other, the first primary discharge port portion being centrally located in the non-orbiting scroll end plate and communicating with the central compression chamber, the second primary discharge port portion being offset in a radial direction from the first primary discharge port portion and communicating with the discharge region.

8. The compression mechanism of any of claims 1-3, wherein the first body portion (122) corresponds to a circumferential angle greater than 180 degrees.

9. The compression mechanism according to any one of claims 1 to 3, wherein the moving portion (124) extends substantially linearly from one end of the first body portion (122) and a free end of the moving portion forms the movable end (126), the free end of the moving portion being close to an imaginary outer circumference defined by the first body portion and/or close to the free end of the first body portion.

10. The compression mechanism according to any one of claims 1 to 3, wherein a width of the first body portion (122) is smaller than a width of the moving portion (124).