CO2 scroll compressor intermediate exhaust hole and design method thereof

Abstract

The application discloses a CO2 scroll compressor intermediate exhaust hole and a design method thereof, which comprises a first intermediate exhaust hole and a second intermediate exhaust hole, the first intermediate exhaust hole and the second intermediate exhaust hole are symmetrically distributed about the center of a static scroll base circle, the center of the first intermediate exhaust hole is parallel to a tangent of the static scroll base circle, and the center of the second intermediate exhaust hole is parallel to the tangent of the static scroll base circle. The application can ensure the uniformity of the pressure of symmetrical working cavities without increasing the invalid volume of the scroll compressor, improve the energy efficiency ratio of the scroll compressor operation, avoid the non-uniformity of the pressure of symmetrical working cavities of the scroll compressor during operation, reduce the mechanical stress concentration and vibration caused by the non-uniform pressure, and thus enhance the stability of the CO2 scroll compressor operation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of fluid machinery and vehicle CO2 thermal management system, and particularly relates to a middle exhaust hole of a CO2 scroll compressor and a design method thereof. BACKGROUND

[0002] Scroll compressors have the characteristics of high efficiency, low noise and smooth operation, and are widely used in various air conditioning and heat pump systems. In particular, in vehicle CO2 thermal management systems, scroll compressors are the preferred compressor solution. There are two symmetrical working chambers in the scroll compressor to compress gas together, but factors such as changes in operating conditions and design of exhaust holes can cause pressure inconsistencies between the two symmetrical working chambers. This pressure inconsistency can adversely affect the stable operation of the scroll compressor and increase the impact on the motor. In particular, for vehicle CO2 thermal management systems, the refrigeration heat pump cycle therein often operates in the transcritical range, and its operating characteristics are high operating pressure and large pressure difference borne by the scroll compressor, so the pressure uniformity of the symmetrical working chambers of the scroll compressor is particularly important. Reasonable design of the middle exhaust hole is the key to ensuring stable and efficient operation of the CO2 scroll compressor.

[0003] There are currently two main solutions to the problem of pressure non-uniformity in the symmetrical working chambers of scroll compressors. One is to cut a groove at the beginning of the dynamic scroll or the static scroll to connect the two working chambers in advance. The second is to set up a middle exhaust hole to allow the two working chambers to exhaust simultaneously and in advance. Although the scroll compressor using the first solution can effectively reduce the non-uniformity of the symmetrical working chambers, it will increase the invalid volume of the scroll compressor, thereby reducing the efficiency of the scroll compressor. The existing scroll compressor using the second solution generally only focuses on the symmetrical distribution of the two middle exhaust holes about the center of the base circle of the static scroll, and this design can only ensure that the two working chambers start to exhaust at the same time. In fact, the specific position of the middle exhaust hole also has a great influence on the uniformity of the pressure in the symmetrical working chambers. When the middle exhaust hole is completely blocked by the static scroll before the beginning of the dynamic scroll and the static scroll is disengaged, neither of the two working chambers can exhaust through the middle exhaust hole. At this time, if one of the working chambers is connected to the main exhaust hole first, it will cause pressure non-uniformity in the symmetrical working chambers. Therefore, reasonable design of the middle exhaust hole is of great significance to ensure the stable operation of the scroll compressor. SUMMARY

[0004] The purpose of the present application is to provide a middle exhaust hole of a CO2 scroll compressor and a design method thereof, which solves the problem of pressure non-uniformity in the symmetrical working chambers of the scroll compressor in the prior art.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0006] A CO2 scroll compressor intermediate exhaust hole, comprising a first intermediate exhaust hole and a second intermediate exhaust hole, the first intermediate exhaust hole and the second intermediate exhaust hole are symmetrically distributed about the center of the static scroll base circle, the center of the first intermediate exhaust hole is parallel to the tangent of the static scroll base circle and the center of the second intermediate exhaust hole is parallel to the tangent of the static scroll base circle.

[0007] Further, the angle between the center of the first intermediate exhaust hole and the tangent of the static scroll base circle and the static scroll x-axis is in the range of (-π, π).

[0008] Further, the first intermediate exhaust hole is tangent to the static scroll inside involute, the center of the first intermediate exhaust hole is located on the generating line of the involute at the tangent point, and the generating line is tangent to the static scroll base circle.

[0009] Further, the second intermediate exhaust hole is tangent to the static scroll outside involute, the center of the second intermediate exhaust hole is located on the generating line of the involute at the tangent point, and the generating line is tangent to the static scroll base circle.

[0010] A design method of the CO2 scroll compressor intermediate exhaust hole, comprising:

[0011] According to the position relationship between the static scroll base circle and the intermediate exhaust hole, the center and the radius of the intermediate exhaust hole are determined;

[0012] The center position of the intermediate exhaust hole is corrected, and the position and size of the intermediate exhaust hole are determined according to the corrected center and radius.

[0013] Further, for the static scroll with a fixed base circle, the center coordinates of the first intermediate exhaust hole are:

[0014]

[0015] Wherein, x B and y B respectively represent the horizontal and vertical coordinates of the center of the first intermediate exhaust hole, a represents the radius of the base circle, α represents the starting angle of the involute, θ represents the angle between the tangent of the center of the first intermediate exhaust hole and the static scroll base circle and the static scroll x-axis, and r1 represents the radius of the first intermediate exhaust hole;

[0016] The center coordinates of the second intermediate exhaust hole are:

[0017]

[0018] Wherein, x F and y F respectively represent the horizontal and vertical coordinates of the center of the second intermediate exhaust hole, and r2 represents the radius of the second intermediate exhaust hole.

[0019] Further, for the variable-diameter base circle of the static vortex disc, the method for determining the center of the intermediate exhaust hole is:

[0020] According to the involute of the variable base circle radius, the base circle radius is determined, the curvature radius of the outer side profile line is obtained, and the outer side profile line equation is constructed;

[0021] According to the spread angle of the inner side profile line, the curvature radius of the inner side profile line is determined, and the inner side profile line equation is constructed;

[0022] Based on the outer side profile line equation and the inner side profile line equation, the center coordinates of the first intermediate exhaust hole and the second intermediate exhaust hole are determined.

[0023] Further, the base circle radius is

[0024] a(φ)=a0+δ0φ k

[0025] wherein a0 represents the initial radius of the base circle, δ0 represents a parameter for controlling the rate of change of the base circle radius with the angle, φ represents the angle of spread, and k represents a parameter for controlling the nonlinear influence of φ on the base circle radius;

[0026] The curvature radius of the outer side profile line is

[0027]

[0028] The outer side profile line equation is:

[0029]

[0030] The spread angle of the inner side profile line is

[0031] φ in =φ+π-α in -α out

[0032] wherein α in represents the initial angle of the inner involute, and α out represents the initial angle of the outer involute;

[0033] The curvature radius of the inner side profile line is

[0034]

[0035] The inner side profile line equation is:

[0036]

[0037] Further, the center coordinates of the first intermediate exhaust hole are:

[0038]

[0039] The center coordinates of the second intermediate exhaust hole are:

[0040]

[0041] Further, the correction method includes symmetric arc correction and symmetric arc plus straight line correction, and the corrected scroll compressor has a connection arc correction angle, and the angle between the tangent of the center of the first intermediate exhaust hole and the static scroll base circle and the x-axis of the static scroll is less than the connection arc correction angle.

[0042] Compared with the prior art, the present application has the following beneficial effects:

[0043] The present application provides a CO2 scroll compressor intermediate exhaust hole, which is designed for a CO2 thermal management system scroll compressor for vehicles. By optimizing the position of the intermediate exhaust hole, the first intermediate exhaust hole and the second intermediate exhaust hole are symmetrically distributed about the center of the static scroll base circle, and the tangent of the center of the first intermediate exhaust hole and the tangent of the center of the second intermediate exhaust hole are parallel to the tangent of the static scroll base circle. This design avoids the non-uniformity of the pressure in the symmetric working cavity of the scroll compressor during operation, reduces the mechanical stress concentration and vibration caused by uneven pressure, and ensures the balance of forces on each part of the scroll compressor during operation, thereby reducing mechanical wear and failure caused by uneven forces and enhancing the stability of the scroll compressor, especially the CO2 scroll compressor. By maintaining the consistency of the pressure in the symmetric working cavity, the internal fluid dynamics of the scroll compressor are optimized, which helps to reduce energy loss during compression, improve compression efficiency, and make the flow of gas in the scroll compressor smoother, thereby reducing energy consumption caused by flow resistance and improving the overall performance of the scroll compressor. Compared with the prior art, the present application can ensure the consistency of the pressure in the symmetric working cavity without increasing the invalid volume of the scroll compressor, thereby improving the energy efficiency ratio of the scroll compressor during operation. Under the same input power, the scroll compressor can output more useful work, or consume less power when outputting the same useful work, which is of great significance for improving energy utilization efficiency and reducing operating costs. The present application has wide applicability and potential market value in fields that require high stability and high efficiency, such as new energy vehicles and cold chain logistics, and can promote the development and progress of related industries. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be considered as limiting the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0045] Figure 1 The geometric relationship diagram corresponding to the engagement point when the initial end of the dynamic scroll and the static scroll of the scroll compressor of the present application using the equal wall thickness profile modified by symmetric circular arcs is disengaged.

[0046] Figure 2 The geometric relationship diagram corresponding to the engagement point when the initial end of the dynamic scroll and the static scroll of the scroll compressor of the present application using the variable wall thickness profile modified by symmetric circular arcs is disengaged. DETAILED DESCRIPTION

[0047] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0049] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0050] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of the present application is used, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0051] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly inclined. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0052] In the description of the embodiments of the present application, it also needs to be explained that, unless otherwise explicitly specified and limited, if the terms "arrange", "install", "connect", "connect" appear, they should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or indirectly connected through an intermediate medium, it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0053] The present application will be further described in detail below in combination with the drawings:

[0054] The present application provides a CO2 scroll compressor intermediate exhaust hole, comprising a first intermediate exhaust hole and a second intermediate exhaust hole. The first intermediate exhaust hole and the second intermediate exhaust hole are symmetrically distributed about the center of the static scroll base circle, and the center of the first intermediate exhaust hole is parallel to the tangent of the static scroll base circle and the center of the second intermediate exhaust hole is parallel to the tangent of the static scroll base circle. This design ensures that the pressure distribution of each working cavity inside the scroll compressor is more uniform during operation, which can effectively avoid the non-uniformity of the pressure of the symmetric working cavity of the scroll compressor, and help to reduce the mechanical stress concentration and vibration caused by uneven pressure.

[0055] The angle θ between the tangent of the center of the first intermediate exhaust hole and the static scroll x-axis and the static scroll base circle is in the range of (-π, π), which is beneficial to optimize the gas flow path, improve the exhaust efficiency, and reduce energy consumption and noise. The first intermediate exhaust hole is tangent to the involute on the inside of the static scroll, the center of the first intermediate exhaust hole is located on the generating line of the involute at the tangent point, and the generating line is tangent to the static scroll base circle. The second intermediate exhaust hole is tangent to the involute on the outside of the static scroll, the center of the second intermediate exhaust hole is located on the generating line of the involute at the tangent point, and the generating line is tangent to the static scroll base circle. The first intermediate exhaust hole and the second intermediate exhaust hole are tangent to the involute on the inside and outside of the static scroll, respectively, which helps to reduce the flow resistance of the gas during the exhaust process, because the gas can smoothly flow out along the natural curve of the involute without generating excessive turbulence or pressure loss. By precisely controlling the center position of the exhaust hole and the tangent relationship with the involute, it can ensure that the gas can be quickly and effectively discharged from the scroll compressor when needed. This helps to improve the exhaust efficiency of the overall equipment, reduce energy consumption, and also helps to disperse stress, reduce vibration and noise caused by gas discharge, thereby enhancing the structural stability of the entire scroll compressor and prolonging the service life of the equipment.

[0056] The present application also provides a design method of a CO2 scroll compressor intermediate exhaust hole, comprising the following steps:

[0057] According to the positional relationship between the static scroll base circle and the intermediate exhaust hole, the center and radius of the intermediate exhaust hole are determined;

[0058] The center position of the intermediate exhaust hole is corrected, and the position and size of the intermediate exhaust hole are determined according to the corrected center and radius.

[0059] The design method of the present application accurately determines the center and radius of the intermediate exhaust hole according to the positional relationship between the static volute base circle and the intermediate exhaust hole, ensuring the accuracy of the exhaust hole design. The method includes correction of the center position of the intermediate exhaust hole, which helps to further optimize the position and size of the exhaust hole, thereby improving the compression efficiency and exhaust capacity of the scroll compressor. By accurately controlling the position and size of the exhaust hole, energy loss during compression can be reduced, and overall efficiency can be improved.

[0060] wherein, for the static volute of the fixed base circle, the center coordinates of the first and second intermediate exhaust holes are determined according to the involute of the circle;

[0061] The method is not only suitable for the static volute of the fixed base circle, but also suitable for the static volute of the variable base circle. By constructing the outer and inner profile line equations, the center coordinates of the exhaust hole under different base circle radii can be accurately determined, thereby improving the versatility and flexibility of the design method.

[0062] For the static volute of the variable base circle, the base circle radius is determined according to the involute of the variable base circle radius, the curvature radius of the outer profile line is obtained, and the outer profile line equation is constructed;

[0063] The curvature radius of the inner profile line is determined according to the inner profile line spread angle, and the inner profile line equation is constructed;

[0064] The center coordinates of the first and second intermediate exhaust holes are determined based on the outer and inner profile line equations.

[0065] Embodiment 1:

[0066] This embodiment provides a CO2 scroll compressor intermediate exhaust hole as shown in Figure 1 is a schematic diagram of a scroll compressor with equal wall thickness profile using symmetric arc correction. The first and second intermediate exhaust holes are symmetrically distributed relative to the static volute base circle, i.e. the centers of the two intermediate exhaust holes are parallel to the tangent BC and DF of the base circle. This arrangement can ensure that the two intermediate exhaust holes open and close at the same time, thereby ensuring the uniformity of the symmetric working chamber pressure.

[0067] At the moment shown in Figure 1 , the dynamic volute and the static volute are at the moment before disengagement, i.e. the two symmetric working chambers are about to merge into the center chamber, becoming a new chamber. At this moment, the first intermediate exhaust hole and the inner profile line of the static volute are tangent to point A, the second intermediate exhaust hole and the outer profile line of the static volute are tangent to point E, and points A and E are also the engagement points of the dynamic volute and the static volute.

[0068] In this embodiment, the design method of the intermediate exhaust hole in the CO2 scroll compressor is as follows:

[0069] The angle between the tangent BC of the base circle of the static scroll and the x-axis of the static scroll is θ, and the counterclockwise direction is the positive direction of θ, and the value range of θ is (-π, π).

[0070] The length of the generating line of the involute of a circle can be determined according to the geometric parameters of the profile:

[0071] ρ=aφ

[0072] The first intermediate exhaust hole is tangent to the involute on the inside of the static scroll at point A, the center B of the circle is located on the generating line of the involute at point A, the radius is r1, and the generating line is tangent to the base circle of the static scroll at point C. The second intermediate exhaust hole is tangent to the involute on the outside of the static scroll at point E, the center F of the circle is located on the generating line of the involute at point E, the radius is r2, and the generating line is tangent to the base circle of the static scroll at point D.

[0073] According to the definition of the involute of a circle, the lengths of straight lines AC and DE are:

[0074]

[0075] Wherein, a represents the base circle radius, and a represents the involute starting angle.

[0076] Then the coordinates (x B ,y B ) of point B and the coordinates (x F ,y F ) of point F are:

[0077]

[0078] The use of equal wall thickness profile design can reduce the friction loss of the scroll compressor during operation and improve the compression efficiency. Through the correction of the involute of a circle, the contact position between the exhaust hole and the scroll plate can be accurately controlled to ensure that the exhaust hole opens and closes at the right time, avoiding gas leakage and energy loss. For the equal wall thickness scroll compressor with symmetric circular arc correction and symmetric circular arc plus straight line correction, there is a connection circular arc correction angle γ, and only when θ<γ, the first intermediate exhaust hole and the second intermediate exhaust hole can still be connected with the symmetric working cavity for a period of time after the initial end of the dynamic scroll and the static scroll is disengaged, thereby ensuring the uniformity of the pressure of the symmetric working cavity. Therefore, the design of the intermediate exhaust hole of the equal wall thickness scroll compressor with symmetric circular arc plus straight line correction also needs to follow the rule of θ<γ.

[0079] It should be noted that the connection arc correction angle of the equal wall thickness scroll compressor using symmetric arc correction and symmetric arc plus straight line correction may be γ < 0. Therefore, the range of θ is defined as (-π, π).

[0080] The material selection and machining precision of the scroll compressor have an important influence on the performance of the scroll compressor. In actual application, the performance of the scroll compressor needs to be verified through experiments, and the experimental results are used for optimization design to improve the operation efficiency and stability of the scroll compressor.

[0081] Embodiment 2:

[0082] This embodiment provides a CO2 scroll compressor intermediate exhaust hole as shown in Figure 2 The first intermediate exhaust hole and the second intermediate exhaust hole are also symmetrically distributed relative to the base circle of the static scroll, that is, the centers of the two intermediate exhaust holes are parallel to the tangent B'C' and D'F' of the base circle.

[0083] At the moment shown in Figure 2 , the dynamic scroll and the static scroll are at the moment before the beginning of the engagement, that is, the two symmetric working cavities will merge into the central cavity to become a new cavity. At this moment, the first intermediate exhaust hole and the inner profile line of the static scroll are tangent to point A', and the second intermediate exhaust hole and the outer profile line of the static scroll are tangent to point E', and A' point and E' point are also the engagement points of the dynamic scroll and the static scroll.

[0084] The variable wall thickness profile can be more flexible in design according to the working conditions and requirements of the scroll compressor, and the performance of the scroll compressor is optimized. In this embodiment, the design of the variable wall thickness profile enables the scroll to better adapt to the compression and expansion process of the gas during operation, reducing energy loss. According to the geometric characteristics of the variable diameter base circle involute, the design method of the CO2 scroll compressor intermediate exhaust hole is given as:

[0085] The angle between the center B' of the first intermediate exhaust hole and the tangent B'C' of the base circle of the static scroll and the x-axis of the static scroll is θ, and the counterclockwise direction is the positive direction of θ, and the value range of θ is (-π, π).

[0086] For the variable base circle radius involute, the base circle radius is:

[0087] a(φ)=a0+δ0φ k

[0088] where a0 represents the initial radius of the base circle, δ0 represents a parameter controlling the rate of change of the base circle radius with angle, φ represents the angle of development, and k represents a parameter for controlling the nonlinear influence of φ on the base circle radius.

[0089] The curvature radius of the outer side profile is:

[0090]

[0091] The equation of the outer side profile is:

[0092]

[0093] The spread angle of the inner side profile is in :

[0094] The spread angle of the inner side profile is in : in out

[0095] wherein, ai n represents the starting angle of the inner side involute, and a out represents the starting angle of the outer side involute.

[0096] The curvature radius of the inner side profile is:

[0097]

[0098] The equation of the inner side profile is:

[0099]

[0100] The first intermediate exhaust hole is tangent to the inner side involute of the static scroll at point A', the center B' of the circle is located on the generating line of the involute at point A', the radius of the circle is r1, the generating line is tangent to the base circle of the static scroll at point C', and the coordinates (x B' , y B' ) of the center of the first intermediate exhaust hole are:

[0101]

[0102] The second intermediate exhaust hole is tangent to the outer side involute of the static scroll at point E', the center F' of the circle is located on the generating line of the involute at point E', the radius of the circle is r2, and the generating line is tangent to the base circle of the static scroll at point D'. The coordinates (x F' , y F' ) of the center of the second intermediate exhaust hole are:

[0103]

[0104] ​For the variable wall thickness scroll compressor with symmetric arc correction and symmetric arc plus straight line correction, both have a connection arc correction angle γ, and only when θ < γ, the first intermediate exhaust hole and the second intermediate exhaust hole can still be connected with the symmetric working cavity for a period of time after the meshing of the dynamic scroll and the static scroll, thereby ensuring the uniformity of the symmetric working cavity pressure. Therefore, the design of the intermediate exhaust hole of the variable wall thickness scroll compressor with symmetric arc plus straight line correction also needs to follow the rule of θ < γ.

[0105] It should be noted that for the variable wall thickness scroll compressor with symmetric arc correction and symmetric arc plus straight line correction, the connection arc correction angle γ > 0, and the range of θ is still applicable. In practical applications, the performance of the scroll compressor needs to be verified through experiments, and the design is optimized according to the experimental results. For example, the value range of the included angle θ, the size of the connection arc correction angle and other parameters can be adjusted to further improve the operating efficiency and stability of the scroll compressor. The design of the variable wall thickness profile makes the scroll better adapt to the compression and expansion process of the gas during operation, reducing energy loss.

[0106] The above is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method of designing a CO2 scroll compressor intermediate exhaust port, characterized by, The design method is based on a CO2 scroll compressor intermediate exhaust hole, the CO2 scroll compressor intermediate exhaust hole includes a first intermediate exhaust hole and a second intermediate exhaust hole, the first intermediate exhaust hole and the second intermediate exhaust hole are symmetrically distributed about the center of the static scroll base circle, the center of the first intermediate exhaust hole is parallel to the tangent of the static scroll base circle and the center of the second intermediate exhaust hole is parallel to the tangent of the static scroll base circle; The CO2 scroll compressor intermediate exhaust hole design method includes: According to the position relationship between the static scroll base circle and the intermediate exhaust hole, the center and radius of the intermediate exhaust hole are determined; The center position of the intermediate exhaust hole is corrected, and the position and size of the intermediate exhaust hole are determined according to the corrected center and radius; The correction method includes symmetric arc correction and symmetric arc plus straight line correction, and the corrected scroll compressor has a connection arc correction angle, the angle between the center of the first intermediate exhaust hole and the tangent of the static scroll base circle and the static scroll x-axis is less than the connection arc correction angle.

2. The method of designing a CO2 scroll compressor intermediate exhaust port according to claim 1, wherein The angle between the tangent of the center of the first intermediate exhaust hole and the static vortex disc x-axis is in the range of .

3. The method of designing a CO2 scroll compressor intermediate discharge orifice according to claim 1, wherein The first intermediate exhaust hole is tangent to the inside involute of the static scroll, the center of the first intermediate exhaust hole is located on the generating line of the involute at the tangent point, and the generating line is tangent to the static scroll base circle.

4. The method of designing a CO2 scroll compressor intermediate discharge orifice according to claim 1, wherein The second intermediate exhaust hole is tangent to the outside involute of the static scroll, the center of the second intermediate exhaust hole is located on the generating line of the involute at the tangent point, and the generating line is tangent to the static scroll base circle.

5. The CO2 scroll compressor middle exhaust port design method of claim 1, wherein For a static scroll with a fixed base circle, the center coordinates of the first intermediate exhaust hole are: wherein, and respectively represent the horizontal and vertical coordinates of the center of the first intermediate exhaust hole, represents the base circle radius, represents the involute start angle, represents the angle between the tangent of the center of the first intermediate exhaust hole and the x-axis of the static scroll, represents the radius of the first intermediate exhaust hole; The center coordinates of the second intermediate exhaust hole are: wherein, and respectively represent the x and y coordinates of the center of the second intermediate exhaust hole, represents the radius of the second intermediate exhaust hole.

6. The CO2 scroll compressor middle exhaust port design method of claim 1, wherein For a static scroll with a variable base circle, the center determination method of the intermediate exhaust hole is: According to the involute of the variable base circle radius, the base circle radius is determined, the curvature radius of the outside profile is obtained, and the outside profile equation is constructed; According to the inside profile spread angle, the curvature radius of the inside profile is determined, and the inside profile equation is constructed; Based on the outside profile equation and the inside profile equation, the center coordinates of the first intermediate exhaust hole and the second intermediate exhaust hole are determined.

7. The CO2 scroll compressor middle exhaust port design method of claim 6, wherein The base circle radius is wherein, denotes the base circle initial radius, denotes a parameter controlling the rate of change of the base circle radius with angle, denotes the angle of development, denotes a parameter for controlling a non-linear influence on the base circle radius; The curvature radius of the outside profile is ； Then the outside profile equation is: ； The inside profile spread angle is wherein denotes the inside involute start angle, denotes the outside involute start angle; The curvature radius of the inside profile is Then the inside profile equation is: 。 8. The CO2 scroll compressor middle exhaust port design method of claim 6, wherein, The center coordinates of the first intermediate exhaust hole are: ； The center coordinates of the second intermediate exhaust hole are: 。

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