A scroll compressor having a middle shell with a barrel-shaped section

Abstract

The scroll compressor (2) includes a compressor casing (3) including an upper shell (6), a middle shell (7) and a bottom shell (8); a compression unit (11) mounted inside the compressor casing (3); a drive shaft (14) disposed inside the compressor casing (3); an electric motor (15) disposed inside the compressor casing (3) in the middle shell (7) and configured to rotatably drive the drive shaft (14); an oil sump (9) disposed inside the compressor casing (3) in the bottom shell (8); and a baseplate (16) fixed to the bottom shell (8). The middle shell (7) includes at least one barrel shaped section (B) extending in an axial direction (Z), the at least one barrel-shaped section (B) having a longitudinal profile which is arcuate and which has a radius of curvature.

Description

[0001] DESCRIPTION

[0002] TITLE : A scroll compressor having a middle shell with a barrel-shaped section

[0003] Field of the invention

[0004] The invention relates to a scroll compressor.

[0005] Background art

[0006] Scroll compressors are very widely used for refrigerant applications. However, the application range is limited, especially because of a high level of noise produced during the operation of a scroll compressor. The acoustic sound level of a scroll compressor is usually between 80 dB(A) and 90 dB(A) and even higher, which is a significant issue for applications in a proximity of human activities.

[0007] Typically, a scroll compressor comprises a compressor casing including a bottom shell delimiting an oil sump, a middle shell provided with a suction volume and housing an electric motor, and an upper shell provided with a compression volume and a discharge volume.

[0008] The main sources of noise in a scroll compressor are the compression of the refrigerant at the compression volume, the mechanical contact between the fixed scroll and the orbiting scroll and the discharge of a compressed refrigerant in the discharge volume. There are also noise sources which are less significant in relation to the sources from the upper shell. As an example, such source of the noise may be the electric motor.

[0009] In recent years, many efforts have been made in order to reduce the overall noise of a scroll compressor.

[0010] One way of providing a noise reduction of a scroll compressor is to provide a noise-reduction cover for the entire scroll compressor. An example of such solutions is disclosed in US2005274569A1 . However, such solutions reduce the noise generated by a scroll compressor in a passive way. In other words, a scroll compressor still generates noise (and therefore e.g. vibrations, which affect the lifetime of a compressor), but the noise experienced by an user is reduced. Moreover, such solutions affect the cooling of a scroll compressor and therefore a scroll compressor is exposed for overheating.

[0011] Other type of technical solution for providing a noise reduction of a scroll compressor relates to including additional muffling devices inside the scroll compressor in the upper shell. As an example of such solution, FR3129693A1 discloses a discharge muffler which is located in the discharge volume and mounted at a discharge passage from the compression volume. However, such solutions may affect the flow of the refrigerant through a scroll compressor and therefore may affect the efficiency of a scroll compressor. It is known in prior art for reciprocating compressors, which are not a part of the present invention, to design an external housing of a hermetic compressor which is capable of reducing noises and vibrations. Exemplary solutions are disclosed in US4384635A and US5281105A. However, these solutions developed for reciprocating compressors cannot be easily introduced into scroll compressors, which e.g. have different internal arrangements of the electric motor and the compression assembly, different type of a motion of the compression assembly, different structure of the compressor casing and different arrangement of the suction volume and the discharge volume. Moreover, solutions known from reciprocating compressors are aimed in reducing the overall noise of an entire reciprocating compressor and not only a selected part of the reciprocating compressor. It should be noted that some parts of a scroll compressor have a limited design freedom due to their function, e.g. the bottom shell with the oil sump. The bottom shell should be also adapted to provide a safe support together with a baseplate of a scroll compressor.

[0012] Therefore, the prior art is silent about solutions for reducing the noise of a scroll compressor coming from a middle shell. Moreover, since a middle shell is usually manufactured by rolling a tube and welding it, a designing freedom is limited.

[0013] It is an object of the present invention to overcome the above-mentioned drawbacks from the prior art solutions and to provide a scroll compressor with an improved noise reduction. Especially, it is an object of the present invention to provide a scroll compressor with an improved middle shell in terms of noise reduction properties for the noise coming from the middle shell of the scroll compressor.

[0014] Summary of the invention

[0015] According to the present invention, there is provided a scroll compressor including:

[0016] - a compressor casing provided with a suction fitting configured to supply the scroll compressor with refrigerant gas to be compressed and a discharge fitting configured to discharge compressed refrigerant gas, wherein the compressor casing includes an upper shell, a middle shell and a bottom shell,

[0017] - a compression unit mounted inside the compressor casing and configured to compress the refrigerant gas supplied by the suction fitting, wherein the compression unit includes a fixed scroll and an orbiting scroll configured to perform an orbiting movement relative to the fixed scroll during operation of the scroll compressor,

[0018] - a drive shaft disposed inside the compressor casing and coupled with the orbiting scroll,

[0019] - an electric motor disposed inside the compressor casing in the middle shell and configured to rotatably drive the drive shaft,

[0020] - an oil sump disposed inside the compressor casing and at least partially delimited by the bottom shell, and

[0021] - a baseplate fixed to the bottom shell, characterized in that the middle shell includes at least one barrel-shaped section extending in an axial direction, the at least one barrel-shaped section having a longitudinal profile which is arcuate and which has a radius of curvature.

[0022] Such a configuration of the middle shell, and particularly the presence of the at least one barrelshaped section, reduces important acoustic parameters like nodal mode number, equivalent radiated power level, far field sound power level, radiated factor and harmonic response. As a result, the noise level generated by the scroll compressor according to the present invention is substantially reduced.

[0023] Moreover, thanks to the at least one barrel-shaped section, the stiffness of the middle shell is improved, which also improves the noise properties of the scroll compressor according to the present invention.

[0024] By reducing the acoustic response of the scroll compressor according to the present invention, overall vibrations of the scroll compressor are also reduced. Thus, a risk of crack formation for all the piping connected to the compressor casing is reduced. Further, a lifetime of the scroll compressor may be increased.

[0025] Advantageously, with the scroll compressor with the middle shell according to the present invention, it is possible to obtain an increase of first modal frequencies compared to a standard cylindrical middle shell up to 70% on first ones and reduce the overall noise by about 3dB depending on the radius of curvature and end diameter, also named head diameter, of the barrelshaped section.

[0026] The scroll compressor may also include one or more of the following features, taken alone or in combination.

[0027] According to an embodiment of the invention, the radius of curvature of the at least one barrelshaped section is substantially constant in the axial direction.

[0028] According to an embodiment of the invention, the radius of curvature of the at least one barrelshaped section is from 0,5 m to 1 ,5 m.

[0029] According to an embodiment of the invention, the at least one barrel-shaped section includes a first end having a first end diameter and a second end having a second end diameter.

[0030] According to an embodiment of the invention, the second end diameter is unequal to the first end diameter.

[0031] According to an embodiment of the invention, the longitudinal profile of the at least one barrelshaped section extends from the first end of the at least one barrel-shaped section to the second end of the at least one barrel-shaped section.

[0032] According to an embodiment of the invention, the at least one barrel-shaped section includes an intermediate portion having an intermediate diameter which is respectively greater than the first and second end diameters.

[0033] According to an embodiment of the invention, a ratio between the radius of curvature of the at least one barrel-shaped section and the first end diameter is from 1 .5 to 4.5.

[0034] According to an embodiment of the invention, the middle shell includes at least one end cylindrical section. Said at least one end cylindrical section facilitates the manufacturing of the middle shell according to the invention.

[0035] According to an embodiment of the invention, the middle shell includes a first end cylindrical section having a first cylindrical section diameter and a second end cylindrical section having a second cylindrical section diameter, the at least one barrel-shaped section being axially located between the first and second end cylindrical sections.

[0036] According to an embodiment of the invention, at least one of the first cylindrical section diameter and the second cylindrical section diameter is substantially identical to the first end diameter.

[0037] According to an embodiment of the invention, each of the first cylindrical section diameter and the second cylindrical section diameter is substantially identical to the first end diameter.

[0038] According to an embodiment of the invention, the first and second end cylindrical sections have substantially a same length measured in the axial direction.

[0039] According to an embodiment of the invention, the first and second end cylindrical sections have different lengths measured in the axial direction.

[0040] According to an embodiment of the invention, the middle shell includes at least a first barrelshaped section and a second barrel-shaped section each extending in the axial direction, the first barrel-shaped section having a first longitudinal profile which is arcuate and which has a first radius of curvature and the second barrel-shaped section having a second longitudinal profile which is arcuate and which has a second radius of curvature.

[0041] According to an embodiment of the invention, the first radius of curvature and the second radius of curvature are different from each other. By providing multiple barrel-shaped sections with different geometries, it is possible to reduce different frequencies of the generated noise.

[0042] According to another embodiment of the invention, the first radius of curvature and the second radius of curvature are substantially identical.

[0043] According to an embodiment of the invention, the first and second barrel-shaped sections have different lengths measured in the axial direction. By providing multiple barrel-shaped sections with different geometries, it is possible to reduce different frequencies of the generated noises. According to an embodiment of the invention, a ratio between the length of the first barrel-shaped section and the length of the second barrel-shaped section is from 0.2 to 0.8.

[0044] According to another embodiment of the invention, the first and second barrel-shaped sections have a same length measured in the axial direction.

[0045] According to an embodiment of the invention, the middle shell includes a first end cylindrical section, a second end cylindrical section and first and second barrel-shaped sections axially located between the first and second end cylindrical sections.

[0046] According to an embodiment of the invention, the middle shell has a regular circular crosssection.

[0047] According to an embodiment of the invention, the middle shell has a cross-section having at least one lobe. Additional corrugation in form of at least one lobe further increases the stiffness of the middle shell and therefore further improves the noise properties of the scroll compressor according to the present invention.

[0048] According to an embodiment of the invention, the middle shell has a circular cross-section having at least one lobe.

[0049] According to an embodiment of the invention, the middle shell has a cross-section having at least two lobes, wherein the lobes have the same lobe radiuses.

[0050] According to an embodiment of the invention, the middle shell has a cross-section having at least two lobes, wherein the lobes have different lobe radiuses.

[0051] According to an embodiment of the invention, the middle shell has a circular cross-section having three lobes. The lobes may have different lobe radiuses or the same lobe radiuses.

[0052] According to an embodiment of the invention, the middle shell includes an upper end closed by the upper shell and a lower end closed by the bottom shell.

[0053] Brief description of the drawings

[0054] The following detailed description of several embodiments of the invention is better understood when read in conjunction with the appended drawings being understood, however, that the invention is not limited to the specific embodiments disclosed.

[0055] Figure 1 is a longitudinal section view of a scroll compressor according to a first embodiment of the invention.

[0056] Figure 2 is a partial schematic longitudinal section view of a middle shell of the scroll compressor of figure 1 .

[0057] Figure 3 is a cross section view of the middle shell of figure 2.

[0058] Figure 4 is a schematic longitudinal section view of a middle shell of a scroll compressor according to a second embodiment of the invention.

[0059] Figure 5 is a schematic longitudinal section view of a middle shell of a scroll compressor according to a third embodiment of the invention.

[0060] Figure 6 is a cross section view of a middle shell of a scroll compressor according to a fourth embodiment of the invention.

[0061] Figure 7 is a cross section view of a middle shell of a scroll compressor according to a fifth embodiment of the invention.

[0062] Detailed description of the preferred embodiments

[0063] Embodiment 1 : middle shell with a barrel-shaped section

[0064] A first embodiment of a scroll compressor 2 according to the present invention is shown in figures 1 to 3.

[0065] The scroll compressor 2 comprises a compressor casing 3 provided with a suction fitting 4 configured to supply the scroll compressor 2 with refrigerant gas to be compressed and a discharge fitting 5 configured to discharge compressed refrigerant gas.

[0066] The compressor casing 3 includes an upper shell 6, also named upper cap, a middle shell 7 and a bottom shell 8. Particularly, the middle shell 7 includes an upper end closed by the upper shell 6 and a lower end closed by the bottom shell 8. For example, the suction fitting 4 may be provided on the middle shell 7 and the discharge fitting 5 may be provided on the upper shell 6.

[0067] The scroll compressor 2 also includes an oil sump 9 arranged inside the compressor casing 3 and delimited by the bottom shell 8. The oil sump 9 is configured to store oil.

[0068] Furthermore, the scroll compressor 2 comprises a support frame 10 arranged within the compressor casing 3 and secured to the compressor casing 3, and a compression unit 11 also arranged within the compressor casing 3 and disposed above the support frame 10. The compression unit 11 is configured to compress the refrigerant gas supplied by the suction fitting 4, and includes a fixed scroll 12, which is fixed in relation to the compressor casing 3, and an orbiting scroll 13 supported by and in slidable contact with a thrust bearing surface provided on the support frame 10. The orbiting scroll 13 is configured to perform an orbiting movement relative to the fixed scroll 12 during operation of the scroll compressor 2.

[0069] The scroll compressor 2 further includes a drive shaft 14 disposed inside the compressor casing 3 and configured to drive the orbiting scroll 13 in an orbital movement, and an electric motor 15 disposed inside the compressor casing 3 and coupled to the drive shaft 14. The electric motor 15 is particularly configured to drive in rotation the drive shaft 14 about a rotational axis A. According to the first embodiment shown on figures 1 to 3, the electric motor 15 is disposed below the support frame 10 and is arranged in the middle shell 7. In addition, the scroll compressor 2 includes a baseplate 16 fixed to the bottom shell 8, and configured to provide a stable support for the scroll compressor 2. The baseplate 16 may for example be mounted on two mounting rails extending substantially parallel to each other.

[0070] As better shown on figure 2, the middle shell 7 includes a barrel-shaped section B extending in an axial direction Z. The barrel-shaped section B includes a first end having a first end diameter D1 and a second end having a second end diameter D2 which is identical to the first end diameter D1. The first end diameter D1 and the second end diameter D2 are also known as the end diameter or head diameter of a barrel. Particularly, the barrel-shaped section B includes an intermediate portion having an intermediate diameter which is respectively greater than the first and second end diameters D1 , D2.

[0071] The barrel-shaped section B has a longitudinal profile which is arcuate and which has a radius of curvature R. Advantageously, the radius of curvature R of the barrel-shaped section B is constant in the axial direction Z and from the first end of the barrel-shaped section B to the second end of the barrel-shaped section B. The radius of curvature R of the barrel-shaped section B may be for example from 0,5 m to 1 ,5 m. A ratio between the radius of curvature R of the barrelshaped section B and the first end diameter D1 may by from 1 .5 to 4.5.

[0072] According to the first embodiment of the invention, the middle shell 7 has a regular circular crosssection, as shown in figure 3, and further includes an end cylindrical section C secured to the upper shell 6 and an intermediate section E axially located between the barrel-shaped section B and the end cylindrical section C.

[0073] Embodiment 2: middle shell with a barrel-shaped section and two end cylindrical sections

[0074] Figure 4 shows a scroll compressor 2 according to a second embodiment of the present invention which differs from the first embodiment essentially in that the middle shell 7 includes a first end cylindrical section C1 having a first cylindrical section diameter and a second end cylindrical section C2 having a second cylindrical section diameter, and in that the barrel-shaped section B is axially located between the first and second end cylindrical sections C1 , C2.

[0075] According to the second embodiment of the invention, each of the first cylindrical section diameter and the second cylindrical section diameter is identical to the first end diameter D1 , and thus to the second end diameter D2. However, in other embodiments of the present invention, the first and second cylindrical section diameters may be different from each other, and may be different from the first end diameter D1 .

[0076] According to the second embodiment of the invention, the first end cylindrical section C1 and the second end cylindrical section C2 have different lengths measured in the axial direction Z. However, in other embodiments of the present invention, the first end cylindrical section C1 and the second end cylindrical section C2 may have substantially a same length measured in the axial direction Z. Embodiment 3: middle shell with two barrel-shaped sections and two end cylindrical sections

[0077] Figure 5 shows a scroll compressor 2 according to a third embodiment of the present invention which differs from the second embodiment essentially in that the middle shell 7 includes a first barrel-shaped section B1 and a second barrel-shaped section B2 axially located between the first and second end cylindrical sections C1 , C2 and each extending in the axial direction Z.

[0078] The first barrel-shaped section B1 has a first longitudinal profile which is arcuate and which has a first radius of curvature R1 and the second barrel-shaped section B2 has a second longitudinal profile which is arcuate and which has a second radius of curvature R2.

[0079] According to the third embodiment of the invention, the first radius of curvature R1 and the second radius of curvature R2 are different from each other. However, in other embodiments of the present invention, the first radius of curvature R1 may be equal to the second radius of curvature R2.

[0080] According to the third embodiment of the invention, the first and second barrel-shaped sections B1 , B2 have different lengths measured in the axial direction Z. A ratio between the length of the first barrel-shaped section B1 and the length of the second barrel-shaped section B2 may for example be from 0.2 to 0.8. However, in other embodiments of the present invention, the first barrel-shaped section B1 and the second barrel-shaped section B2 may have a same length measured in the axial direction Z.

[0081] In other embodiments of the present invention, the first and second barrel-shaped sections B1 , B2 and the first and second end cylindrical sections C1 , C2 may be disposed in any order, looking in the axial direction Z.

[0082] Embodiment 5: middle shell with a circular cross-section with identical lobes

[0083] Figure 6 shows a scroll compressor 2 according to a fourth embodiment of the present invention which differs from the first embodiment essentially in that the middle shell 7 has a circular crosssection having three identical lobes L, i.e. lobes having the same lobe radiuses. Such arrangement of identical lobes provides an additional increase in the stiffness of the middle shell 7 and therefore further improves the noise properties of the scroll compressor 2 according to the present invention. In particular, a basically uniform increase of the stiffness may be obtained with identical lobes.

[0084] According to the fourth embodiment of the invention, the lobes L are regularly angularly distributed around the rotational axis A.

[0085] Embodiment 6: middle shell with circular cross-section with different lobes

[0086] Figure 7 shows a scroll compressor 2 according to a fifth embodiment of the present invention which differs from the fourth embodiment essentially in that the middle shell 7 has a circular cross-section having three different lobes L1 , L2 and L3, i.e. lobes having different lobe radiuses. Such arrangement of lobes provides different levels of stiffness in different sections of the middle shell 7. By doing this, it is possible to increase the stiffness of the middle shell 7 in a particular section / region, e.g. in area where an additional equipment is mounted on the middle shell 7. Features described in relation to a particular embodiment of the present invention may obviously be applied in other embodiments unless particularly specified otherwise.

[0087] Of course, the invention is not restricted to the embodiments described above by way of nonlimiting examples, but on the contrary it encompasses all embodiments thereof.

Claims

CLAIMS1 . A scroll compressor (2) including:- a compressor casing (3) provided with a suction fitting (4) configured to supply the scroll compressor (2) with refrigerant gas to be compressed and a discharge fitting (5) configured to discharge compressed refrigerant gas, wherein the compressor casing (3) includes an upper shell (6), a middle shell (7) and a bottom shell (8),- a compression unit (1 1) mounted inside the compressor casing (3) and configured to compress the refrigerant gas supplied by the suction fitting (4), wherein the compression unit (11) includes a fixed scroll (12) and an orbiting scroll (13) configured to perform an orbiting movement relative to the fixed scroll (12) during operation of the scroll compressor (2),- a drive shaft (14) disposed inside the compressor casing (3) and coupled with the orbiting scroll (13),- an electric motor (15) disposed inside the compressor casing (3) in the middle shell (7) and configured to rotatably drive the drive shaft (14),- an oil sump (9) disposed inside the compressor casing (3) and at least partially delimited by the bottom shell (8), and- a baseplate (16) fixed to the bottom shell (8), characterized in that the middle shell (7) includes at least one barrel-shaped section (B) extending in an axial direction (Z), the at least one barrel-shaped section (B) having a longitudinal profile which is arcuate and which has a radius of curvature (R).

2. The scroll compressor (2) according to claim 1 , wherein the radius of curvature (R) of the at least one barrel-shaped section (B) is from 0,5 m to 1 ,5 m.

3. The scroll compressor (2) according to claim 1 or 2, wherein the at least one barrel-shaped section (B) includes a first end having a first end diameter (D1) and a second end having a second end diameter (D2).

4. The scroll compressor (2) according to claim 3, wherein the second end diameter (D2) is substantially identical to the first end diameter (D1).

5. The scroll compressor (2) according to claim 3, wherein the second end diameter (D2) is unequal to the first end diameter (D1).

6. The scroll compressor (2) according to any one of claims 3 to 5, wherein a ratio between the radius of curvature (R) of the at least one barrel-shaped section (B) and the first end diameter (D1) is from 1 .5 to 4.5.

7. The scroll compressor (2) according to any one of claim 1 to 6, wherein the middle shell (7) includes at least one end cylindrical section (C).

8. The scroll compressor (2) according to any one of claim 1 to 7, wherein the middle shell (7) includes a first end cylindrical section (C1) having a first cylindrical section diameter and a second end cylindrical section (C2) having a second cylindrical section diameter, the at least one barrel-shaped section (B) being axially located between the first and second end cylindrical sections (C1 , C2).

9. The scroll compressor (2) according to claim 8, wherein at least one of the first cylindrical section diameter and the second cylindrical section diameter is substantially identical to the first end diameter (D1).

10. The scroll compressor (2) according to claim 8 or 9, wherein the first and second end cylindrical sections (C1 , C2) have substantially a same length measured in the axial direction (Z).11 . The scroll compressor (2) according to claim 8 or 9, wherein the first and second end cylindrical sections (C1 , C2) have different lengths measured in the axial direction (Z).

12. The scroll compressor (2) according to any one of claims 1 to 11 , wherein the middle shell (7) includes at least a first barrel-shaped section (B1) and a second barrel-shaped section (B2) each extending in the axial direction (Z), the first barrel-shaped section (B1) having a first longitudinal profile which is arcuate and which has a first radius of curvature (R1) and the second barrel-shaped section (B2) having a second longitudinal profile which is arcuate and which has a second radius of curvature (R2).

13. The scroll compressor (2) according to claim 12, wherein the first radius of curvature (R1) and the second radius of curvature (R2) are different from each other.

14. The scroll compressor (2) according to claim 12 or 13, wherein the first and second barrel-shaped sections (B1 , B2) have different lengths measured in the axial direction (Z).

15. The scroll compressor (2) according to claim 14, wherein a ratio between the length of the first barrel-shaped section (B1) and the length of the second barrel-shaped section (B2) is from 0.2 to 0.8.

16. The scroll compressor (2) according to any one of claims 1 to 15, wherein the middle shell (7) has a regular circular cross-section.

17. The scroll compressor (2) according to any one of claims 1 to 15, wherein the middle shell (7) has a cross-section having at least one lobe.

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