SEALING STRUCTURE AND SCROLL AIR COMPRESSOR HAVING SAME

Abstract

Disclosed are a sealing structure and a scroll air compressor having the same. The sealing structure includes: an orbiting scroll including an orbiting scroll spiral tooth (11), the orbiting scroll spiral tooth (11) being provided with an orbiting scroll spiral tooth groove (12), an orbiting scroll wear-resistant sealing strip (30) being provided in the orbiting scroll spiral tooth groove (12); a stationary scroll including a stationary scroll spiral tooth (21) matched with the orbiting scroll spiral tooth (11), the stationary scroll spiral tooth (21) being provided with a stationary scroll spiral tooth groove (22), a stationary scroll wear-resistant sealing strip (40) is provided in the stationary scroll spiral tooth groove (22), the wear-resistant sealing strip (30) is divided into sections including a high-temperature and high-pressure section (30a) and a medium-temperature and medium-pressure section (30b). The sealing structure reduces costs of use and maintenance of the sealing strip; a buffer contact surface of the wear-resistant sealing strip (30) in contact with a scroll surface is flat, which improves performances of sealing and noise-reduction; a bottom surface of the wear-resistant sealing strip (30) is equipped with a sealing ring having a cross section in a shape of a circle or a circular tube, which improves the damping and buffering performances; thereby the performance of the air compressor is improved, and the use cost of the air compressor is also reduced.

Claims

1. A sealing structure, comprising: an orbiting scroll comprising an orbiting scroll spiral tooth, wherein the orbiting scroll spiral tooth is provided with an orbiting scroll spiral tooth groove, an orbiting scroll wear-resistant sealing strip is provided in the orbiting scroll spiral tooth groove, the orbiting scroll wear-resistant sealing strip comprises the orbiting scroll wear-resistant sealing strip in a high-temperature and high-pressure section and the orbiting scroll wear-resistant sealing strip in a medium-temperature and medium-pressure section, a thickness of the orbiting scroll wear-resistant sealing strip is greater than a depth of the orbiting scroll spiral tooth groove; a stationary scroll comprising a stationary scroll spiral tooth matched with the orbiting scroll spiral tooth, wherein the stationary scroll spiral tooth is provided with a stationary scroll spiral tooth groove, a stationary scroll wear-resistant sealing strip is provided in the stationary scroll spiral tooth groove, the stationary scroll wear-resistant sealing strip comprises the stationary scroll wear-resistant sealing strip in the high-temperature and high-pressure section and the stationary scroll wear-resistant sealing strip in the medium-temperature and medium-pressure section, a thickness of the stationary scroll wear-resistant sealing strip is greater than a depth of the stationary scroll spiral tooth groove.

2. The sealing structure according to claim 1, wherein, the stationary scroll is provided with a damping sealing groove, an elastic damping component is provided in the damping sealing groove, and a damping wear-resistant sealing strip is provided on the orbiting scroll, the damping wear-resistant sealing strip abuts against the elastic damping component, an abutting portion of the damping wear-resistant sealing strip and the elastic damping component is lower than an upper end surface of the damping sealing groove; or, the orbiting scroll is provided with the damping sealing groove, the elastic damping component is provided in the damping sealing groove, the damping wear-resistant sealing strip is provided on the stationary scroll, the damping wear-resistant sealing strip abuts against the elastic damping component, the abutting portion is lower than the upper end surface of the damping sealing groove.

3. The sealing structure according to claim 1, wherein, the thickness of the orbiting scroll wear-resistant sealing strip in the high-temperature and high-pressure section is greater than the thickness of the orbiting scroll wear-resistant sealing strip in the medium-temperature and medium-pressure section, the orbiting scroll spiral tooth groove accordingly comprises the orbiting scroll spiral tooth groove in the high-temperature and high-pressure section and the orbiting scroll spiral tooth groove in the medium-temperature and medium-pressure section, the depth of the orbiting scroll spiral tooth groove in the high-temperature and high-pressure section is greater than the depth of the orbiting scroll spiral tooth groove in the medium-temperature and medium-pressure section; or, the thickness of the stationary scroll wear-resistant sealing strip in the high-temperature and high-pressure section is greater than the thickness of the stationary scroll wear-resistant sealing strip in the medium-temperature and medium-pressure section, the stationary scroll spiral tooth groove accordingly comprises the stationary scroll spiral tooth groove in the high-temperature and high-pressure section and the stationary scroll spiral tooth groove in the medium-temperature and medium-pressure section, the depth of the stationary scroll spiral tooth groove in the high-temperature and high-pressure section is greater than the depth of the stationary scroll spiral tooth groove in the medium-temperature and medium-pressure section.

4. The sealing structure according to claim 2, wherein cross sections of the orbiting scroll wear-resistant sealing strip, the stationary scroll wear-resistant sealing strip, and the damping wear-resistant sealing strip are in a shape of a square.

5. The sealing structure according to claim 2, wherein a cross section of the elastic damping component is in a shape of a circle or a circular tube, an outer diameter of the circle or the circular tube is between one half and three fifths of a depth of the damping sealing groove.

6. The sealing structure according to claim 2, wherein a thickness of the damping wear-resistant sealing strip is between one half and three fifths of the depth of the damping sealing groove.

7. The sealing structure according to claim 2, wherein a temperature resistance of the orbiting scroll wear-resistant sealing strip in the high-temperature and high-pressure section, a temperature resistance of the orbiting scroll wear-resistant sealing strip in the medium-temperature and medium-pressure section, and a temperature resistance of the damping wear-resistant sealing strip decrease in sequence.

8. The sealing structure according to claim 1, wherein a width of the orbiting scroll wear-resistant sealing strip is the same as that of the stationary scroll wear-resistant sealing strip.

9. The sealing structure according to claim 2, wherein surfaces of the orbiting scroll wear-resistant sealing strip, the stationary scroll wear-resistant sealing strip, and the damping wear-resistant sealing strip are smooth and flat.

10. The sealing structure according to claim 2, wherein, the orbiting scroll wear-resistant sealing strip in the high-temperature and high-pressure section and/or the stationary scroll wear-resistant sealing strip in the high-temperature and high-pressure section are made of a PTFE composite material comprising copper powder, molybdenum disulfide, carbon fiber or glass fiber, and a temperature resistance range thereof is −240° C. to 280° C.; the orbiting scroll wear-resistant sealing strip in the medium-temperature and medium-pressure section and/or the stationary scroll wear-resistant sealing strip in the medium-temperature and medium-pressure section are made of the PTFE composite material comprising LCP, molybdenum disulfide, carbon fiber or glass fiber, and a temperature resistance range thereof is −240° C. to 280° C.; the damping wear-resistant sealing strip is made of the PTFE composite material comprising PI, molybdenum disulfide, carbon fiber or glass fiber, and the temperature resistance range of the damping wear-resistant sealing strip is −220° C. to −250° C.; a material of the elastic damping component is any one of silica gel, latex, or polyethylene, or any one of composite materials with silica gel, latex, or polyethylene as a matrix.

11. The sealing structure according to claim 2, wherein a heat dissipation groove is provided on the stationary scroll, the damping sealing groove is provided between the stationary scroll spiral tooth and the heat dissipation groove; or, the heat dissipation groove is provided on the orbiting scroll, and the damping sealing groove is provided between the orbiting scroll spiral tooth and the heat dissipation groove.

12. The sealing structure according to claim 2, wherein elasticity and plasticity of the elastic damping component is better than that of the damping wear-resistant sealing strip.

13. The sealing structure according to claim 1, wherein, a base material of one of the orbiting scroll and the stationary scroll is a cast aluminum alloy or a forged aluminum alloy, and a base material of the other is powder metallurgy or a cast iron; or, the base materials of the orbiting scroll and the stationary scroll are both the cast aluminum alloy or the forged aluminum alloy, and one or both of the base materials of the orbiting scroll and the stationary scroll are treated with hard anodic oxidation or micro-arc oxidation.

14. A scroll air compressor, comprising the sealing structure according to claim 1.

15. The sealing structure according to claim 5, wherein the outer diameter of the circle or circular tube is smaller than the width of the damping groove.

16. The sealing structure according to claim 15, wherein a thickness of a wall of the tube with a cross section in the shape of the circular tube is less than one half of the outer diameter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG. 1 is a schematic structure diagram of a sealing structure according to the present disclosure.

[0042] FIG. 2 is a schematic structure diagram of an orbiting scroll.

[0043] FIG. 3 is a schematic structure diagram of a stationary scroll.

[0044] FIG. 4 is a schematic structure diagram of a wear-resistant sealing strip in a high-temperature and high-pressure section of an orbiting scroll.

[0045] FIG. 5 is schematic a structure diagram of a wear-resistant sealing strip in a medium-temperature and medium-pressure section of an orbiting scroll.

[0046] FIG. 6 is a part composition diagram of wear-resistant sealing strips in a high-temperature and high-pressure section and in a medium-temperature and medium-pressure section, and an orbiting scroll.

[0047] FIG. 7 is a structure diagram of a wear-resistant sealing strip in a high-temperature and high-pressure section of a stationary scroll.

[0048] FIG. 8 is a structure diagram of a wear-resistant sealing strip in a medium-temperature and medium-pressure section of a stationary scroll.

[0049] FIG. 9 is a structure diagram of a damping and wear-resistant sealing strip in a damping sealing device.

[0050] FIG. 10 is a structure diagram of a damping elastic component in a damping sealing device.

[0051] FIG. 11 is a part composition diagram of a wear-resistant sealing strip in a high-temperature and high-pressure section, a wear-resistant sealing strip in a medium-temperature and medium-pressure section, a damping and wear-resistant sealing strip, a damping elastic component and a stationary scroll.

[0052] FIG. 12 is a partial cross-sectional view showing matching of a wear-resistant sealing strip and a scroll;

[0053] FIG. 13 is a partial cross-sectional view showing matching of a damping sealing device (which is circular) and a scroll.

[0054] FIG. 14 is a partial cross-sectional view showing matching of a damping sealing device (which is circular) and a scroll.

[0055] Reference signs: 10, orbiting scroll; 11, orbiting scroll spiral tooth; 12, orbiting scroll spiral tooth groove; 12a, orbiting scroll spiral tooth groove in a high-temperature and high-pressure section; 12b, orbiting scroll spiral tooth groove in a medium-temperature and medium-pressure section; 20, stationary scroll; 21, stationary scroll spiral tooth; 22, stationary scroll spiral tooth groove; 22a, stationary scroll spiral tooth groove in a high-temperature and high-pressure section; 22b, stationary scroll spiral tooth groove in a medium-temperature and medium-pressure section; 23, damping sealing groove; 24, heat dissipation groove; 30, orbiting scroll wear-resistant sealing strip; 30a, orbiting scroll wear-resistant sealing strip in a high-temperature and high-pressure section; 30b, orbiting scroll wear-resistant sealing strip in a medium-temperature and medium-pressure section; 40, stationary scroll wear-resistant sealing strip; 40a, stationary scroll wear-resistant sealing strip in a high-temperature and high-pressure section; 40b, stationary scroll wear-resistant sealing strip in a medium-temperature and medium-pressure section; 50, damping wear-resistant sealing strip; 60, elastic damping component.

DETAILED DESCRIPTION

[0056] The present disclosure will be further described in detail below in conjunction with the accompanying drawings.

[0057] As for the problems of high cost and short life due to the use of an entire sealing strip, and lower sealing and noise reduction effects due to the use of a sealing device with a circular cross section in the related art, the present disclosure provides a sealing structure.

[0058] The sealing structure includes: an orbiting scroll and a stationary scroll. The orbiting scroll includes an orbiting scroll spiral tooth; the orbiting scroll spiral tooth is provided with an orbiting scroll spiral tooth groove; and in the orbiting scroll spiral tooth groove is provided an orbiting scroll wear-resistant sealing strip which includes an orbiting scroll wear-resistant sealing strip in a high-temperature and high-pressure section and an orbiting scroll wear-resistant sealing strip in a medium-temperature and medium-pressure section. A thickness of the orbiting scroll wear-resistant sealing strip is greater than a depth of the orbiting scroll spiral tooth groove. The stationary scroll includes a stationary scroll spiral tooth matched with the orbiting scroll spiral tooth; the stationary scroll spiral tooth is provided with a stationary scroll spiral tooth groove; and in the stationary scroll spiral tooth groove is provided a stationary scroll wear-resistant sealing strip. The stationary scroll wear-resistant sealing strip includes a stationary scroll wear-resistant sealing strip in a high-temperature and high-pressure section and a stationary scroll wear-resistant sealing strip in a medium-temperature and medium-pressure section. The thickness of the stationary scroll wear-resistant sealing strip is greater than the depth of the stationary scroll spiral tooth groove.

[0059] The stationary scroll is provided with a damping sealing groove; an elastic damping component is provided in the damping sealing groove; and a damping wear-resistant sealing strip is provided on the orbiting scroll. The damping wear-resistant sealing strip abuts against the elastic damping component, and an abutting portion is lower than an upper end surface of the damping sealing groove; or, a damping sealing groove is provided on the orbiting scroll, and in the damping sealing groove is provided an elastic damping component; the stationary scroll is provided with a damping wear-resistant sealing strip; the damping wear-resistant sealing strip abuts against the elastic damping component, and the abutting portion is lower than the upper end surface of the damping sealing groove.

[0060] In some embodiments, the sealing structure of the present disclosure is applied to a scroll air compressor.

[0061] The present disclosure reduces the costs of the use and maintenance of the sealing strip material. The buffer contact surface of the wear-resistant sealing strip in contact with the surface of the scroll is flat, which improves the performance of sealing and noise reduction. The bottom surface of the wear-resistant sealing strip is fitted with a sealing ring having a cross section in a shape of a circle or a circular tube, which improves the damping and buffering performances. In one embodiment, the performance of the air compressor compressing the air is improved, and the use cost of the air compressor is simultaneously greatly reduced.

[0062] In one embodiment, the sealing structure shown in FIG. 1 is taken as an example for detailed description.

[0063] An air compressor assembly in FIG. 1 includes an orbiting scroll 10 as shown in FIG. 2 and a stationary scroll 20 as shown in FIG. 3. The spiral teeth of the orbiting scroll and the stationary scroll are divided into a high-temperature and high-pressure section and a medium-temperature and medium-pressure section. The stationary scroll 20 is provided with a stationary scroll spiral tooth 21; and a top portion of the stationary scroll 21 is provided with a stationary scroll spiral tooth groove 22, in order to be able to embed the stationary scroll wear-resistant sealing strip 40; the orbiting scroll 10 is provided with an orbiting scroll spiral tooth 11 matched with the stationary scroll spiral tooth 21 on the stationary scroll 20; the top portion of the orbiting scroll spiral tooth 11 is provided with an orbiting scroll spiral tooth groove 12, in order to be able to embed the orbiting scroll wear-resistant sealing strip 30. In some embodiments, a width of the orbiting scroll wear-resistant sealing strip in the high-temperature and high-pressure section and the medium-temperature and medium-pressure section is the same as the width of the stationary scroll wear-resistant sealing strip in the high-temperature and high-pressure section and the medium-temperature and medium-pressure section; and the width is slightly smaller than the width of the spiral tooth groove. The thickness of the wear-resistant sealing strip in the high-temperature and high-pressure section is greater than the thickness of the wear-resistant sealing strip in the medium-temperature and medium-pressure section; and the thickness of the wear-resistant sealing strip in the high-temperature and high-pressure section and the medium-temperature and medium-pressure section is slightly higher than the depth of the spiral tooth groove. The width of the damping wear-resistant sealing strip in the damping sealing device is slightly smaller than the width of the damping groove; and the thickness of the damping wear-resistant sealing strip is between one half and three fifths of the depth of the damping groove.

[0064] During operation, the orbiting scroll 10 is snap-fitted with the stationary scroll 20; the orbiting scroll spiral tooth 11 is engaged with the stationary scroll spiral tooth 21, to move eccentrically by controlling the orbiting scroll 10 to make the orbiting scroll spiral tooth 11 move along a side wall of the stationary scroll spiral tooth groove 22, and the formed crescent-shaped compression chambers compress the air step by step. When air is compressed, the tooth surfaces of the stationary scroll spiral tooth 21 and the orbiting scroll spiral tooth 11 are no longer worn due to friction, and replaced by the friction loss of the wear-resistant sealing strips (including the orbiting scroll wear-resistant sealing strip 30 and the stationary scroll wear-resistant sealing strip 40). Moreover, the cost of replacing the wear-resistant sealing strip is lower, and the replacement is convenient, which greatly reduces the use cost of the air compressor and improves the reliability, performance and service life of the air compressor.

[0065] Referring to FIGS. 4-6, the orbiting scroll wear-resistant sealing strip 30 includes an orbiting scroll wear-resistant sealing strip 30a in a high-temperature and high-pressure section and an orbiting scroll wear-resistant sealing strip 30b in a medium-temperature and medium-pressure section; the orbiting scroll wear-resistant sealing strip 30a in a high-temperature and high-pressure section is embedded in an orbiting scroll spiral tooth groove 12a in the high-temperature and high-pressure section; the orbiting scroll wear-resistant sealing strip 30b in the medium-temperature and medium-pressure section is embedded in the orbiting scroll spiral tooth groove 12b in the medium-temperature and medium-pressure section. The structure of the stationary scroll wear-resistant sealing strip 40 is similar to that of the orbiting scroll wear-resistant sealing strip 30, with opposite rotation directions. The stationary scroll wear-resistant sealing strip 40 includes a stationary scroll wear-resistant sealing strip 40a in a high-temperature and high-pressure section as shown in FIG. 7 and a stationary scroll wear-resistant sealing strip 40b in a medium-temperature and medium-pressure section as shown in FIG. 8. In some embodiments, the wear-resistant sealing strip in the high-temperature and high-pressure section is PTFE with an added filler such as copper powder, molybdenum disulfide and carbon fiber or glass fiber, etc., and a temperature resistance range thereof is −240° C. to 280° C. The wear-resistant sealing strip in the medium-temperature and medium-pressure section is PTFE with an added filler such as liquid crystal polymer (LCP), molybdenum disulfide, carbon fiber or glass fiber, etc., and the temperature resistance range thereof is −240° C. to 280° C. The wear-resistant sealing strip in the damping section is PTFE with an added filler such as polyimide (PI), molybdenum disulfide, carbon fiber or glass fiber, etc., and the temperature resistance range thereof is −220° C. to 250° C. The temperature resistance and wear resistance of the wear-resistant sealing strip in the high-temperature and high-pressure section, the medium-temperature and medium-pressure section and the damping section are provided as that: wear-resistant sealing strip in the high-temperature and high-pressure section wear-resistant sealing strip in the medium-temperature and medium-pressure section wear-resistant sealing strip in the damping sealing device.

[0066] The widths of the spiral tooth grooves (including the orbiting scroll spiral tooth groove 12 and the stationary scroll spiral tooth groove 22) in the high-temperature and high-pressure section (including the orbiting scroll spiral tooth groove 12a in the high-temperature and high-pressure section and stationary scroll spiral tooth groove 22a in the high-temperature and high-pressure section) and the medium-temperature and medium-pressure section (including the orbiting scroll spiral tooth groove 12b in the medium-temperature and medium-pressure section and stationary scroll spiral tooth groove 22b in the medium-temperature and medium-pressure section) are both 2.4 mm. The groove depth of the spiral tooth groove in the high-temperature and high-pressure section is 3.4 mm, and the groove depth of the spiral tooth groove in medium-temperature and medium-pressure section is 2.4 mm.

[0067] Referring to FIG. 11, the stationary scroll wear-resistant sealing strip 40a in the high-temperature and high-pressure section is embedded in the stationary scroll spiral tooth groove 22a in the high-temperature and high-pressure section; and stationary scroll wear-resistant sealing strip 40b in the medium-temperature and medium-pressure section is embedded in the stationary scroll spiral tooth groove 22b in the medium-temperature and medium-pressure section.

[0068] A partial cross-section structure showing matching of the wear-resistant sealing strip and the scroll is shown in FIG. 12.

[0069] In one embodiment, the widths of wear-resistant sealing strips (including the orbiting scroll wear-resistant sealing strip 30 and the stationary scroll wear-resistant sealing strip 40) in the high-temperature and high-pressure section (including the orbiting scroll wear-resistant sealing strip 30a in the high-temperature and high-pressure section and the orbiting scroll wear-resistant sealing strip 40a in the medium-temperature and medium-pressure section) and the medium-temperature and medium-pressure section (including the orbiting scroll wear-resistant sealing strip 30b in the high-temperature and high-pressure section and the orbiting scroll wear-resistant sealing strip 40b in the medium-temperature and medium-pressure section) are both 2.25 mm. The thickness of the wear-resistant sealing strip in the high-temperature and high-pressure section is 3.5 mm, and the thickness of the wear-resistant sealing strip in the medium-temperature and medium-pressure section is 2.5 mm.

[0070] The surface of the wear-resistant sealing strip (including the orbiting scroll wear-resistant sealing strip 30 and the stationary scroll wear-resistant sealing strip 40) is smooth and flat. In some embodiments, the wear-resistant sealing strips in the high-temperature and high-pressure section (including the orbiting scroll wear-resistant sealing strip 30a in the high-temperature and high-pressure section and the orbiting scroll wear-resistant sealing strip 40a in the medium-temperature and medium-pressure section) are a PTFE (polytetrafluoroethylene) composite material with an added filler such as copper powder, molybdenum disulfide and carbon fiber or glass fiber, etc. The wear-resistant sealing strip in the medium-temperature and medium-pressure section (including the orbiting scroll wear-resistant sealing strip 30a in the high-temperature and high-pressure section and the orbiting scroll wear-resistant sealing strip 40a in the medium-temperature and medium-pressure section) is the PTFE composite material with an added filler such as liquid crystal polymer (LCP), molybdenum disulfide, carbon fiber or glass fiber, etc. In one embodiment, the temperature resistance range corresponding to the high-temperature and high-pressure section is −260° C. to 315° C., and the temperature resistance range corresponding to the medium-temperature and medium-pressure section is −240° C. to 280° C. the PTFE composite material has good performances such as wear resistance, self-lubrication, temperature resistance, corrosion resistance and impact resistance, etc.

[0071] Referring to FIG. 11, the stationary scroll 20 is provided with a damping sealing device, and the damping sealing device is located between the stationary scroll spiral tooth 21 of the stationary scroll 20 and the heat dissipation groove 24, and a cross section thereof is shown in FIG. 13 or FIG. 14. The elastic damping component 60 (shown in FIG. 10) is first embedded in the damping sealing groove 23 of the stationary scroll 20, and then the damping wear-resistant sealing strip 50 (shown in FIG. 9) is embedded in In the damping sealing groove 23 of the stationary scroll 20, the bottom surface of the damping wear-resistant sealing strip 50 is in close contact with the arc surface of the elastic damping component 60; and the front surface of the damping wear-resistant sealing strip 50 is closely fitted to the bottom surface of the spiral tooth of the orbiting scroll 10 by means of the rebound action of the elastic damping component 60. It should be appreciated that the elastic damping component 60 of the damping sealing device described above can also be provided in the orbiting scroll 10, and the damping wear-resistant sealing strip 50 is accordingly provided on the stationary scroll 20.

[0072] In some embodiments, the width of the damping sealing groove 23 is equal to 3 mm and the depth is equal to 2.8 mm; the width of the damping wear-resistant sealing strip 50 is equal to 2.9 mm and the thickness is equal to 2.8 mm; the surface of the damping wear-resistant sealing strip 50 is smooth and flat. In some embodiments, the damping wear-resistant sealing strip 50 is a PTFE composite material added with a filler such as polyimide (PI), molybdenum disulfide, carbon fiber or glass fiber, etc., and the heat range thereof is −220° C. to −250° C. The PTFE composite material has good properties such as wear resistance, self-lubrication, temperature resistance, corrosion resistance and impact resistance, etc. The material of the elastic damping component 60 is any one of silica gel, latex, or polyethylene, or any one of the composite materials with the silica gel, latex, or polyethylene as the matrix and other fillers, that is, the elastic damping component 60 is a composite material with a base material of silica gel or latex or polyethylene mixed with other fillers. The elasticity and plasticity of the elastic damping component 60 are better than those of the damping wear-resistant sealing strip 50.

[0073] Referring to FIGS. 10 and 11, the cross section of the elastic damping member 60 in the damping sealing device has two shapes: a circular shape and a circular tube shape. In some embodiments, the cross section of the embedded elastic damping component 60 is in the shape of a circle, and the diameter of the circle is equal to 2.8 mm; the cross section of the embedded elastic damping component 60 is in the shape of a circular tube, the outer diameter of the circular tube is equal to 2.8 mm, and the wall thickness of the tube is equal to 0.5 mm. The outer diameter of the circle or circular tube is between one half and three fifths of the depth of the damping groove, and meanwhile is smaller than the width of the damping groove. The thickness of the wall of the tube with a cross section in the shape of the circular tube is less than one half of the outer diameter.

[0074] The base material of one of the orbiting scroll and the stationary scroll is cast aluminum alloy or forged aluminum alloy, and the other is powder metallurgy or cast iron. Or the base materials of the movable scroll and the stationary scroll are both cast aluminum alloy or forged aluminum alloy, and one or two of them are treated with hard anodic oxidation or micro-arc oxidation.